01223nas a2200157 4500008004100000245009100041210006900132260000800201300001800209490000700227520064400234100002500878700002500903700001800928856011900946 2006 eng d00aSynthesis and utility of new amine/nucleobase addition products of allenylphosphonates0 aSynthesis and utility of new aminenucleobase addition products o cSEP a10152–101610 v623 a

In the reaction of allenylphosphonates with amines/nucleobases, depending on the amine and the allenylphosphonate, either Z- or E-vinylphosphonate or allylphosphonate as a single isomer with a β-amino functionality was isolated. A simple route to phosphonates with a β-NH2 group is developed by direct reaction with ammonia. In reactions with adenine, three different modes of reaction, with one of them involving an unusual cyclisation, are observed. The utility of (enamino)allyl phosphonate products thus obtained in the synthesis of (enamino)-1,3-butadienes via Horner–Wadsworth–Emmons (HWE) reaction is also demonstrated.

1 aSwamy, K., C. Kumara1 aBalaraman, Ekambaram1 aKumar, Satish uhttps://library.ncl.res.in/content/synthesis-and-utility-new-aminenucleobase-addition-products-allenylphosphonates01386nas a2200193 4500008004100000245013100041210006900172260000800241300001400249490000800263520066300271100002500934700002500959700001700984700002501001700001901026700001801045856012901063 2006 eng d00aUnusual products in the reactions of phosphorus(III) compounds with N=N, C equivalent to C or conjugated double-bonded systems0 aUnusual products in the reactions of phosphorusIII compounds wit cNOV a495–5010 v1183 a

The diversity of products in the reaction of diethyl azodicarboxylate (DEAD)/diisopropyl azodicarboxylate (DIAD) and activated acetylenes with PIII compounds bearing oxygen or nitrogen substituents is discussed. New findings that are useful in understanding the nature of intermediates involved in the Mitsunobu reaction are highlighted. X-ray structures of two new compounds (2-t-Bu-4-MeC6H3O)P (μ-N-t-Bu)2P+[(NH-t-Bu)N[(CO2]-i-Pr)(HNCO2-i-Pr)]](Cl-)(2-t-Bu-4-MeC6H3OH)(23)and [CH2(6-t-Bu-4-Me-C6H2O)2P(O)C(CO2Me)C-(CO2Me)CClNC(O)Cl] (33) are also reported. The structure of23 is close to one of the intermediates proposed in the Mitsunobu reaction.

1 aSwamy, K., C. Kumara1 aBalaraman, Ekambaram1 aPavan, Phani1 aKumar, N., N. Bhuvan1 aKumar, Praveen1 aKumar, Satish uhttps://library.ncl.res.in/content/unusual-products-reactions-phosphorusiii-compounds-nn-c-equivalent-c-or-conjugated-double02140nas a2200145 4500008004100000245020800041210006900249260000800318300001700326490000700343520144000350100002501790700002501815856015401840 2007 eng d00aConvenient chromatography-free access to enantio-pure 6,6’-di-tert-butyl-1,1’- binaphthalene-2,2’-diol- its 3,3’-dibromo, di-tert-butyl and phosphorus derivatives: utility in asymmetric synthesis0 aConvenient chromatographyfree access to enantiopure 66 ditertbut cSEP a 2037–20480 v183 a

A simple chromatography-free high-yielding synthesis of the hexane-soluble enantiopure 6,6′-di-tert-butyl-1,1′-binaphthalene-2,2′-diol 3 (6,6′-di-tert-butyl BINOL) using Friedel–Crafts reaction on 1,1′-binaphthalene-2,2′-diol 1 (BINOL) is described. The enantiomeric purity was fully maintained in the reaction. Compound 3 has been used as an entry point for the convenient chromatography-free synthesis of 3,3′,6,6′-tetra-tert-butyl BINOL 4 and 3,3′-dibromo-6,6′-di-tert-butyl BINOL 5. A straightforward route to enantiopure bisphosphites [(6,6′-R2C20H10O2)P]2[O2C20H10-6,6′-R2] [R = H 15, t-Bu 16] by simply reacting phosphorochloridite (6,6′-R2C20H10O2)PCl [R = H 20, t-Bu 6] with metallic sodium is highlighted. The identity of 15 and 16 as their selenium-oxidized products 17 and 18 (at phosphorus center) is confirmed by X-ray crystallography (17 in the enantiopure form and 18 as racemate). Various enantiopure phosphoramidites of the modified BINOL have been synthesized. It is established that even when the phosphoramidites derived from the unsusbstituted BINOL 1 fail to give an appreciable optical induction in the asymmetric reduction of acetophenone/phenacyl chloride, those derived from 3 do induce moderate chiral induction (up to 30% ee in the case for acetophenone and 43% ee in the case of phenacyl chloride), thus leaving scope for further improvement in ee for related reactions.

1 aBalaraman, Ekambaram1 aSwamy, K., C. Kumara uhttps://library.ncl.res.in/content/convenient-chromatography-free-access-enantio-pure-66%E2%80%99-di-tert-butyl-11%E2%80%99-binaphthalene-22%E2%80%9901122nas a2200157 4500008004100000245010900041210006900150260000800219300001600227490000700243520051800250100002500768700001900793700002500812856012700837 2009 eng d00aHydrophosphonylation of activated alkenes and alkynes via fluoride ion activation in ionic liquid medium0 aHydrophosphonylation of activated alkenes and alkynes via fluori cJUL a7603–76100 v653 a

A simple transition metal-free hydro/hydrothiophosphonylation of Baylis–Hillman adducts, substituted allyl bromides, allenylphosphonates and alkynes, promoted by fluoride ion in ionic liquid, is described. Clear-cut evidence for fluoride activation of the phosphite via pentacoordinate phosphorus is provided for the first time. Also, in a comparative reaction, the product obtained was different from that from the palladium catalyzed one. Structures of key products are proven by X-ray crystallography.

1 aBalaraman, Ekambaram1 aSrinivas, Venu1 aSwamy, K., C. Kumara uhttps://library.ncl.res.in/content/hydrophosphonylation-activated-alkenes-and-alkynes-fluoride-ion-activation-ionic-liquid00554nas a2200157 4500008004100000245006300041210006200104260000800166300001600174490000800190100002500198700002500223700002500248700002600273856009700299 2009 eng d00aMitsunobu and related reactions: advances and applications0 aMitsunobu and related reactions advances and applications cAPR a2551–26510 v1091 aSwamy, K., C. Kumara1 aKumar, N., N. Bhuvan1 aBalaraman, Ekambaram1 aKumar, K., V. P. Pava uhttps://library.ncl.res.in/content/mitsunobu-and-related-reactions-advances-and-applications01382nas a2200169 4500008004100000245008000041210006900121260000800190300001800198490000800216520078100224100002501005700002801030700002501058700002001083856010901103 2010 eng d00aDirect hydrogenation of amides to alcohols and amines under mild conditions0 aDirect hydrogenation of amides to alcohols and amines under mild cNOV a16756–167580 v1323 a

The selective, direct hydrogenation of amides to the corresponding alcohols and amines with cleavage of the C−N bond was discovered. The expected products of C−O cleavage are not formed (except as traces in the case of anilides). The reaction proceeds under mild pressure and neutral, homogeneous conditions using a dearomatized, bipyridyl-based PNN Ru(II) pincer complex as a catalyst. The postulated mechanism involves metal−ligand cooperation by aromatization−dearomatization of the heteroaromatic pincer core and does not involve hydrolytic cleavage of the amide. The simplicity, generality, and efficiency of this environmentally benign process make it attractive for the direct transformations of amides to alcohols and amines in good to excellent yields.

1 aBalaraman, Ekambaram1 aGnanaprakasam, Boopathy1 aShimon, Linda, J. W.1 aMilstein, David uhttps://library.ncl.res.in/content/direct-hydrogenation-amides-alcohols-and-amines-under-mild-conditions01592nas a2200181 4500008004100000245010800041210006900149260000800218300001600226490000700242520091900249100002501168700002301193700001901216700002501235700002601260856012401286 2011 eng d00aAlkynyl and phosphonyl substituted nucleobases: a case of thermally induced conformational polymorphism0 aAlkynyl and phosphonyl substituted nucleobases a case of thermal cAPR a2302–23100 v113 a

Substituted nucleobases with alkynyl and phosphonyl groups were investigated in the context of supramolecular interactions and possible use toward synthesis of nucleoside phosphonic acids (NPAs). The adeninyl compound (adeninyl-N-9)-CH2CH2CH2CH2C≡CH exhibits conformational polymorphism as revealed by X-ray structures determined at 200 and 298 K. Interestingly, in the compound (adeninyl-N-9)-(CH2)15CH3, the long aliphatic carbon chain does not show disorder. A rather unusual bending of alkyl chain, likely due to C–H···O interactions, is observed in the case of the thymine compound (thyminyl)-CH2CH2CH2C≡CH that possesses a terminal alkyne group. The powerful hydrogen bond acceptor property of the phosphoryl oxygen (P═O) does not perturb (unless assisted by other hydrogen bonding partners) the homo base-pairing in the structures of most of the phosphonyl substituted nucleobases studied.

1 aSwamy, K., C. Kumara1 aAllu, Srinivasarao1 aSrinivas, Venu1 aBalaraman, Ekambaram1 aKumar, K., V. P. Pava uhttps://library.ncl.res.in/content/alkynyl-and-phosphonyl-substituted-nucleobases-case-thermally-induced-conformational02410nas a2200193 4500008004100000245021700041210006900258260000800327300001400335490000800349520158300357100002401940700002201964700001901986700002502005700002502030700002302055856013802078 2011 eng d00aCyclodiphosph(III)azane chemistry – ylides from the reaction of [(RNH)P-N(t-Bu)]2 [R = t-Bu, i-Pr] with dimethyl maleate and chiral ansa-type derivatives from reaction of [ClP-N(t-Bu)]2 with a substituted BINOL0 aCyclodiphosphIIIazane chemistry ylides from the reaction of RNHP cJUN a374–3820 v3723 a

Use of a simple inorganic ring system with the cyclodiphosph(III)azane skeleton [e.g. [(RNH)P-N(t-Bu)]2 [R = t-Bu (7), i-Pr (8)] to probe some of the intermediates proposed in phosphine mediated organic reactions is highlighted. Thus the reaction of 7–8 with the allenylphosphine oxide Ph2P(O)C(Ph)double bond; length as m-dashCdouble bond; length as m-dashCH2 (9) affords the phosphinimines [(RNH)P(μ-N-t-Bu)2P(double bond; length as m-dashN-R)-C(double bond; length as m-dashCH2)CH(Ph)-P(O)Ph2] [R = t-Bu (10), i-Pr (11)], while a similar reaction of 7–8 with dimethyl maleate (or dimethyl fumarate) affords the ylides [(RNH)P(μ-N-t-Bu)2P(NH-R)double bond; length as m-dashC(CO2Me)-CH2(CO2Me) [R = t-Bu (18), i-Pr (19)]. The implication of such reactions on phosphine mediated organic transformations including Morita–Baylis–Hillman reaction is mentioned. In a rather rare type of situation, an unusually long phosphoryl (Pdouble bond; length as m-dashO) bond [1.538 (5) Å] as revealed the X-ray structure of {(R)-6,6′-(t-Bu)2-1,1′-(C10H5)2-2,2′-O2-}{P(O)(N-t-Bu)2-P(Se)} (27) is rationalized by means of crystallographic disorder in packing after comparing the data with that in the literature and {1,1′-(C10H6)2-2,2′-O2}{P(Se)(N-t-Bu)2-P(Se)} (29). X-ray structures of the new compounds 10–11, 18–19, 27 and 29 are discussed. Compound 10 crystallizes in the chiral space group Pca2(1) with (S)-chirality at the carbon center [–C(double bond; length as m-dashCH2)CH(Ph)-P] suggesting a case of spontaneous resolution through crystallization.

1 aSwamy, K.C., Kumara1 aGangadhararao, G.1 aSrinivas, Venu1 aKumar, N., N. Bhuvan1 aBalaraman, Ekambaram1 aChakravarty, Manab uhttps://library.ncl.res.in/content/cyclodiphosphiiiazane-chemistry-%E2%80%93-ylides-reaction-rnhp-nt-bu2-r-t-bu-i-pr-dimethyl-maleate01850nas a2200181 4500008004100000245013700041210006900178260000800247300001400255490000600269520115100275100002501426700002801451700001601479700002501495700002001520856012801540 2011 eng d00aEfficient hydrogenation of organic carbonates, carbamates, and formates indicates alternative routes to methanol based on CO2 and CO0 aEfficient hydrogenation of organic carbonates carbamates and for cJUL a609–6140 v33 a

Catalytic hydrogenation of organic carbonates, carbamates and formates is of significant interest both conceptually and practically, because these compounds can be produced from CO2 and CO, and their mild hydrogenation can provide alternative, mild approaches to the indirect hydrogenation of CO2 and CO to methanol, an important fuel and synthetic building block. Here, we report for the first time catalytic hydrogenation of organic carbonates to alcohols, and carbamates to alcohols and amines. Unprecedented homogeneously catalysed hydrogenation of organic formates to methanol has also been accomplished. The reactions are efficiently catalysed by dearomatized PNN Ru(II) pincer complexes derived from pyridine- and bipyridine-based tridentate ligands. These atom-economical reactions proceed under neutral, homogeneous conditions, at mild temperatures and under mild hydrogen pressures, and can operate in the absence of solvent with no generation of waste, representing the ultimate ‘green’ reactions. A possible mechanism involves metal–ligand cooperation by aromatization–dearomatization of the heteroaromatic pincer core.

1 aBalaraman, Ekambaram1 aGunanathan, Chidambaram1 aZhang, Jing1 aShimon, Linda, J. W.1 aMilstein, David uhttps://library.ncl.res.in/content/efficient-hydrogenation-organic-carbonates-carbamates-and-formates-indicates-alternative02558nas a2200169 4500008004100000245018200041210006900223260000800292300001600300490000700316520185500323100001602178700002502194700002002219700002002239856012902259 2011 eng d00aElectron-rich PNP- and PNN-type Ru(II) hydrido-borohydride complexes. synthesis, structure and catalytic activity towards dehydrogenation of alcohols and hydrogenation of esters0 aElectronrich PNP and PNNtype RuII hydridoborohydride complexes s cOCT a5716–57240 v303 a

Electron-rich PNP- and PNN-type ruthenium(II) hydrido borohydride pincer complexes, [RuH(BH4)(tBu-PNP)] (tBu-PNP = (2,6-bis(di-tert-butylphosphinomethyl)pyridine) (5) and [RuH(BH4)(tBu-PNN)] (tBu-PNN = 2-di-tert-butylphosphinomethyl-6-diethylaminomethylpyridine) (6), were prepared from their corresponding N2-bridged dinuclear Ru(II) complexes [(tBu-PNP)RuCl2]2(μ-N2) (3) and [(tBu-PNN)RuCl2]2(μ-N2) (4), respectively. The X-ray structure of 5 reveals a BH4– anion η2 coordinated to ruthenium through two bridging hydrides. A variable-temperature 1H NMR study of 6 exhibits interesting fluxional behavior of the BH4– ligand. Similarly, the Ru(II) hydrido borohydride complex 9, in which the BH4– moiety is coordinated in a η1 bonding mode, was obtained by reaction of [RuCl2(PPh3)(iPr-PNP)] (iPr-PNP = 2,6-bis(diisopropylphosphinomethyl)pyridine) (8) with two equivalents of NaBH4 at room temperature. The hydrido borohydride pincer complexes 5, 6, and 9 catalyze the acceptorless dehydrogenative coupling of primary alcohols to esters and the dehydrogenation of secondary alcohols to the corresponding ketones, accompanied by evolution of hydrogen gas. The reactivity follows the order 6 > 9 > 5. With the hydrido borohydride complex 6 as catalyst, high yields (up to 98%) and high turnover numbers (TON ∼1000) were obtained in the dehydrogenation of primary alcohols under mild and neutral conditions. In addition, 6 effectively catalyzes the hydrogenation of nonactivated aromatic and aliphatic esters to the corresponding alcohols with TON ∼200 under a relatively mild pressure of dihydrogen and neutral and homogeneous conditions. Thus, an efficient homogeneous catalytic system for the dehydrogenation–hydrogenation reactions of alcohols is developed, which is relevant to the current interest in hydrogen storage.

1 aZhang, Jing1 aBalaraman, Ekambaram1 aLeitus, Gregory1 aMilstein, David uhttps://library.ncl.res.in/content/electron-rich-pnp-and-pnn-type-ruii-hydrido-borohydride-complexes-synthesis-structure-and02571nas a2200193 4500008004100000245012300041210006900164260000800233300001600241490000700257520185100264100001702115700002502132700002402157700002002181700002502201700002002226856013102246 2011 eng d00aNew CNN-type ruthenium pincer NHC complexes. synthesis and catalytic activity. mild, efficient hydrogenation of esters0 aNew CNNtype ruthenium pincer NHC complexes synthesis and catalyt cJUN a3826–38330 v303 a

New pincer ruthenium complexes (2–6) based on the new bipyridine-NHC ligand 1 were prepared and studied, resulting in an efficient catalytic hydrogenation of esters to the corresponding alcohols under mild conditions. Reaction of the ligand 1 with RuH(Cl)CO(PPh3)3, followed by reaction with one equivalent of the base KHMDS, gave the mixed phosphine-NHC complex 2, incorporating a C–H-activated bipyridine ligand. Complex 2 has an octahedral structure containing two phosphorus atoms trans to each other, a hydride trans to the NHC ligand, and CO trans to the C–H-activated carbon of the bipyridine ligand. Using the precursor complex Ru(p-cymene)Cl2(CO), reaction with 1 followed by treatment of the intermediate product with one equivalent of KHMDS resulted in formation of the dichloride pincer complexes 3a and 3b, which are in equilibrium, as indicated by variable-temperature 1H NMR. Complex 3a is an octahedral, neutral, and symmetric complex with the CO ligand positioned trans to the central pyridine group of the pincer ligand and the two chlorides trans to each other, as indicated by single-crystal X-ray diffraction. Complex 3b is cationic, with an outer-sphere chloride. Reaction of the NHC ligand 1 with LiHMDS at low temperature followed by addition of RuH(Cl)CO(PPh3)3 resulted in the mixed phosphine-NHC complex 4, which has an octahedral structure containing phosphorus trans to the hydride, a CO trans to the NHC ligand, and an outer-sphere chloride. Chloride substitution by BArF– gave the X-ray-characterized complex 5. Deprotonation of complex 4 with KHMDS resulted in formation of the dearomatized complex 6. The in situ prepared 6 (from complex 4 and an equivalent of base) is among the best catalysts known for the hydrogenation of nonactivated esters to the corresponding alcohols under mild conditions.

1 aFogler, Eran1 aBalaraman, Ekambaram1 aBen-David, Yehoshoa1 aLeitus, Gregory1 aShimon, Linda, J. W.1 aMilstein, David uhttps://library.ncl.res.in/content/new-cnn-type-ruthenium-pincer-nhc-complexes-synthesis-and-catalytic-activity-mild-efficient01705nas a2200193 4500008004100000245019700041210006900238260000800307300001800315490000700333520090500340100002401245700001901269700002501288700002501313700002401338700001901362856013001381 2011 eng d00aPhotocatalytic splitting of CS2 to a carbon-sulfur polymer and S8 catalyzed by a bimetallic ruthenium(II) compound with a tertiary amine binding site - towards photocatalytic splitting of CO2?0 aPhotocatalytic splitting of CS2 to a carbonsulfur polymer and S8 cOCT a11273–112750 v503 a

The catalytic photocleavage of CS2 to S8 and a (CxSy)n polymer with visible light using a dinuclear ruthenium(II) compound with a bipyridine units for photoactivity and a vicinal tertiary amine binding site for CS2 activation was studied. The catalyst was characterized by X-ray diffraction, 1H NMR, and 13C NMR, ESI-MS and elemental analysis. CS2 photocleavage was significant (240 turnovers, 20 h) to yield isolable S8 and a (CxSy)n polymer. A mononuclear catalyst or one without an amine binding site showed significantly less activity. XPS of the (CxSy)n polymer showed a carbon/sulfur ratio ∼1.5–1.6 indicating that in part both C–S bonds of CS2 had been cleaved. Catalyst was also included within the polymer. The absence of peaks in the 1H NMR verified the (CxSy)n nature of the polymer, while 13C NMR and IR indicated that the polymer had multiple types of C–S and C–C bonds.

1 aLivanov, Konstantin1 aMadhu, Vedichi1 aBalaraman, Ekambaram1 aShimon, Linda, J. W.1 aDiskin-Posner, Yael1 aNeumann, Ronny uhttps://library.ncl.res.in/content/photocatalytic-splitting-cs2-carbon-sulfur-polymer-and-s8-catalyzed-bimetallic-rutheniumii01100nas a2200169 4500008004100000245015500041210006900196260000800265300001800273490000800291520040300299100002800702700002500730700002400755700002000779856013100799 2011 eng d00aSynthesis of peptides and pyrazines from beta-aminoalcohols via extrusion of H2 catalyzed by ruthenium pincer complexes. ligand controlled selectivity0 aSynthesis of peptides and pyrazines from betaaminoalcohols via e cOCT a12448–124520 v1233 a

Bitte wählen: Die Wahl des Katalysators, eines Ru-Pinzettenkomplexes, bestimmt, ob Peptide oder Pyrazine aus β-Aminoalkoholen entstehen: Der PNN-Komplex 1 führt, je nach Substituent R (siehe Schema), zu linearem Polyalanin oder zu cyclischen Dipeptiden, der PNP-Komplex 2 katalysiert die Bildung von Pyrazinen. Die Reaktionen finden in homogener Lösung unter neutralen Bedingungen statt.

1 aGnanaprakasam, Boopathy1 aBalaraman, Ekambaram1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/synthesis-peptides-and-pyrazines-beta-aminoalcohols-extrusion-h2-catalyzed-ruthenium-pincer01003nas a2200157 4500008004100000245008500041210006900126260000800195300001800203490000800221520043300229100002500662700002400687700002000711856011400731 2011 eng d00aUnprecedented catalytic hydrogenation of urea derivatives to amines and methanol0 aUnprecedented catalytic hydrogenation of urea derivatives to ami cDEC a11906–119090 v1233 a

Indirekte CO2-Hydrierung: Eine Hydrierung von Harnstoffen zu Aminen und Methanol (siehe Bild) wird durch einen RuII-Pinzettenkomplex mit dreizähnigem bipyridinbasiertem PNN-Liganden katalysiert und verläuft unter milden, neutralen Bedingungen bei einem H2-Druck von 13.6 atm. Da sich Harnstoffderivate ausgehend von CO2 erhalten lassen, ermöglicht dieser Ansatz die indirekte Hydrierung von Kohlendioxid zu Methanol.

1 aBalaraman, Ekambaram1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/unprecedented-catalytic-hydrogenation-urea-derivatives-amines-and-methanol00902nas a2200157 4500008004100000245007700041210006900118260000800187300001400195490000700209520036100216100002500577700001700602700002000619856010500639 2012 eng d00aEfficient hydrogenation of biomass derived cyclic di-esters to 1,2-diols0 aEfficient hydrogenation of biomass derived cyclic diesters to 12 cOCT a1111-11130 v483 a

The unprecedented homogeneous hydrogenation of cyclic di-esters, in particular biomass-derived glycolide and lactide, to the corresponding 1,2-diols is catalyzed by Ru(II) PNN (1) and Ru(II) CNN (2) pincer complexes under mild hydrogen pressure and (in the case of 1) neutral conditions. No racemization was observed when a chiral di-ester was used.

1 aBalaraman, Ekambaram1 aFogler, Eran1 aMilstein, David uhttps://library.ncl.res.in/content/efficient-hydrogenation-biomass-derived-cyclic-di-esters-12-diols01874nas a2200157 4500008004100000245013500041210006900176260000800245520121900253100002001472700002501492700002801517700002801545700001601573856012701589 2012 eng d00aNovel ruthenium complexes and their uses in processes for formation and/or hydrogenation of esters, amides and derivatives thereof0 aNovel ruthenium complexes and their uses in processes for format cOCT3 a

The present invention relates to novel Ruthenium complexes and related borohydride complexes, and their use for (1) hydrogenation of amides (including polyamides) to alcohols and amines; (2) preparing amides from alcohols with amines (including preparing polyamides (e.g., polypeptides) by reacting dialcohols and diamines or by polymerization of amino alcohols); (3) hydrogenation of esters to alcohols (including hydrogenation of cyclic esters (lactones), cyclic di-esters (di-lactones) or polyesters); (4) hydrogenation of organic carbonates (including polycarbonates) to alcohols and of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (5) dehydrogenative coupling of alcohols to esters; (6) hydrogenation of secondary alcohols to ketones; (7) amidation of esters (synthesis of amides from esters and amines); (8) acylation of alcohols using esters; (9) coupling of alcohols with water to form carboxylic acids; and (10) dehydrogenation of beta-amino alcohols to form pyrazines. The present invention further relates to novel uses of certain pyridine Ruthenium complexes.

1 aMilstein, David1 aBalaraman, Ekambaram1 aGunanathan, Chidambaram1 aGnanaprakasam, Boopathy1 aZhang, Jing uhttps://library.ncl.res.in/content/novel-ruthenium-complexes-and-their-uses-processes-formation-andor-hydrogenation-esters00981nas a2200181 4500008004100000245013100041210006900172260000800241300001600249490000800265520028300273100002200556700002500578700002800603700002400631700002000655856012400675 2012 eng d00aRuthenium pincer-catalyzed cross-dehydrogenative coupling of primary alcohols with secondary alcohols under neutral conditions0 aRuthenium pincercatalyzed crossdehydrogenative coupling of prima cSEP a2403–24060 v3543 a

Cross-dehydrogenative coupling of primary alcohols with secondary alcohols to obtain mixed esters with the liberation of molecular hydrogen is achieved in high yield and good selectivity under neutral conditions, using a bipyridyl-based PNN ruthenium(II) pincer catalyst.

1 aSrimani, Dipankar1 aBalaraman, Ekambaram1 aGnanaprakasam, Boopathy1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/ruthenium-pincer-catalyzed-cross-dehydrogenative-coupling-primary-alcohols-secondary02002nas a2200169 4500008004100000245007400041210006900115260000800184300001600192490000700208520142300215100002801638700002501666700002801691700002001719856009301739 2012 eng d00aSynthesis of polyamides from diols and diamines with liberation of H20 aSynthesis of polyamides from diols and diamines with liberation  cMAY a1755–17650 v503 a

The amidation reaction based on catalytic coupling of alcohols with amines previously reported by us, using the pincer complexes 1 and 2 as catalysts, was applied to the generation of polyamides from nonactivated diols and diamines. A range of polymers was prepared, with Mn up to 26.9 kDa. Unlike the traditional syntheses of polyamides based on carboxylic acid derivatives, which require the use of toxic reagents and generate stoichiometric amounts of waste, this process generates only molecular hydrogen as byproduct. Both aromatic and aliphatic diols and diamines were used. Gel permeation chromatography measurements of the dimethylformamide-soluble polymers and thermal studies of the polyamides were performed. Matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) spectra are also reported. Thermogravimetric analyses studies indicate that the aromatic polyamides (with the exception of the pyridine-based polyamide) are more thermally stable than the aliphatic ones. This general, environmentally benign method for the synthesis of polyamides is homogeneously catalyzed under neutral conditions by dearomatized ruthenium-pincer complexes 1 and 2 and proceeds in 1,4-dioxane under an inert atmosphere. Conditions for polyamidation in the absence of solvent are also reported, using the pincer complex 2 as catalyst. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

1 aGnanaprakasam, Boopathy1 aBalaraman, Ekambaram1 aGunanathan, Chidambaram1 aMilstein, David uhttps://library.ncl.res.in/content/synthesis-polyamides-diols-and-diamines-liberation-h201646nas a2200169 4500008004100000245011600041210006900157260000800226520097300234100002001207700002801227700002401255700002501279700002801304700001601332856012801348 2012 eng d00aUse of ruthenium complexes for formation and/or hydrogenation of amides and related carboxylic acid derivatives0 aUse of ruthenium complexes for formation andor hydrogenation of  cMAR3 a

A process for preparing amides by reacting a primary amine and a primary alcohol in the presence of a Ruthenium complex to generate the amide and molecular hydrogen. Primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only byproduct) in high yields and high turnover numbers. Also disclosed are processes for hydrogenation of amides to alcohols and amines; hydrogenation of organic carbonates to alcohols; hydrogenation of carbamates or urea derivatives to alcohols and amines; amidation of esters; acylation of alcohols using esters; coupling of alcohols with water and a base to form carboxylic acids; dehydrogenation of beta-amino alcohols to form pyrazines and cyclic dipeptides; and dehydrogenation of secondary alcohols to ketones. These reactions are catalyzed by a Ruthenium complex which is based on a dearomatized PNN-type ligand of formula A1 or precursors thereof of formulae A2 or A3.

1 aMilstein, David1 aGunanathan, Chidambaram1 aBen-David, Yehoshoa1 aBalaraman, Ekambaram1 aGnanaprakasam, Boopathy1 aZhang, Jing uhttps://library.ncl.res.in/content/use-ruthenium-complexes-formation-andor-hydrogenation-amides-and-related-carboxylic-acid01390nas a2200169 4500008004100000245011100041210006900152260000800221300001400229490000600243520076000249100002501009700002001034700002001054700002001074856012601094 2013 eng d00aCatalytic transformation of alcohols to carboxylic acid salts and H2 using water as the oxygen atom source0 aCatalytic transformation of alcohols to carboxylic acid salts an cFEB a122–1250 v53 a

The oxidation of alcohols to carboxylic acids is an important industrial reaction used in the synthesis of bulk and fine chemicals. Most current processes are performed by making use of either stoichiometric amounts of toxic oxidizing agents or the use of pressurized dioxygen. Here, we describe an alternative dehydrogenative pathway effected by water and base with the concomitant generation of hydrogen gas. A homogeneous ruthenium complex catalyses the transformation of primary alcohols to carboxylic acid salts at low catalyst loadings (0.2 mol%) in basic aqueous solution. A consequence of this finding could be a safer and cleaner process for the synthesis of carboxylic acids and their derivatives at both laboratory and industrial scales.

1 aBalaraman, Ekambaram1 aKhaskin, Eugene1 aLeitus, Gregory1 aMilstein, David uhttps://library.ncl.res.in/content/catalytic-transformation-alcohols-carboxylic-acid-salts-and-h2-using-water-oxygen-atom01291nas a2200181 4500008004100000245016700041210006900208260000800277300001600285490000800301520056500309100002200874700002500896700001300921700002400934700002000958856013100978 2013 eng d00aFormation of tertiary amides and H2 by dehydrogenative coupling of primary alcohols with secondary amines catalyzed by ruthenium bipyridine-based pincer complexes0 aFormation of tertiary amides and H2 by dehydrogenative coupling  cSEP a2525–25300 v3553 a

Dehydrogenative coupling of primary alcohols with secondary amines to form tertiary amides and dihydrogen (H2) is efficiently catalyzed by bipyridyl-based ruthenium pincer complexes (0.2–1 mol%) under neutral conditions (in case of the dearomatized complexes), or with added catalytic amount of base. The reaction is sensitive to steric hindrance; in the case of amidation of bulky secondary amines a less sterically hindered complex is more efficient. Selective acylation of primary amines in the presence of secondary amines was also demonstrated.

1 aSrimani, Dipankar1 aBalaraman, Ekambaram1 aHu, Peng1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/formation-tertiary-amides-and-h2-dehydrogenative-coupling-primary-alcohols-secondary-amines02343nas a2200193 4500008004100000245016200041210006900203260000800272300001600280490000700296520155600303100003301859700002501892700002401917700002001941700002501961700002001986856014302006 2013 eng d00aPNN-Ru pincer complexes based on phosphinated 2,2’-dipyridinemethane- and 2,2’-oxobispyridine. metal-ligand cooperation in cyclometallation and catalysis0 aPNNRu pincer complexes based on phosphinated 22 dipyridinemethan cMAY a2973–29820 v323 a

The synthesis of novel PNN ruthenium pincer complexes based on 2,2′-dipyridinemethane phosphine derivatives, as well as on 2,2′-oxobispyridine phosphine ligands, and their reactivity toward dearomatization and cyclometalation are described. The dearomatized compounds 7a,b undergo cyclometalation to yield complexes 8a,b. In order for cyclometalation to proceed, the coordination sphere around the Ru center has to rearrange, and this depends on the flexibility of the system, showing that the cyclometalation is qualitatively faster in the case of the dimethyl derivative 7a than in the case of the spyrocyclopentyl derivative 7b. The cyclometalation occurs diastereoselectively and leads to only one diastereomer of the cyclometalated compounds. In the case of the 2,2′-oxobispyridine complex 6c, the dearomatized complex was too unstable to be isolated; however it was possible to isolate and characterize a stable dicarbonyl-dearomatized ruthenium(II) complex, 9c, when the deprotonation was performed under a CO atmosphere. Dearomatization of 6a under CO also led to dicarbonyl-dearomatized ruthenium(II) complex 9a, which slowly rearranged into the dicarbonyl-aromatized ruthenium(0) complex 10a. These complexes were tested in catalytic alcohol–amine coupling, esterification of primary alcohols, and hydrogenation of secondary amides. Moderate activity was observed in hydrogenation of amides to alcohols and amines and low activity in the other transformations, owing mainly to the formation of stable cyclometalated compounds.

1 aBarrios-Francisco, Rigoberto1 aBalaraman, Ekambaram1 aDiskin-Posner, Yael1 aLeitus, Gregory1 aShimon, Linda, J. W.1 aMilstein, David uhttps://library.ncl.res.in/content/pnn-ru-pincer-complexes-based-phosphinated-22%E2%80%99-dipyridinemethane-and-22%E2%80%99-oxobispyridine01807nas a2200217 4500008004100000245016300041210006900204260000800273300001600281490000700297520098300304100001901287700001501306700001901321700002501340700002401365700002501389700002401414700002001438856013101458 2013 eng d00aStepwise metal-ligand cooperation via a reversible aromatization-deconjugation-sequence in ruthenium complexes with a tetradentate phenanthroline-based ligand0 aStepwise metalligand cooperation via a reversible aromatizationd cMAR a3407–34140 v193 a

The synthesis and reactivity of ruthenium complexes containing the tetradentate phenanthroline-based phosphine ligand 2,9-bis((di-tert-butylphosphino)methyl)-1,10-phenanthroline (PPhenP) is described. The hydrido chloro complex [RuHCl(PPhenP)] (2) undergoes facile dearomatization upon deprotonation of the benzylic position, to give [RuH(PPhenP-H)] (4). Addition of dihydrogen to 4 causes rearomatization of the phenanthroline moiety to trans-[Ru(H)2(PPhenP)] (5), followed by hydrogenation of an aromatic heterocycle in the ligand backbone, to give a new dearomatized and deconjugated complex [RuH(PPhenP*-H)] (6). These aromatization/deconjugation steps of the coordinated ligand were demonstrated to be reversible and operative in the dehydrogenation of primary alcohols without the need for a hydrogen acceptor. This aromatization/deconjugation sequence constitutes an unprecedented mode of a stepwise cooperation between the metal center and the coordinated ligand.

1 aLanger, Robert1 aFuchs, Ido1 aVogt, Matthias1 aBalaraman, Ekambaram1 aDiskin-Posner, Yael1 aShimon, Linda, J. W.1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/stepwise-metal-ligand-cooperation-reversible-aromatization-deconjugation-sequence-ruthenium02868nas a2200241 4500008004100000245012800041210006900169260000800238300001600246490000700262520200600269100001702275700001902292700001902311700002802330700002502358700002402383700002002407700002502427700002402452700002002476856013002496 2013 eng d00aSynthesis, structures, and dearomatization by deprotonation of iron complexes featuring bipyridine-based PNN pincer ligands0 aSynthesis structures and dearomatization by deprotonation of iro cJUL a9636–96490 v523 a

The synthesis and characterization of new iron pincer complexes bearing bipyridine-based PNN ligands is reported. Three phosphine-substituted pincer ligands, namely, the known tBu-PNN (6-((di-tert-butylphosphino)methyl)-2,2′-bipyridine) and the two new iPr-PNN (6-((di-iso-propylphosphino)methyl)-2,2′-bipyridine) and Ph-PNN (6-((diphenylphosphino)methyl)-2,2′-bipyridine) ligands were synthesized and studied in ligation reactions with iron(II) chloride and bromide. These reactions lead to the formation of two types of complexes: mono-chelated neutral complexes of the type [(R-PNN)Fe(X)2] and bis-chelated dicationic complexes of the type [(R-PNN)2Fe]2+. The complexes [(R-PNN)Fe(X)2] (1: R = tBu, X = Cl, 2: R = tBu, X = Br, 3: R = iPr, X = Cl, and 4: R = iPr, X = Br) are readily prepared from reactions of FeX2 with the free R-PNN ligand in a 1:1 ratio. Magnetic susceptibility measurements show that these complexes have a high-spin ground state (S = 2) at room temperature. Employing a 2-fold or higher excess of iPr-PNN, diamagnetic hexacoordinated dicationic complexes of the type [(iPr-PNN)2Fe](X)2 (5: X = Cl, and 6: X = Br) are formed. The reactions of Ph-PNN with FeX2 in a 1:1 ratio lead to similar complexes of the type [(Ph-PNN)2Fe](FeX4) (7: X = Cl, and 8: X = Br). Single crystal X-ray studies of 1, 2, 4, 6, and 8 do not indicate electron transfer from the FeII centers to the neutral bipyridine unit based on the determined bond lengths. Density functional theory (DFT) calculations were performed to compare the relative energies of the mono- and bis-chelated complexes. The doubly deprotonated complexes [(R-PNN*)2Fe] (9: R = iPr, and 10: R = Ph) were synthesized by reactions of the dicationic complexes 6 and 8 with KOtBu. The dearomatized nature of the central pyridine of the pincer ligand was established by X-ray diffraction analysis of single crystals of 10. Reactivity studies show that 9 and 10 have a slightly different behavior in protonation reactions.

1 aZell, Thomas1 aLanger, Robert1 aIron, Mark, A.1 aKonstantinovski, Leonid1 aShimon, Linda, J. W.1 aDiskin-Posner, Yael1 aLeitus, Gregory1 aBalaraman, Ekambaram1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/synthesis-structures-and-dearomatization-deprotonation-iron-complexes-featuring-bipyridine02120nas a2200289 4500008004100000020004100041022001400082245007300096210006900169260026000238300001000498490000700508520099400515653001101509653001901520653001101539653001301550653001801563653002901581653002101610653001401631100002501645700002001670700001601690700002001706856010401726 2014 eng d a978-3-319-08482-4; 978-3-319-08481-7 a1436-600200aHydrogenation of polar bonds catalysed by ruthenium-pincer complexes0 aHydrogenation of polar bonds catalysed by rutheniumpincer comple aHEIDELBERGER PLATZ 3, D-14197 BERLIN, GERMANYbIEEE Commun Soc; IEEE Syst Man & Cybernet Soc; Galgotias Coll Engn & Technol; Hochschule Offenburg Univ Appl Sci; Int Neural Network Soc; India Chapter & Res Publishing Serv; Madhyam; WizIQ; ICACCI; IEEEcMAR a19-430 v483 a

Catalytic hydrogenation of polar bonds using molecular hydrogen is an important, atom-economical synthetic reaction. Classical reduction methods of polar bond often require reactive metal-hydride reagents in stoichiometric amount and produce copious waste. Hydrogenation of carbonyl compounds in particular provides `green' approaches to synthetically important building blocks, such as alcohols and amines. We have designed and synthesized several ruthenium-based pincer catalysts for unprecedented hydrogenation reactions including: (1) amides to alcohols and amines, (2) biomass-derived di-esters to 1,2-diols and (3) CO2 and CO derivatives to methanol. These atom-economical reactions operate under neutral, homogeneous conditions, at mild temperatures, mild hydrogen pressures, and can operate in absence of solvent with no generation of waste. The postulated mechanisms involve metal-ligand cooperation (MLC) by aromatization-dearomatization of the heteroaromatic pincer core.

10aAmides10aCarbon dioxide10aEsters10aHydrogen10aHydrogenation10aMetal-ligand cooperation10aPincer complexes10aruthenium1 aBalaraman, Ekambaram1 aMilstein, David1 aBruneau, C.1 aDixneuf, P., H. uhttps://library.ncl.res.in/content/hydrogenation-polar-bonds-catalysed-ruthenium-pincer-complexes-001285nas a2200241 4500008004100000022001400041245010700055210006900162260005700231300001200288490000800300520042200308653001200730653001200742653002500754653002200779653002000801100002500821700002200846700002400868700002000892856013100912 2015 eng d a1011-372X00aDirect synthesis of secondary amines from alcohols and ammonia catalyzed by a ruthenium pincer complex0 aDirect synthesis of secondary amines from alcohols and ammonia c a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcJAN a139-1440 v1453 a

Efficient and selective direct synthesis of secondary amines from primary alcohols and ammonia with liberation of water has been achieved, with high turnover numbers and with no generation of waste. In case of benzylic alcohols, imines rather than amines are obtained. This atom economical, environmentally benign reaction is homogenously catalyzed by a well-defined bipyridine based Ru(II)-PNN pincer complex.

10aAlcohol10aAmmonia10aHomogenous catalysis10aRu-pincer complex10aSecondary amine1 aBalaraman, Ekambaram1 aSrimani, Dipankar1 aDiskin-Posner, Yael1 aMilstein, David uhttps://library.ncl.res.in/content/direct-synthesis-secondary-amines-alcohols-and-ammonia-catalyzed-ruthenium-pincer-complex-001913nas a2200193 4500008004100000022001400041245011000055210006900165260009000234300002500324490000600349520110800355100002401463700002401487700003001511700002401541700002501565856012901590 2015 eng d a2041-172300aReversed reactivity of anilines with alkynes in the rhodium-catalysed C-H activation/carbonylation tandem0 aReversed reactivity of anilines with alkynes in the rhodiumcatal aMACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLANDbNATURE PUBLISHING GROUPcOCT aArticle Number: 85910 v63 a

Development of multicatalytic approach consisting of two or more mechanistically distinct catalytic steps using a single-site catalyst for rapid and straightforward access of structurally complex molecules under eco-benign conditions has significance in contemporary science. We have developed herein a rhodium-catalysed C-H activation strategy which uses an unprotected anilines and an electron-deficient alkynes to C-C bonded products as a potential intermediate in contrast to the archetypical C-N bonded products with high levels of regioselectivity. This is followed by carbonylation of C-H bond activated intermediate and subsequent annulation into quinolines has been described. This rhodium-catalysed auto-tandem reaction operates under mild, environmentally benign conditions using water as the solvent and CO surrogates as the carbonyl source with the concomitant generation of hydrogen gas. The strategy may facilitate the development of new synthetic protocols for the efficient and sustainable production of chemicals in an atom-economic way from simple, abundant starting materials.

1 aMidya, Siba, Prasad1 aSahoo, Manoj, Kumar1 aLandge, Vinod, Gokulkrish1 aRajamohanan, P., R.1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/reversed-reactivity-anilines-alkynes-rhodium-catalysed-c-h-activationcarbonylation-tandem00771nas a2200157 4500008004100000245005800041210005600099260000800155300001400163490000600177520026100183100003000444700002400474700002500498856009000523 2015 eng d00aReverse-hydroformylation: a missing reaction explored0 aReversehydroformylation a missing reaction explored cAUG a1422-14240 v23 a

Recent progress in transition-metal catalysed acceptor- and acceptorless-reverse hydroformylation of aldehydes for the conversion of olefins has been discussed. The aldehyde feedstock serves as a source for production of syngas and valuable alkenes.

1 aNandakumar, Avanashiappan1 aSahoo, Manoj, Kumar1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/reverse-hydroformylation-missing-reaction-explored01418nas a2200181 4500008004100000022001400041245009500055210006900150260007500219300001600294490000700310520068400317100003001001700002401031700003001055700002501085856012601110 2015 eng d a1433-785100aTransition-metal-catalyzed hydrogen-transfer annulations: access to heterocyclic scaffolds0 aTransitionmetalcatalyzed hydrogentransfer annulations access to  aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcSEP a11022-110340 v543 a

The ability of hydrogen-transfer transition-metal catalysts, which enable increasingly rapid access to important structural scaffolds from simple starting materials, has led to a plethora of research efforts on the construction of heterocyclic scaffolds. Transition-metal-catalyzed hydrogen-transfer annulations are environmentally benign and highly atom-economical as they release of water and hydrogen as by-product and utilize renewable feedstock alcohols as starting materials. Recent advances in this field with respect to the annulations of alcohols with various nucleophilic partners, thus leading to the formation of heterocyclic scaffolds, are highlighted herein.

1 aNandakumar, Avanashiappan1 aMidya, Siba, Prasad1 aLandge, Vinod, Gokulkrish1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/transition-metal-catalyzed-hydrogen-transfer-annulations-access-heterocyclic-scaffolds00940nas a2200181 4500008004100000245008000041210006900121260000800190300001600198490000700214520030700221100003000528700002400558700002400582700002000606700002500626856010700651 2015 eng d00aWell-defined palladium(II) complexes for ligand enabled C(sp3)-alkynylation0 aWelldefined palladiumII complexes for ligand enabled Csp3alkynyl cJUL a15382-153860 v443 a

The first example of ligand-enabled C(sp3)-alkynylation of 8-methylquinoline is reported. The reaction is catalysed by well-defined Pd(II) complexes. The present C(sp3)-alkynylation has a broad substrate scope as well as functional group tolerance and proceeds efficiently under mild conditions.

1 aLandge, Vinod, Gokulkrish1 aSahoo, Manoj, Kumar1 aMidya, Siba, Prasad1 aJaiswal, Garima1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/well-defined-palladiumii-complexes-ligand-enabled-csp3-alkynylation00978nas a2200157 4500008004100000245008100041210007100122260000800193300001400201490000700215520040800222100003000630700002000660700002500680856011500705 2016 eng d00aCobalt-catalyzed bis-alkynylation of amides via double C–H bond activation0 aCobaltcatalyzed bisalkynylation of amides via double C–H bond ac cFEB a812–8150 v183 a

The first example of cobalt-catalyzed selective bis-alkynylation of amides via double C–H bond activation with the directing assistance of a removable bidentate auxiliary is reported. The developed alkynylation strategy is simple, efficient, and tolerant of various functional groups including ether, amine, halides, and heterocyclic motifs. The reaction can be scaled up under mild conditions.

1 aLandge, Vinod, Gokulkrish1 aJaiswal, Garima1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/cobalt-catalyzed-bis-alkynylation-amides-double-c%E2%80%93h-bond-activation01330nas a2200193 4500008004100000245008000041210007100121260000800192300001400200490000700214520048400221653019300705100003000898700002400928700002000952700002300972700002500995856011601020 2016 eng d00aExpedient cobalt-catalyzed C–H alkynylation of (enantiopure) benzylamines0 aExpedient cobaltcatalyzed C–H alkynylation of enantiopure benzyl cOCT a5252-52550 v183 a

A unified strategy for cobalt-catalyzed ortho-C-H bond alkynylation of benzylamines is reported. Simple, commercially available CoBr2 was used as a cobalt source. The developed alkynylation strategy is robust and efficient and has a broad substrate scope including 1 degrees, 2 degrees, and 3 degrees benzylamines. The mechanistic study shows that C-H bond cleavage is reversible, and the kinetic study illustrates that the rate of reaction depends solely on the catalyst.

10aTerminal Alkynes; Bond Activation; Directed Functionalization;Aminoquinoline Benzamides; Ortho-C(Sp(2))-H Bonds; Mechanistic Insights; Selective Access; Carbon-Hydrogen; Nickel; Annulation1 aLandge, Vinod, Gokulkrish1 aMidya, Siba, Prasad1 aRana, Jagannath1 aShinde, Dinesh, R.1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/expedient-cobalt-catalyzed-c%E2%80%93h-alkynylation-enantiopure-benzylamines01259nas a2200193 4500008004100000245015300041210006900194260000800263300001400271490000600285520048300291100003000774700002500804700002000829700002400849700002400873700002500897856014300922 2016 eng d00aNickel-catalyzed direct alkynylation of C(sp2)-H bonds of amides: an “inverse sonogashira strategy” to ortho-alkynylbenzoic acids. just accepted0 aNickelcatalyzed direct alkynylation of Csp2H bonds of amides an  cOCT a1946-19510 v63 a

Nickel-catalyzed direct alkynylation of C(sp2)–H bonds of amides using commercially available, inexpensive 8-aminoquinoline as a removable bidentate directing group is described. The present ortho-alkynylation has a broad substrate scope, functional group tolerance and high regiocontrol, and can be scaled up. The efficiency and selectivity of this strategy provide sustainable routes to a diverse array of ortho-alkynylbenzoic acids under Ni(II)-catalyzed conditions.

1 aLandge, Vinod, Gokulkrish1 aShewale, Chinmay, H.1 aJaiswal, Garima1 aSahoo, Manoj, Kumar1 aMidya, Siba, Prasad1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/nickel-catalyzed-direct-alkynylation-csp2-h-bonds-amides-%E2%80%9Cinverse-sonogashira-strategy%E2%80%9D01188nas a2200169 4500008004100000245011900041210006900160260000800229300001400237490000700251520053500258100002000793700003000813700002300843700002500866856012700891 2016 eng d00aSustainable Iron-catalyzed direct imine formation by acceptorless dehydrogenative coupling of alcohols with amines0 aSustainable Ironcatalyzed direct imine formation by acceptorless cMAY a3232-32380 v183 a

The Acceptorless Dehydrogenative Coupling (ADC) of alcohols with amines is reported using a heterogeneous Fe-catalyst. The reaction operates under mild conditions with the liberation of dihydrogen and water as the byproducts. The developed ADC strategy is simple, efficient, exhibits wide functional group tolerance and can be scaled up. The present catalytic approach possesses a dual role; acting as a catalyst as well as being magnetically separable. The sustainable reuse of a heterogeneous iron catalyst is also shown.

1 aJaiswal, Garima1 aLandge, Vinod, Gokulkrish1 aJagadeesan, Dinesh1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/sustainable-iron-catalyzed-direct-imine-formation-acceptorless-dehydrogenative-coupling01693nas a2200169 4500008004100000245007500041210006900116260000800185300002500193490000600218520110700224100002001331700002201351700002301373700002501396856010201421 2017 eng d00aIron-based nanocatalyst for the acceptorless dehydrogenation reactions0 aIronbased nanocatalyst for the acceptorless dehydrogenation reac cDEC aArticle Number: 21470 v83 aDevelopment of sustainable catalytic systems for fundamentally important synthetic transformations and energy storage applications is an intellectually stimulating challenge. Catalytic dehydrogenation of feedstock chemicals, such as alcohols and amines to value-added products with the concomitant generation of dihydrogen is of much interest in the context of hydrogen economy and is an effective alternative to the classical oxidation reactions. Despite a number of homogeneous catalysts being identified for the acceptorless dehydrogenation, the use of high price and limited availability of precious metals and poor recovery of the catalyst have spurred interest in catalysis with more earth-abundant alternatives, especially iron. However, no report has described a reusable iron-based heterogeneous catalyst for oxidant-free and acceptorless dehydrogenation reactions. Here we replace expensive noble metal catalysts with an inexpensive, benign, and sustainable nanoscale iron catalyst for the efficient acceptorless dehydrogenation of N-heterocycles and alcohols with liberation of hydrogen gas.1 aJaiswal, Garima1 aLandge, Vinod, G.1 aJagadeesan, Dinesh1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/iron-based-nanocatalyst-acceptorless-dehydrogenation-reactions02097nas a2200169 4500008004100000245010400041210006900145260000800214300001400222490000600236520146300242100002501705700003001730700002001760700002101780856012601801 2017 eng d00aIron-catalyzed dehydrogenation reactions and their applications in sustainable energy and catalysis0 aIroncatalyzed dehydrogenation reactions and their applications i cAUG a3177-31950 v73 aInspired by nature, chemists have designed new catalysts in the pursuit of selective bond activation and chemical transformations. Emergent biological systems often use earth-abundant first-row transition elements as catalytically active sites to facilitate specific and highly selective chemical processes. The design of a new catalytic system based on abundant and inexpensive catalysts, particularly the iron-based catalysts, for fundamentally significant synthetic transformations under environmentally benign conditions is an important paradigm in chemical synthesis. In recent times, iron-based catalytic systems have shown unprecedented reactivity in the acceptorless dehydrogenation reactions of feedstock chemicals, with the liberation of molecular hydrogen as the by-product, and have enabled greener chemical synthetic methods and alternative energy storage systems. Indeed, it has been demonstrated that the proper design of iron catalysts by judiciously choosing ligands, can aid in the development of new sustainable energy storage systems and catalysis. This tutorial review focuses on the recent development of iron-based dehydrogenation reactions of fundamentally important feedstock, as a route to sustainable chemical synthesis and energy storage applications. The emerging area of the iron-based dehydrogenation strategy provides an opportunity to make industrially applicable, cost-effective and environmentally benign catalytic systems.1 aBalaraman, Ekambaram1 aNandakumar, Avanashiappan1 aJaiswal, Garima1 aSahoo, Manoj, K. uhttps://library.ncl.res.in/content/iron-catalyzed-dehydrogenation-reactions-and-their-applications-sustainable-energy-and01060nas a2200181 4500008004100000245010800041210006900149260000800218300001400226490000700240520039500247100002000642700002000662700002000682700002100702700002500723856013000748 2017 eng d00aMetal-free radical trifluoromethylation of beta-nitroalkenes through visible-light photoredox catalysis0 aMetalfree radical trifluoromethylation of betanitroalkenes throu cJUN a6760-67630 v533 aA catalytic method for functional group interconversion is immensely important in modern sciences. Here, we report an efficient catalytic conversion of nitroalkenes to highly stereoselective 1-trifluoromethylalkenes at room temperature. This unprecedented metal-free photocatalytic strategy is simple and operates under visible-light irradiation using the commercially available CF3 source.1 aMidya, Siba, P.1 aRana, Jagannath1 aAbraham, Thomas1 aAswin, Bhaskaran1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/metal-free-radical-trifluoromethylation-beta-nitroalkenes-through-visible-light-photoredox01111nas a2200169 4500008004100000245006400041210006300105260000800168300001400176490000800190520054700198100002600745700001800771700003100789700002500820856009600845 2017 eng d00aNickel-catalyzed direct synthesis of dialkoxymethane ethers0 aNickelcatalyzed direct synthesis of dialkoxymethane ethers cAUG a1153-11590 v1293 aA simple and efficient method for the preparation of dialkoxymethane ethers (oxymethylene ethers) from alcohols and paraformaldehyde in the presence of commercially available nickel(II) salt is described. The reaction proceeds readily under neutral, solvent-free conditions using paraformaldehyde as a C-1 source. The present strategy has a broad substrate scope including aliphatic (both primary and secondary) and aromatic alcohols and provides a benign method for the preparation of symmetrical dialkoxymethanes in good yields (up to 89%).1 aSubaramanian, Murugan1 aBera, Abhijit1 aPrasad, Bhagavatula, L. V.1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/nickel-catalyzed-direct-synthesis-dialkoxymethane-ethers01378nas a2200301 4500008004100000022001400041245008300055210006900138260000800207300001500215490000700230520045900237653001500696653002400711653001300735653002000748653001200768653001800780653001200798653001600810653001600826653003000842100002200872700002000894700002600914700002500940856011100965 2017 eng d a1477-052000aNickel-catalyzed N-vinylation of heteroaromatic amines via C-H bond activation0 aNickelcatalyzed Nvinylation of heteroaromatic amines via CH bond cSEP a 6896-69000 v153 a

Here, we report a ligand- and reductant-free nickel-catalyzed N-vinylation of heteroaromatic amines using biorenewable p-cymene as a solvent. This unprecedented cross-coupling strategy has high functional group tolerance (halides, alkoxy, cyano, chiral motif, etc.) and proceeded via C-H bond activation.

10aAlkylation10aAmination Reactions10aAnilines10aAryl Chlorides10ahalides10aMonoarylation10aO Bonds10aPrecatalyst10aPyrimidines10aRemoveble Directing Group1 aLandge, Vinod, G.1 aRana, Jagannath1 aSubaramanian, Murugan1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/nickel-catalyzed-n-vinylation-heteroaromatic-amines-c-h-bond-activation01063nas a2200169 4500008004100000245007600041210006900117260000800186300001600194490000700210520048200217100002100699700002000720700002000740700002500760856010800785 2017 eng d00aOrgano-photoredox catalyzed oxidative dehydrogenation of N-heterocycles0 aOrganophotoredox catalyzed oxidative dehydrogenation of Nheteroc cOCT a14167-141720 v233 aWe report here for the first time the catalytic oxidative dehydrogenation of N-heterocycles by a visible-light organo-photoredox catalyst with low catalyst loading (0.1-1mol%). The reaction proceeds efficiently under base- and additive-free conditions with ambient air at room temperature. The utility of this benign approach is demonstrated by the synthesis of various pharmaceutically relevant N-heteroarenes such as quinoline, quinoxaline, quinazoline, acridine, and indole.1 aSahoo, Manoj, K.1 aJaiswal, Garima1 aRana, Jagannath1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/organo-photoredox-catalyzed-oxidative-dehydrogenation-n-heterocycles02009nas a2200217 4500008004100000245017300041210006900214260000800283300001600291490000600307520117200313100002101485700002801506700001701534700002001551700002401571700002101595700002501616700002001641856013001661 2017 eng d00aPredesigned metal-anchored building block for in situ generation of Pd nanoparticles in porous covalent organic framework: application in heterogeneous tandem catalysis0 aPredesigned metalanchored building block for in situ generation  cAPR a13785-137920 v93 aThe development of nanoparticle-polymer-hybrid-based heterogeneous catalysts with high reactivity and good recyclability is highly desired for their applications in the chemical and pharmaceutical industries: Herein, we have developed a novel synthetic strategy by choosing a predesigned metal-anchored building block for in situ generation of metal (Pd) nanoparticles in the stable, porous, and crystalline covalent organic framework (COF), without using conventional reducing agents. In situ generation of Pd nanoparticles in the COF Skeleton is explicitly confirmed' from PXRD, XPS, TEM images, and N-15 NMR spectral analysis. This hybrid material is found to be an excellent reusable heterogeneous catalyst for the synthesis of biologically and pharmaceutically important 2-substituted benzofurans from 2-bromophencils and terminal alkynes via a tandem process with the turnover number up to 1101. The heterogeneity of the catalytic process is unambiguously verified by a mercury poisoning experiment and leaching test. This hybrid material shows superior catalytic performance compared to commercially available homogeneous as well as heterogeneous Pd catalysts.1 aBhadra, Mohitosh1 aSasmal, Himadri, Sekhar1 aBasu, Arghya1 aMidya, Siba, P.1 aKandambeth, Sharath1 aPachfule, Pradip1 aBalaraman, Ekambaram1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/predesigned-metal-anchored-building-block-situ-generation-pd-nanoparticles-porous-covalent01207nas a2200169 4500008004100000245015300041210006900194260000800263300001400271490000600285520052300291100002100814700002000835700002600855700002500881856013100906 2017 eng d00aRoom-temperature direct arylation of anilides under external oxidant-free conditions using CO2-Derived Dimethyl Carbonate (DMC) as a 'green' solvent0 aRoomtemperature direct arylation of anilides under external oxid cAUG a7565-75690 v23 a

Here, an efficient catalytic protocol for direct C-H bond arylation of anilides under base- and external oxidant-free conditions is reported. This reaction proceeds readily at room temperature using CO2-derived dimethyl carbonate (DMC) as a green solvent under visible-light dual catalysis. Later, application of our strategy for the gram-scale synthesis of Boscalid has been successfully shown. An unprecedented unsymmetrical bis-arylation of anilides is also demonstrated under mild, redox-neutral conditions.

1 aSahoo, Manoj, K.1 aRana, Jagannath1 aSubaramanian, Murugan1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/room-temperature-direct-arylation-anilides-under-external-oxidant-free-conditions-using-co201537nas a2200361 4500008004100000022001400041245007800055210006900133260000800202300001400210490000700224520045500231653002800686653001300714653001400727653001100741653001300752653002000765653002100785653003900806653002400845653002600869653001200895653001700907653001900924653002300943653002500966100002000991700001801011700001801029700002501047856010301072 2017 eng d a0039-788100aSimple cobalt(II) chloride catalyzed N-alkylation of amines with alcohols0 aSimple cobaltII chloride catalyzed Nalkylation of amines with al cSEP a3957-39610 v493 a

A facile cobalt-catalyzed N-alkylation of amines with alcohols using inexpensive, commercially available CoCl2 center dot 6H(2)O is reported. Employing this readily available cobalt catalyst, a variety of amines with wide functional group tolerance were selectively alkylated under benign conditions.

10a(Hetero)Aromatic Amines10aAlcohols10aAmination10aamines10aAnilines10aAromatic-amines10aCobalt Catalysis10aDehydrogenation Borrowing Hydrogen10aEfficient Catalysts10aHydrogen Autotransfer10aIridium10aN-alkylation10aPincer-complex10aSecondary Alcohols10aSelective Alkylation1 aMidya, Siba, P.1 aMondal, Akash1 aBegum, Ayesha1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/simple-cobaltii-chloride-catalyzed-n-alkylation-amines-alcohols01321nas a2200181 4500008004100000022001400041245008800055210006900143260000900212300001400221490000700235520069700242100002100939700002000960700002200980700002501002856011201027 2017 eng d a1463-926200aUnified strategy for silver-, base-, and oxidant-free direct arylation of C-H bonds0 aUnified strategy for silver base and oxidantfree direct arylatio cMAY  a2111-21170 v193 a

Here, we report a dual catalytic approach for room temperature direct arylation of C-H bonds with aryldiazonium salts as a simple aryl group donor, also working as an internal oxidant via C-N-2 bond cleavage. This unified strategy has been achieved by the synergistic combination of visible-light metal-free photoredox and palladium catalysis under silver-, base-and/or additive-free conditions. The broad substrate scope, functional group tolerance, excellent regioselectivity and redox-neutral conditions of this process make it attractive for the effective synthesis of a wide range of important N-heterocyclic commodities such as dibenzo [b,d]azepine, carbazole and phenanthridine.

1 aSahoo, Manoj, K.1 aMidya, Siba, P.1 aLandge, Vinod, G.1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/unified-strategy-silver-base-and-oxidant-free-direct-arylation-c-h-bonds00985nas a2200193 4500008004100000022001400041245015100055210006900206260000800275300001000283490000700293520025200300100002000552700002200572700002100594700002000615700002500635856013100660 2018 eng d a1359-734500aCobalt-catalyzed acceptorless dehydrogenative coupling of aminoalcohols with alcohols: direct access to pyrrole, pyridine and pyrazine derivatives0 aCobaltcatalyzed acceptorless dehydrogenative coupling of aminoal cJAN a90-930 v543 a

Here, the first example is reported of a new, molecularly defined SNS-cobalt(II) catalyst for the acceptorless dehydrogenative coupling (ADC) of unprotected amino alcohols with secondary alcohols leading to pyrrole and pyridine derivatives.

1 aMidya, Siba, P.1 aLandge, Vinod, G.1 aSahoo, Manoj, K.1 aRana, Jagannath1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/cobalt-catalyzed-acceptorless-dehydrogenative-coupling-aminoalcohols-alcohols-direct-access01048nas a2200193 4500008004100000022001400041245013800055210006900193260000800262300001400270490000600284520032000290100002000610700002700630700002200657700001900679700002500698856013100723 2018 eng d a2044-475300aDirect access to N-alkylated amines and imines via acceptorless dehydrogenative coupling catalyzed by a cobalt(ii)-NNN pincer complex0 aDirect access to Nalkylated amines and imines via acceptorless d cJUL a3469-34730 v83 a

A simple, phosphine-free Co(ii)-NNN pincer complex catalyzed direct N-alkylation of anilines with alcohols via hydrogen auto-transfer (HA) and selective acceptorless dehydrogenative coupling (ADC) of benzylamines with alcohols affording imines with the liberation of molecular hydrogen and water is reported.

1 aMidya, Siba, P.1 aPitchaimani, Jayaraman1 aLandge, Vinod, G.1 aMadhu, Vedichi1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/direct-access-n-alkylated-amines-and-imines-acceptorless-dehydrogenative-coupling-catalyzed01754nas a2200169 4500008004100000022001400041245018800055210006900243260000800312300001400320490000600334520103900340100002301379700002501402700002801427856012901455 2018 eng d a2044-475300aEfficient solar light-driven H-2 production: post-synthetic encapsulation of a Cu2O co-catalyst in a metal-organic framework (MOF) for boosting the effective charge carrier separation0 aEfficient solar lightdriven H2 production postsynthetic encapsul cJUL a3286-32940 v83 a

The development of new and efficient catalytic systems for solar light-driven hydrogen generation is one of the prime focuses of contemporary chemical sciences. Indeed, the charge carrier separation efficiency of a photocatalyst plays a vital role in photocatalysis. Herein, we have successfully designed a Cu2O-encapsulating NH2-MIL-125(Ti) MOF by a post-synthetic encapsulation strategy. The Cu2O-encapsulating MOF material showed a remarkable enhancement in photocatalytic H-2 production activity under solar light illumination. Gratifyingly, the H-2 production activity under solar light was around approximate to 28-fold higher than that of the pristine MOF. The enhancement in photocatalytic activity may be attributed to efficient charge carrier separation through Ti3+ sites and the broad light absorption of the Cu2O-encapsulating MOF photocatalyst. The possible electron transport mechanism, potential energy diagram (V vs. NHE), and the existence of Ti3+ ions have been demonstrated by various spectroscopic studies.

1 aKarthik, Peramaiah1 aBalaraman, Ekambaram1 aNeppolian, Bernaurdshaw uhttps://library.ncl.res.in/content/efficient-solar-light-driven-h-2-production-post-synthetic-encapsulation-cu2o-co-catalyst00939nas a2200193 4500008004100000022001400041245009100055210006900146260000800215300001400223490000700237520027300244100002200517700001800539700001700557700002900574700002500603856011700628 2018 eng d a1477-052000aManganese catalyzed N-alkylation of anilines with alcohols: ligand enabled selectivity0 aManganese catalyzed Nalkylation of anilines with alcohols ligand cNOV a8175-81800 v163 aLigand enabled Earth-abundant manganese catalyzed N-alkylation of amines with alcohols via a hydrogen auto-transfer strategy is reported. The choice of the ligand plays a significant role in the alcohol reactivity (aliphatic or aromatic) toward N-alkylation reactions.1 aLandge, Vinod, G.1 aMondal, Akash1 aKumar, Vinit1 aNandakumar, Avanashiappn1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/manganese-catalyzed-n-alkylation-anilines-alcohols-ligand-enabled-selectivity01486nas a2200193 4500008004100000245011800041210006900159260000800228300001400236490000700250520076300257100002001020700002001040700002701060700003001087700001901117700002501136856013101161 2018 eng d00a Ni-catalyzed alpha-alkylation of unactivated amides and esters with alcohols by hydrogen auto-transfer strategy 0 aNicatalyzed alphaalkylation of unactivated amides and esters wit cNOV a3911-39160 v113 aA transition-metal-catalyzed borrowing hydrogen/hydrogen auto-transfer strategy allows the utilization of feedstock alcohols as an alkylating partner, which avoids the formation of stoichiometric salt waste and enables a direct and benign approach for the construction of C-N and C-C bonds. In this study, a nickel-catalyzed alpha-alkylation of unactivated amides and ester (tert-butyl acetate) is carried out by using primary alcohols under mild conditions. This C-C bond-forming reaction is catalyzed by a new, molecularly defined nickel(II) NNN-pincer complex (0.1-1 mol %) and proceeds through hydrogen auto-transfer, thereby releasing water as the sole byproduct. In addition, N-alkylation of cyclic amides under Ni-catalytic conditions is demonstrated.1 aMidya, Siba, P.1 aRana, Jagannath1 aPitchaimani, Jayaraman1 aNandakumar, Avanashiappan1 aMadhu, Vedichi1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/ni-catalyzed-alpha-alkylation-unactivated-amides-and-esters-alcohols-hydrogen-auto-transfer01184nas a2200169 4500008004100000245010600041210006900147260000800216300001400224490000600238520056500244100002000809700001700829700002600846700002500872856011700897 2018 eng d00aNi-catalyzed dehydrogenative coupling of primary and secondary alcohols with methyl-N-heteroaromatics0 aNicatalyzed dehydrogenative coupling of primary and secondary al cNOV a3250-32550 v53 aHere we report the first base-metal catalyzed dehydrogenative coupling of primary (aromatic, heteroaromatic, and aliphatic) and secondary alcohols with methyl-N-heteroaromatics to form various C(sp(3))-alkylated N-heteroaromatics. The reaction is enabled by Earth abundant, non-precious NiBr2 as a transition metal catalyst and N,N,N,N-tetramethylethylenediamine (TMEDA) as a ligand system. Mechanistic studies reveal that a hydrogen auto-transfer process is involved in the direct C(sp(3))-alkylation and the reaction proceeds through an -olefination process.1 aRana, Jagannath1 aBabu, Reshma1 aSubaramanian, Murugan1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/ni-catalyzed-dehydrogenative-coupling-primary-and-secondary-alcohols-methyl-n01243nas a2200181 4500008004100000022001400041245012700055210006900182260000800251300001400259490000700273520055300280100002200833700002000855700003000875700002500905856013100930 2018 eng d a1359-734500aPd(II)-Catalyzed gamma-C(sp(3))-H alkynylation of amides: selective functionalization of R chains of amides (RC)-C-1(O)NHR0 aPdIICatalyzed gammaCsp3H alkynylation of amides selective functi cJUL a7483-74860 v543 a

The gamma C(sp(3))-H bond alkynylation of R chains of amides (RC)-C-1(O)NHR, a fundamental class of synthetic substrates, has not been accomplished to date. Here, the first example of palladium(ii)-catalyzed alkynylation of an unactivated gamma C(sp(3))-H bond of alkyl amides (cyclic, linear, and amino acids) is reported. The kinetic experiment shows that the rate of the reaction depends on the coupling partners and the amides. Late-stage diversification of alkynylated amides was developed by utilizing amine and alkyne functionalities.

1 aLandge, Vinod, G.1 aParveen, Ayisha1 aNandakumar, Avanashiappan1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/pdii-catalyzed-gamma-csp3-h-alkynylation-amides-selective-functionalization-r-chains-amides01174nas a2200205 4500008004100000022001400041245010200055210006900157260000800226300001200234490000600246520045100252100002200703700002700725700002000752700002600772700001900798700002500817856012600842 2018 eng d a2044-475300aPhosphine-free cobalt pincer complex catalyzed Z-selective semi-hydrogenation of unbiased alkynes0 aPhosphinefree cobalt pincer complex catalyzed Zselective semihyd cJAN a428-4330 v83 a

Herein, we report a novel, molecularly defined NNN-type cobalt pincer complex catalyzed transfer semi-hydrogenation of unbiased alkynes to Z-selective alkenes. This unified process is highly stereo-and chemo-selective and exhibits a broad scope as well as wide functional group tolerance. Ammonia-borane (AB), a bench-stable substrate with high gravimetric hydrogen capacity, was used as a safe and practical transfer hydrogenating source.

1 aLandge, Vinod, G.1 aPitchaimani, Jayaraman1 aMidya, Siba, P.1 aSubaramanian, Murugan1 aMadhu, Vedichi1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/phosphine-free-cobalt-pincer-complex-catalyzed-z-selective-semi-hydrogenation-unbiased01928nas a2200241 4500008004100000022001400041245009800055210006900153260000800222300001400230490000600244520110600250653003301356653001601389653001901405653001301424653002501437100002101462700003101483700002001514700002501534856012701559 2018 eng d a2155-543500aPhotocatalysis enabling acceptorless dehydrogenation of diaryl hydrazines at room temperature0 aPhotocatalysis enabling acceptorless dehydrogenation of diaryl h cAUG a7727-77330 v83 a

Aromatic azo compounds are privileged structural motifs, and they exhibit a myriad of pharmaceutical as well as industrial applications. Here, we report a catalytic acceptorless dehydrogenation of diarylhydrazine derivatives to access a wide variety of aryl-azo compounds with the removal of molecular hydrogen as the sole byproduct. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)(3)](2+) as the photoredox catalyst and Co(dmgH)(2)(py)Cl as the proton-reduction catalyst. The reaction proceeds smoothly under very mild and benign conditions and operates at ambient temperature. This dual catalytic approach is highly compatible with many different functional groups and has a broad substrate scope. We have also demonstrated the reversible hydrogen storage and release phenomenon on hydrazobenzene/azobenzene couple to show the utility of these compounds as hydrogen storage materials. Further diversification of azobenzene was shown by a transition metal-catalyzed azo-group-directed ortho-C-H bond functionalization.

10aacceptorless dehydrogenation10aAzo benzene10adual catalysis10aHydrogen10aphotoredox catalysis1 aSahoo, Manoj, K.1 aSaravanakumar, Krishnasamy1 aJaiswal, Garima1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/photocatalysis-enabling-acceptorless-dehydrogenation-diaryl-hydrazines-room-temperature00982nas a2200169 4500008004100000022001400041245011900055210006900174260000900243300001400252490000700266520034400273100002000617700002500637700002500662856012500687 2019 eng d a1477-922600aManganese-catalyzed direct C-C coupling of -C-H bonds of amides and esters with alcohols via hydrogen autotransfer0 aManganesecatalyzed direct CC coupling of CH bonds of amides and  cJUN  a7094-70990 v483 a

Herein we report an efficient manganese-catalyzed C-alkylation of unactivated amides and tert-butyl acetate using alcohols as alkylating agents. This elegant approach exhibits a broad substrate scope providing the C-C coupled products of amides via a hydrogen auto-transfer strategy using aryl, heteroaryl, and aliphatic alcohols.

1 aRana, Jagannath1 aGupta, Virendrakumar1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/manganese-catalyzed-direct-c-c-coupling-c-h-bonds-amides-and-esters-alcohols-hydrogen01787nas a2200205 4500008004100000022001400041245008100055210006900136260000800205300001600213490000600229520106100235100002801296700002201324700003301346700003501379700002501414700003601439856010601475 2019 eng d a2470-134300aMolecular cobalt(II) complexes for tau polymerization in Alzheimer's disease0 aMolecular cobaltII complexes for tau polymerization in Alzheimer cOCT a16702-167140 v43 a

Tau is an axonal protein known to form abnormal aggregates and is the biomarker of Alzheimer's disease. Metal-based therapeutics for inhibition of Tau aggregation is limited and rarely reported in contemporary science. Here, we report the first example of rationally designed molecular cobalt(II)-complexes for effective inhibition of Tau and disaggregation of preformed Tau fibrils. The mechanistic studies reveal that prevention of Tau aggregation by cobalt-based metal complexes (CBMCs) is concentration-dependent and Tau seldom exhibits conformational changes. Interestingly, CBMCs play dual role in causing disassembly of preformed aggregates as well as inhibition of complete Tau aggregation. Furthermore, CBMCs were nontoxic and maintained the tubulin network intact. CBMCs also prevented okadaic acid-induced toxicity in SH-SY5Y cells thus, preventing hyperphosphorylation of Tau. We believe that this unprecedented finding by the newly developed molecular complexes has a potential toward metal-based therapeutics for Alzheimer's disease.

1 aGorantla, Nalini, Vijay1 aLandge, Vinod, G.1 aNagaraju, Pramod, Gudigenaha1 aPriyadarshini, Poornima, C. G.1 aBalaraman, Ekambaram1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/molecular-cobaltii-complexes-tau-polymerization-alzheimers-disease00865nas a2200193 4500008004100000022001400041245010400055210006900159260000900228300001400237490000700251520018500258100002200443700001800465700002600483700002000509700002500529856011700554 2019 eng d a1359-734500aNickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones with the liberation of H-20 aNickeliicatalyzed direct olefination of benzyl alcohols with sul cMAY  a6130-61330 v553 a

A nickel(II)-catalyzed direct olefination of benzyl alcohols with sulfones to access various terminal and internal olefins with the liberation of hydrogen gas is reported.

1 aLandge, Vinod, G.1 aYadav, Vinita1 aSubaramanian, Murugan1 aDangarh, Pragya1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/nickelii-catalyzed-direct-olefination-benzyl-alcohols-sulfones-liberation-h-201362nas a2200169 4500008004100000245010900041210006900150260000800219300001400227490000700241520072800248100002000976700002600996700002101022700002501043856012401068 2019 eng d00aReusable cobalt catalyst for reversible acceptorless dehydrogenation and hydrogenation of N-Heterocycles0 aReusable cobalt catalyst for reversible acceptorless dehydrogena cMAY a2449-24570 v113 a

The development of robust catalytic systems based on basemetals for reversible acceptorless dehydrogenation (ADH) and hydrogenation of feedstock chemicals is very important in the context of ` hydrogen storage'. Herein, we report a highly efficient reusable cobalt-based heterogeneous catalyst for reversible dehydrogenation and hydrogenation of N-heterocycles. Both the ADH and the hydrogenation processes operate under mild, benign conditions.

1 aJaiswal, Garima1 aSubaramanian, Murugan1 aSahoo, Manoj, K.1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/reusable-cobalt-catalyst-reversible-acceptorless-dehydrogenation-and-hydrogenation-n01316nas a2200157 4500008004100000022001400041245011600055210006900171260000900240300001400249490000700263520071100270100002100981700002501002856013101027 2019 eng d a1463-926200aRoom temperature catalytic dehydrogenation of cyclic amines with the liberation of H-2 using water as a solvent0 aRoom temperature catalytic dehydrogenation of cyclic amines with cAPR  a2119-21280 v213 a

Catalytic dehydrogenation of cyclic amines, in particular partially saturated N-heterocycles to N-heterocyclic arenes, with the removal of molecular hydrogen as the sole byproduct in water is reported. This dehydrogenation reaction proceeds smoothly under very mild and benign conditions and operates at room temperature. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)(3)](2+) as the photoredox catalyst and a newly synthesized cobalt complex as the proton-reduction catalyst. A detailed mechanistic study (control experiments, electrochemical studies, UV-visible experiments) is presented for the present dual catalysis.

1 aSahoo, Manoj, K.1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/room-temperature-catalytic-dehydrogenation-cyclic-amines-liberation-h-2-using-water-solvent01493nas a2200205 4500008004100000022001400041245011700055210006900172260000900241300001400250490000800264520075900272100002101031700002401052700002101076700002201097700002501119700002001144856012301164 2019 eng d a0002-786300aTriazine functionalized porous covalent organic framework for photo-organocatalytic E-Z isomerization of olefins0 aTriazine functionalized porous covalent organic framework for ph cAPR  a6152-61560 v1413 a

Visible light-mediated photocatalytic organic transformation has drawn significant attention as an alternative process for replacing thermal reactions. Although precious metal/organic dyes based homogeneous photocatalysts have been developed, their toxic and nonreusable nature makes them inappropriate for large-scale production. Therefore, we have synthesized a triazine and a keto functionalized nonmetal based covalent organic framework (TpTt) for heterogeneous photo catalysis. As the catalyst shows significant absorption of visible light, it has been applied for the photocatalytic uphill conversion of trans-stilbene to cis-stilbene in the presence of blue light-emitting diodes with broad substrate scope via an energy transfer process.

1 aBhadra, Mohitosh1 aKandambeth, Sharath1 aSahoo, Manoj, K.1 aAddicoat, Matthew1 aBalaraman, Ekambaram1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/triazine-functionalized-porous-covalent-organic-framework-photo-organocatalytic-e-z02051nas a2200229 4500008004100000022001400041245009500055210006900150260000900219300001200228490000800240520126000248653002401508653002401532653002001556653001901576653001701595100002101612700002501633700003601658856012701694 2020 eng d a0141-813000aCobalt-based metal complexes prevent repeat tau aggregation and nontoxic to neuronal cells0 aCobaltbased metal complexes prevent repeat tau aggregation and n cJUN  a171-1790 v1523 a

Alzheimer's disease (AD) is a fatal neurodegenerative disorder with an alarming increase in the death rate every year. AD is characterised by an aberrant accumulation of proteins in the form of aggregates. The axonal microtubule-associated protein Tau and arnyloid-beta undergo structural transition to beta-sheet rich structure and form aggregates in neuronal soma as well as in the extracellular region. The loss of Tau from microtubules leads to the disintegration of axon and causing neuronal degeneration. This led to the development of effective drugs against AD, to prevent Tau aggregation. Here, we synthesized and screen metal-based complexes to prevent Tau protein aggregation. ThS fluorescence and TEM suggested the role of synthetic cobalt complexes in inhibiting Tau aggregation. CD spectroscopy showed that these complexes prevented conformational changes in Tau to beta-sheet. CBMCs were not toxic at lower concentrations and formed non-toxic Tau species. L1 and L2 prevented membrane leakage: whereas, higher concentrations of L3 caused membrane leakage as observed by LDH release assay. The overall results indicate the synthetic cobalt complexes to be a promising molecule against AD. (C) 2020 Elsevier B.V. All rights reserved.

10aAlzheimer's disease10aCobalt-based metals10aTau Aggregation10aTau inhibition10aTau toxicity1 aGorantla, Nalini1 aBalaraman, Ekambaram1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/cobalt-based-metal-complexes-prevent-repeat-tau-aggregation-and-nontoxic-neuronal-cells01330nas a2200205 4500008004100000022001400041245006100055210005900116260000900175300001400184490000700198520069300205100002200898700001700920700001800937700002600955700002500981700002501006856009301031 2020 eng d a0022-326300aIron-catalyzed direct julia-type olefination of alcohols0 aIroncatalyzed direct juliatype olefination of alcohols cAUG  a9876-98860 v853 a

Herein, we report an iron-catalyzed, convenient, and expedient strategy for the synthesis of styrene and naphthalene derivatives with the liberation of dihydrogen. The use of a catalyst derived from an earth-abundant metal provides a sustainable strategy to olefins. This method exhibits wide substrate scope (primary and secondary alcohols) functional group tolerance amino, nitro, halo, alkoxy, thiomethoxy, and S- and N-heterocyclic compounds) that can be scaled up. The unprecedented synthesis of 1-methyl naphthalenes proceeds via tandem methenylation/double dehydrogenation. Mechanistic study shows that the cleavage of the C-H bond of alcohol is the rate-determining step.

1 aLandge, Vinod, G.1 aBabu, Reshma1 aYadav, Vinita1 aSubaramanian, Murugan1 aGupta, Virendrakumar1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/iron-catalyzed-direct-julia-type-olefination-alcohols01530nas a2200241 4500008004100000022001400041245007800055210006900133260000800202300001200210490000700222520076900229653003300998653001201031653002201043653001301065653001401078100001801092700002201110700002601132700002501158856010501183 2020 eng d a2155-543500aManganese-catalyzed alpha-olefination of nitriles with secondary alcohols0 aManganesecatalyzed alphaolefination of nitriles with secondary a cJAN a947-9540 v103 a

An expedient catalytic approach for alpha-olefination of nitriles using secondary alcohols with the liberation of molecular hydrogen and water as the only byproducts is reported. This reaction is catalyzed by a molecularly defined manganese(I) pincer complex and operates in the absence of any hydrogen acceptors. A broad range of substrates including cyclic, acyclic, and benzylic alcohols, as well as various nitrile derivatives, such as arylmethyl and heteroarylmethyl nitriles, are employed in the reaction to provide a diverse range of alpha-vinyl nitriles in good to excellent yields. Mechanistic studies showed that the reaction proceeds via dehydrogenative pathway and the activation of alpha(C-H) bond of the alcohol is the rate-determining step.

10aacceptorless dehydrogenation10aAlcohol10aalpha-olefination10aHydrogen10amanganese1 aYadav, Vinita1 aLandge, Vinod, G.1 aSubaramanian, Murugan1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/manganese-catalyzed-alpha-olefination-nitriles-secondary-alcohols01956nas a2200253 4500008004100000022001400041245007600055210006900131260000900200300001400209490000800223520116500231653001601396653002401412653001101436653001501447653002001462653000801482100002801490700001601518700002501534700003601559856010701595 2020 eng d a0141-813000aTransition metal nickel prevents Tau aggregation in Alzheimer's disease0 aTransition metal nickel prevents Tau aggregation in Alzheimers d cAUG  a1359-13650 v1563 a

Alzheimer's disease is the leading cause of dementia, effecting majority of aged people worldwide. The multifaceted effectors of Alzheimer's disease primarily include Tau, amyloid-beta along with hyper activation of kinases, oxidative stress and mutations etc., makes it challenging to design therapeutics. Tau is a microtubule-associating protein, which is subjected to cellular stress resulting in the formation of neurofibrillary tangles, leading to loss of affinity for microtubules. This causes loss of microtubule stability and in turn alters axonal integrity. In the present work, emphasis towards understanding interaction of nickel with Tau was made. Metals such as iron, zinc, copper and lead etc., are known to modulate Tau conformation and enhance its aggregation. Our results showed the deliverance of Tau aggregation by nickel and its synthetic morpholine conjugate. Nickel prevents aggregation by inducing degradation of Tau as evidenced by SDS-PAGE and TEM. Nickel and the synthetic conjugate being non toxic to neuro2a cells and prevent Tau aggregation, might direct these complexes to overcome AD. (C) 2019 Published by Elsevier B.V.

10aAggregation10aAlzheimer's disease10ametals10aMorpholine10aNickel chloride10aTau1 aGorantla, Nalini, Vijay1 aDas, Rashmi1 aBalaraman, Ekambaram1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/transition-metal-nickel-prevents-tau-aggregation-alzheimers-disease01170nas a2200181 4500008004100000022001400041245007300055210006900128260000800197490000700205520056700212100002100779700002300800700001900823700001900842700002500861856010200886 2021 eng d a1477-052000aConvenient semihydrogenation of azoarenes to hydrazoarenes using H-20 aConvenient semihydrogenation of azoarenes to hydrazoarenes using cJUN0 v193 a

The high atom-economical and eco-benign nature of hydrogenation reactions make them much more superior to conventional reduction and transfer hydrogenation. Herein, a convenient and highly selective hydrogenation reaction of azoarenes using molecular hydrogen to access diverse hydrazoarenes is reported. The present catalytic method is general and operationally simple, and it operates under exceedingly mild conditions (room temperature and 1 atm of hydrogen pressure). The reusability of catalysts used in this method is also successfully demonstrated.

1 aSahoo, Manoj, K.1 aSivakumar, Ganesan1 aJadhav, Sanjay1 aShaikh, Samrin1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/convenient-semihydrogenation-azoarenes-hydrazoarenes-using-h-202146nas a2200289 4500008004100000022001400041245013400055210006900189260000900258300001200267490000700279520117400286653000801460653001101468653003001479653002301509653002801532100001501560700001901575700002101594700002601615700002501641700002701666700001701693700002301710856012301733 2021 eng d a1867-388000aInsights into the nature of self-extinguishing external donors for ziegler-natta catalysis: a combined experimental and DFT study0 aInsights into the nature of selfextinguishing external donors fo cJAN  a674-6810 v133 a

Developing donors for Ziegler-Natta (ZN) catalysis to control the polymerization reaction and produce polymers with desirable properties has always been challenging due to the multi-component nature of the catalytic systems. Here, we have developed a new synthetic protocol for making two external donors, D-1 (2,2,2-trifluoroethyl myristate) and D-2 (2,2,2-trifluoroethyl palmitate) that show self-extinguishing properties, followed by a systematic DFT study to understand this peculiar property of these donors. D-1 and D-2 can undergo parallel reactions with aluminum and titanium species present in the system to produce ketones and aldehydes, which are poisons for ZN catalytic systems, thus explaining their self-extinguishing nature. The non-covalent interaction between the long alkyl chain of the donors with the surface plays a vital role in determining the donors ` self-extinguishing nature. There is a significant thermodynamic preference for the binding of the donor with the longer alkyl chain at the titanium center. The current work, therefore, provides interesting insights into how self-extinguishing donors function in ZN catalytic systems.

10aDFT10adonors10anon-covalent interactions10aself-extinguishing10aZiegler-Natta catalysis1 aRaj, Vipin1 aKumawat, Jugal1 aDhamaniya, Sunil1 aSubaramanian, Murugan1 aBalaraman, Ekambaram1 aGupta, Virendra, Kumar1 aVanka, Kumar1 aGrubbs, Robert, H. uhttps://library.ncl.res.in/content/insights-nature-self-extinguishing-external-donors-ziegler-natta-catalysis-combined01315nas a2200229 4500008004100000022001400041245011300055210006900168260000900237300001400246490000800260520053100268653003300799653001200832653001100844653001400855653001900869100001800888700002500906700002400931856013000955 2021 eng d a1615-415000aPhosphine-free manganese(II)-catalyst enables acceptorless dehydrogenative coupling of alcohols with indoles0 aPhosphinefree manganeseIIcatalyst enables acceptorless dehydroge cSEP  a4430-44390 v3633 aHerein, an air-stable, molecularly defined NNN-Mn(II) pincer complex catalyzed acceptorless dehydrogenative coupling of alcohols with indoles is reported. A wide variety of symmetrical and unsymmetrical bis(indolyl)methane derivatives as well as some structurally important products such as Vibrindole A, Turbomycin B alkaloid, Antileukemic, and Anticancer agents were synthesized. Mechanistic studies illustrate the importance of the NH moiety in the complex and the crucial role of metal-ligand cooperation during catalysis.10aacceptorless dehydrogenation10aAlcohol10aIndole10amanganese10aphosphine-free1 aYadav, Vinita1 aBalaraman, Ekambaram1 aMhaske, Santosh, B. uhttps://library.ncl.res.in/content/phosphine-free-manganeseii-catalyst-enables-acceptorless-dehydrogenative-coupling-alcohols02732nas a2200169 4500008004100000245009100041210006900132260000800201300001600209490000700225520219400232100001802426700002302444700002502467700002502492856004502517 2021 eng d00aRecent advances in liquid organic hydrogen carriers: an alcohol-based hydrogen economy0 aRecent advances in liquid organic hydrogen carriers an alcoholba cNOV a14712-147260 v113 aEnergy storage and the use of abundantly available feedstock without contributing to the carbon footprint are two significant global challenges. In this regard, the development of high-performance, low-cost, sustainable, and environmentally friendly energy storage and production systems is crucial to fulfill the growing energy demands of the current society. The use of hydrogen will diversify energy sources as it significantly reduces greenhouse gas emissions and environmental pollution during energy conversion. Although the hydrogen economy is quite beneficial, hydrogen storage is still very challenging, and the existing methods suffer from a lot of problems and drawbacks. The conventional liquefaction and compression hydrogen storage technologies are associated with several challenges, including low storage density, boil-off losses, relatively high costs, and safety and transportation concerns. In recent years, liquid organic hydrogen carrier (LOHC) systems have attained a lot of importance as a substitute for the traditional storage methods. Hydrogen storage and transport using LOHCs are based on two-step cycles, such as (i) loading/storage of hydrogen by catalytic hydrogenation of H2-lean compounds and (ii) unloading/releasing hydrogen by dehydrogenating the resulting H2-rich liquids. Since alcohols are widely accessible from various industrial processes or even from biomass-derived precursors, the catalytic acceptorless dehydrogenation of alcohols is an attractive approach for future hydrogen storage applications. Hence, the catalytic dehydrogenation-hydrogenation of alcohols can be used for the development of alcohol-based LOHC systems which are economical, safe, and easy to handle. Further, they are similar to crude oils under ambient conditions and thus are suitable for use in the current energy infrastructure. This Review covers several essential aspects of these developing efficient and abundantly available LOHC systems for efficient hydrogen storage and transport applications. Additionally, reversible LOHC systems based on the catalytic dehydrogenation-hydrogenation of alcohols and their corresponding carbonyl compounds have been discussed.1 aYadav, Vinita1 aSivakumar, Ganesan1 aGupta, Virendrakumar1 aBalaraman, Ekambaram uhttps://doi.org/10.1021/acscatal.1c0328301432nas a2200193 4500008004100000022001400041245008400055210006900139260000800208300001400216490000700230520077600237100002001013700002601033700001701059700001801076700002501094856011901119 2021 eng d a0022-326300aTandem acceptorless dehydrogenative coupling-decyanation under nickel catalysis0 aTandem acceptorless dehydrogenative couplingdecyanation under ni cJUN a7552-75620 v863 aThe development of new catalytic processes based on abundantly available starting materials by cheap metals is always a fascinating task and marks an important transition in the chemical industry. Herein, a nickel-catalyzed acceptorless dehydrogenative coupling of alcohols with nitriles followed by decyanation of nitriles to access diversely substituted olefins is reported. This unprecedented C=C bond-forming methodology takes place in a tandem manner with the formation of formamide as a sole byproduct. The significant advantages of this strategy are the low-cost nickel catalyst, good functional group compatibility (ether, thioether, halo, cyano, ester, amino, N/O/S heterocycles; 43 examples), synthetic convenience, and high reaction selectivity and efficiency.1 aMidya, Siba, P.1 aSubaramanian, Murugan1 aBabu, Reshma1 aYadav, Vinita1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/tandem-acceptorless-dehydrogenative-coupling-decyanation-under-nickel-catalysis01505nas a2200181 4500008004100000022001400041245009600055210006900151260000800220300001400228490000700242520086100249100001801110700002301128700002501151700002401176856012301200 2022 eng d a1523-706000aNickel-catalyzed direct synthesis of N-substituted indoles from amino alcohols and alcohols0 aNickelcatalyzed direct synthesis of Nsubstituted indoles from am cDEC a9054-90590 v243 a

A one-pot cascade approach for the synthesis of N substituted indoles from amino alcohols and alcohols under additive and base-free conditions with the liberation of water as the only stoichiometric byproduct is reported. The commercially available bench-stable Ni(OTf)2 salt in combination with 1,2-bis(dicyclohexylphosphino)ethane (dcype) is very effective for this unprecedented catalytic transformation. A broad range of substrates including aromatic and aliphatic primary alcohols, cyclic and acyclic secondary alcohols, and various substituted 2-aminophenyl ethyl alcohols are employed in the reaction conditions to provide a diverse range of N-alkylated indoles. Mechanistic studies revealed that the reaction proceeds through tandem N-alkylation via hydrogen autotransfer followed by the cyclization of N-alkylated alcohol intermediate.

1 aYadav, Vinita1 aJagtap, Sayali, G.1 aBalaraman, Ekambaram1 aMhaske, Santosh, B. uhttps://library.ncl.res.in/content/nickel-catalyzed-direct-synthesis-n-substituted-indoles-amino-alcohols-and-alcohols02102nas a2200289 4500008004100000022001400041245013100055210006900186260000800255300001400263490000700277520110200284653001301386653003201399653002901431653002101460653002101481653001901502100002601521700002301547700002501570700002301595700002501618700001701643700002501660856012701685 2024 eng d a2155-543500aDehydrogenative coupling of alcohols with internal alkynes under nickel catalysis: an access to β-deuterated branched ketones0 aDehydrogenative coupling of alcohols with internal alkynes under cMAY a8294-83090 v143 a

In synthetic organic chemistry, unconventional strategies for advanced chemical synthesis pose interesting and challenging problems. Alcohols act as alkylating agents in the C-C and C-N bond-forming reactions via the dehydrogenative borrowing hydrogen strategy in traditional transition metal catalysis; however, as an acylating agent in the C-C bond-forming reactions is challenging and rarely reported. Here, we report the dehydrogenative coupling of benzylic alcohols with internal alkynes under nickel(II) catalysis, wherein alcohol is used as an acylating agent. This reaction system affords a wide range of alpha-branched aryl ketone derivatives with zero waste generation through the umpolung borrowing hydrogen strategy. Moreover, we have demonstrated the chemodivergent applications of the alpha-disubstituted ketones to other valuable building blocks, including large-scale synthesis of beta-deuterated branched ketones. Several spectroscopic studies, intermediate identification, and density functional theory calculations were performed to elucidate the reaction mechanism.

10aAlcohols10aalpha-branched aryl ketones10adehydrogenative coupling10ainternal alkynes10anickel catalysis10apseudoumpolung1 aSubaramanian, Murugan1 aGouda, Chandrakant1 aRoy, Triptesh, Kumar1 aGanesan, Sivakumar1 aBanerjee, Subhrashis1 aVanka, Kumar1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/dehydrogenative-coupling-alcohols-internal-alkynes-under-nickel-catalysis-access-%CE%B201989nas a2200205 4500008004100000022001400041245017100055210006900226260000800295300001400303490000700317520119400324100002601518700002801544700002401572700001501596700001701611700002501628856013001653 2024 eng d a2044-475300aNickel-catalyzed tandem conversion of paraformaldehyde : methanol to hydrogen and formate/chemo- and stereoselective hydrogenation of alkynes under neutral conditions0 aNickelcatalyzed tandem conversion of paraformaldehyde methanol t cMAY a2779-27930 v143 a

The development of new catalytic protocols for clean and COx-free hydrogen generation from fundamental feedstocks is always interesting and challenging. Herein, we disclose nickel-catalyzed dihydrogen generation from a mixture of paraformaldehyde-methanol under base-free and activator-free conditions. The dihydrogen generation from this redox combination under neutral, oxidative coupling conditions has been integrated with the hydrogen transfer reactions such as chemo- and stereoselective hydrogenation of alkynes in a tandem manner. This unprecedented strategy provides diverse highly stereoselective olefins with excellent tolerance of reducible functional groups such as ether, silyl ether, aldehyde, keto, ester, nitrile, halides including bromo and iodo groups, and heteroarenes. Additionally, we demonstrated catalytic stereo-interconversion of alkenes under benign conditions. The affordable gram-scale synthesis of some important pharmaceutical bioactive molecules has further enhanced their synthetic value. A tandem dihydrogen generation from a mixture of paraformaldehyde-methanol under base-free conditions followed by semihydrogenation of alkynes is reported.

1 aSubaramanian, Murugan1 aPadhy, Subarna, Sukanya1 aGouda, Chandrakanth1 aDas, Tamal1 aVanka, Kumar1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/nickel-catalyzed-tandem-conversion-paraformaldehyde-methanol-hydrogen-and-formatechemo-and