01868nas a2200241 4500008004100000022001400041245012500055210006900180260009900249300001000348490000800358520098600366653001801352653000801370653001301378653001401391653001201405653001301417100002301430700001701453700002701470856012901497 2012 eng d a0008-621500aRadical mediated deoxygenation of inositol benzylidene acetals: conformational analysis, DFT calculations, and mechanism0 aRadical mediated deoxygenation of inositol benzylidene acetals c aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcAPR a26-340 v3513 a

Xanthates of 1,3-benzylidene acetal derivatives of myo- and neo-inositols undergo dideoxygenation under Barton-McCombie conditions, as a result of intramolecular abstraction of the benzylidene acetal hydrogen and subsequent cleavage of the acetal ring. Scrutiny of structure of these bicyclic inositol derivatives shows that although the conformation of the two rings can vary depending on the configuration of the inositol ring and the phase in which the molecules are present, both the xanthates lead to the formation of the same dideoxyinositol. DFT calculations on these molecular systems suggest that neo-inositol derivatives undergo conformational change prior to radical formation while myo- inositol derivatives undergo conformational change subsequent to radical formation, during the deoxygenation reaction. A low barrier for intramolecular hydrogen transfer supports the extreme facility of this deoxygenation reaction. (C) 2012 Elsevier Ltd. All rights reserved.

10aDeoxygenation10aDFT10aInositol10aMechanism10aRadical10aXanthate1 aGurale, Bharat, P.1 aVanka, Kumar1 aShashidhar, Mysore, S. uhttps://library.ncl.res.in/content/radical-mediated-deoxygenation-inositol-benzylidene-acetals-conformational-analysis-dft-001515nas a2200217 4500008004100000022001400041245010000055210006900155260011000224300001600334490000700350520068400357100001901041700001801060700002301078700001701101700001901118700001701137700001901154856012401173 2016 eng d a1477-922600aReductive nitrosylation of nickel(II) complex by nitric oxide followed by nitrous oxide release0 aReductive nitrosylation of nickelII complex by nitric oxide foll aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAY a10200-102080 v453 a

Ni(II) complex of ligand L (L = bis(2-ethyl-4-methylimidazol-5-yl)methane) in methanol solution reacts with an equivalent amount of NO resulting in a corresponding Ni(I) complex. Adding further NO equivalent affords a Ni(I)-nitrosyl intermediate with the {NiNO}(10) configuration. This nitrosyl intermediate upon subsequent reaction with additional NO results in the release of N2O and formation of a Ni(II)-nitrito complex. Crystallographic characterization of the nitrito complex revealed a symmetric eta(2)-O,O-nitrito bonding to the metal ion. This study demonstrates the reductive nitrosylation of a Ni(II) center followed by N2O release in the presence of excess NO.

1 aGhosh, Somnath1 aDeka, Hemanta1 aDangat, Yuvraj, B.1 aSaha, Soumen1 aGogoi, Kuldeep1 aVanka, Kumar1 aMondal, Biplab uhttps://library.ncl.res.in/content/reductive-nitrosylation-nickelii-complex-nitric-oxide-followed-nitrous-oxide-release02657nas a2200169 4500008004100000022001400041245009800055210006900153260000800222300001200230490000800242520205600250100001902306700002702325700001702352856011802369 2018 eng d a1932-744700aRole of the (104) MgCl2 lateral cut in ziegler-natta catalysis: a computational investigation0 aRole of the 104 MgCl2 lateral cut in zieglernatta catalysis a co cJAN a285-2960 v1223 a

Density functional theory (DFT) has been used for the study of ethylene polymerization in the Ziegler-Natta (ZN) olefin polymerization system for eight different alkoxy group containing titanium catalysts (Cat-A-h), Ti(III)Et(OR)(OR') (where R =-CH3,-Et,-tert-butyl, cyclohexane, R' = CH3,-Et,-tert-butyl, cyclohexane). What is of significance is that the catalysts studied were all considered to be tethered to the (104) MgCl2 surface, which has traditionally been considered a ``dormant'' surface in Z-N catalysis systems, in contrast to the ``more active'' (110) MgCl2 surface. Our calculations indicate that the binding of all the catalysts to the (104) surface is favorable, even after taking entropic effects into account. For purposes of comparison, ethylene polymerization has been investigated for the Cat-C (TiEt(OEt)(2)) and the Cat-H (TiEt(CI)(OC4H8Cl)) (OC4H8Cl = the chlorobutoxy group) cases, for both the (i) (110) and the (ii) (104) MgCl2 surfaces. It has been seen that for both (i) and (ii)-the energy gap between insertion and the termination barriers (Delta X) was nearly the same for both the Cat-C and Cat-H eases, which shows that ethylene polymerization on the (104)MgCl2 surface is likely to be a ptoininent occurrence in Z-N catalysis, when alkoxy groups are bound to the titanium center. Additionally, for the Cat-C and the Cat-H cases, the regio-and stereoselective behavior of the propylene monomer on the titanium species present on the (110) and the (104) MgCl2 surfaces has also been investigated, and the results indicate that the (104) MgCl2 surface is only slightly less effective than the (110. However, the calculations also indicate that for Cat-H the (104) MgCl2 surface significantly improves the molecular weight of polypropylene in comparison to the (110) surface, further showcasing how the (104) surface (ignored until date) might be a major player in ZN catalysis. Given that a major portion of the MgCl2 support is made up of (104) lateral cuts, the current findings are of considerable relevance.

1 aKumawat, Jugal1 aGupta, Virendra, Kumar1 aVanka, Kumar uhttps://library.ncl.res.in/content/role-104-mgcl2-lateral-cut-ziegler-natta-catalysis-computational-investigation01608nas a2200193 4500008004100000022001400041245010300055210006900158260001100227300001100238490000800249520094000257100002401197700001801221700001501239700001701254700001901271856012401290 2021 eng d a0022-328X00aReadily available lithium compounds as catalysts for the hydroboration of carbodiimides and esters0 aReadily available lithium compounds as catalysts for the hydrobo cSEP 15 a1219240 v9493 aSelective and efficient hydroboration of esters and carbodiimides to alcohols and amines by two welldefined and readily accessible lithium complexes, 2,6-di-tert-butyl phenolate lithium (1a ) and 1,1'-dilithioferrocene (1b ) are described. A range of aliphatic, aromatic, and cyclic esters with various functional groups were selectively converted into the corresponding boronate esters. Similarly, the single hydroboration of carbodiimides with aliphatic and aromatic substituents on the nitrogen atoms was studied. A possible mechanistic pathway of the hydroboration of carbodiimides with HBpin has been proposed using NMR studies and DFT calculations. These reactions are convenient alternatives to stoichiometric hydride reduction or hydrogenation. The employing of lithium complexes is also significant, because of the need to find cheap and green alternatives to noble metal complexes. (C) 2021 Elsevier B.V. All rights reserved.1 aBisai, Milan, Kumar1 aGour, Kritika1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/readily-available-lithium-compounds-catalysts-hydroboration-carbodiimides-and-esters02512nas a2200265 4500008004100000022001400041245010800055210006900163260000800232300001100240490000800251520162600259653001801885653001401903653002001917653001801937653002301955653002601978100002302004700002102027700001702048700002602065700002502091856013002116 2022 eng d a0022-328X00aReactivity of four coordinate iridium complex towards hydrogen: an experimental and computational study0 aReactivity of four coordinate iridium complex towards hydrogen a cMAY a1223170 v9653 a

Reaction of a four coordinate, 16-electron Ir complex, [Ir-(iPr)4(POCOP)(PPh3)] (4 ) (((iPr)4)(POCOP= 2,6-bis(di-isopropyl phosphinito)benzene, kappa(3)-C6H3-1,3-[OP((iPr))(2)](2)), with H-2 resulted in an oxidative addition product, cis-dihydride complex, cis-[Ir(H)(2) ((iPr)4)(POCOP)(PPh3)] ( cis-5 ) presumably via the intermediacy of a sigma complex, [Ir(eta(2)-H-2)((iPr)4)(POCOP)(PPh3)]. The cis-dihydride complex completely isomerizes to the trans-dihydride complex trans-[Ir(H)(2) ((iPr)4)(POCOP)(PPh3)] ( trans-5 ) under ambient conditions in about 3 h. It was found that the steric and electronic features on the iridium center have significant influence on the approach of H-2 onto the metal center followed by oxidative addition and isomerization. The isomerization process was studied in detail and all the mechanistic aspects have been elucidated using a combination of both experimental work and computation. The cis-dihydride complex isomerizes to the trans-dihydride by compensating the trans influence of the strongly trans-directing hydride ligand. A mechanism involving the exchange of the position of PPh3 with a hydride ligand cis to itself via PPh3 dissociation and re-coordination thereby resulting in the formation of the trans-dihydride complex, has been proposed for the isomerization. The cis-dihydride was found to be a highly active catalyst for hydrogenation of ethy-lene. A competing reactivity study of cis-dihydride between isomerization versus insertion of C2H4 into the Ir-H bond, was studied experimentally and computationally. (c) 2022 Elsevier B.V. All rights reserved.

10aHydrogenation10aInsertion10airidium complex10aisomerization10aOxidative addition10aReductive elimination1 aAgrawal, Nisha, K.1 aDash, Soumya, R.1 aVanka, Kumar1 aNethaji, Munirathinam1 aJagirdar, Balaji, R. uhttps://library.ncl.res.in/content/reactivity-four-coordinate-iridium-complex-towards-hydrogen-experimental-and-computational02391nas a2200205 4500008004100000022001400041245013400055210006900189260000900258300001600267490000700283520164000290100002301930700002301953700001901976700002401995700001702019700002002036856012902056 2022 eng d a2041-652000aRoom temperature chemoselective hydrogenation of C=C, C=O and C=N bonds by using a well-defined mixed donor Mn(I) pincer catalyst0 aRoom temperature chemoselective hydrogenation of CC CO and CN bo cNOV  a13764-137730 v133 a

Chemoselective hydrogenation of C=C, C=O and C=N bonds in alpha,beta-unsaturated ketones, aldehydes and imines is accomplished at room temperature (27 degrees C) using a well-defined Mn(I) catalyst and 5.0 bar H-2. Amongst the three mixed-donor Mn(I) complexes developed, kappa(3)-((PNNPyz)-P-R2-N-3)Mn(CO)(2)Br (R = Ph, Pr-i, Bu-t); the Bu-t -substituted complex ((PNNPyz)-P-tBu2-N-3)Mn(CO)(2)Br shows exceptional chemoselective catalytic reduction of unsaturated bonds. This hydrogenation protocol tolerates a range of highly susceptible functionalities, such as halides (-F, -Cl, -Br, and -I), alkoxy and hydroxy, including hydrogen-sensitive moieties like acetyl, nitrile, nitro, epoxide, and unconjugated alkenyl and alkynyl groups. Additionally, the disclosed method applies to indole, pyrrole, furan, thiophene, and pyridine-containing unsaturated ketones leading to the corresponding saturated ketones. The C=C bond is chemoselectively hydrogenated in alpha,beta-unsaturated ketones, while the aldehyde's C=O bond and imine's C=N bond are preferentially reduced over the C=C bond. A detailed mechanistic study highlighted the non-innocent behavior of the ligand in the ((PNNPyz)-P-tBu2-N-3) Mn(I) complex and indicated a metal-ligand cooperative catalytic pathway. The molecular hydrogen (H-2) acts as a hydride source, whereas MeOH provides a proton for hydrogenation. DFT energy calculations supported the facile progress of most catalytic steps, involving a crucial turnover-limiting H-2 activation.

1 aShabade, Anand, B.1 aSharma, Dipesh, M.1 aBajpai, Priyam1 aGonnade, Rajesh, G.1 aVanka, Kumar1 aPunji, Benudhar uhttps://library.ncl.res.in/content/room-temperature-chemoselective-hydrogenation-cc-co-and-cn-bonds-using-well-defined-mixed02779nas a2200217 4500008004100000245010100041210006900142260000900211300001400220490000700234520201600241100002502257700002402282700002102306700002702327700001902354700001702373700001802390700002402408856012902432 2023 eng d00aRivaroxaban eutectics with improved solubility, dissolution rates, bioavailability and stability0 aRivaroxaban eutectics with improved solubility dissolution rates cJUN  a3253-32630 v253 a

Rivaroxaban (RXB) is a direct factor Xa inhibitor used for the treatment of deep vein thrombosis (DVT, a blood clot in the leg) and pulmonary embolism (PE, a blood clot in the lung) and to prevent blood clots in atrial fibrillation following hip or knee surgery. However, RXB suffers from poor solubility that hinders its broader application. Although its cocrystals are reported for solubility enhancement, the methodology used to prepare multi-component crystals is complex. Also, it uses hazardous solvents to develop cocrystals. We have prepared eutectics of RXB with caffeic acid (CAA), coumaric acid (CA), fumaric acid (FA), succinic acid (SA), mandelic acid (MA) and trimesic acid (TA) and analyzed them using hot stage microscopy (HSM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and fourier transform infrared spectroscopy (FTIR) techniques. The saturation solubility and dissolution rate profiles were also obtained to investigate the effect of eutectics on these parameters. Amongst all the coformers tested, coformers CAA, CA, and FA showed significant enhancement in the solubility of RXB. The powder dissolution rate of the eutectics showed considerable enhancement compared to that of RXB. In vivo pharmacokinetic study was carried out for RXB-CAA, RXB-CA and RXB-FA in rats and compared with RXB, which showed 1.5 and 1.4 times enhancement in relative bioavailability for RXB-CAA and RXB-CA, respectively. Stability studies were carried out as per ICH guidelines for all the eutectics, which revealed excellent stability over six months under accelerated (40 degrees C and 75%) conditions and twelve months under long-term (30 degrees C and 60% RH) conditions. The DFT studies carried out using the B3LYP/TZVP level of theory revealed higher Gibbs free interaction energy (Delta G(int)) for homosynthons (drugMIDLINE HORIZONTAL ELLIPSISdrug and coformerMIDLINE HORIZONTAL ELLIPSIScoformer) than heterosynthons (drugMIDLINE HORIZONTAL ELLIPSIScoformer).

1 aShaligram, Parth, S.1 aGeorge, Christy, P.1 aSharma, Himanshu1 aMahadik, Kakasaheb, R.1 aPatil, Sharvil1 aVanka, Kumar1 aArulmozhi, S.1 aGonnade, Rajesh, G. uhttps://library.ncl.res.in/content/rivaroxaban-eutectics-improved-solubility-dissolution-rates-bioavailability-and-stability01687nas a2200181 4500008004100000245011000041210006900151260000800220300001400228490000600242520102800248100002301276700002101299700002101320700001701341700001601358856013101374 2024 eng d00aRational monomer design for the synthesis of conjugated polymers by direct heteroarylation polymerization0 aRational monomer design for the synthesis of conjugated polymers cJUL a449–4590 v43 a

This study focuses on the design concepts that contribute to the C–H activation in bithiophene-flanked monomers incorporating naphthalene diimide (NDI), perylene diimide (PDI), and fluorene (FLU) and their polymerization by direct heteroarylation. Density functional theory (DFT) calculations reveal distinct energy requirements for C–H bond abstraction, which is dictated by the electron-withdrawing strength of the central aromatic core flanked by bithiophene. These provide insights into the reactivity of each monomer for C–H bond activation. Proton NMR spectroscopic experimental results confirm the favorable energetic profiles predicted by DFT, with NDI- and PDI-flanked monomers exhibiting lower energy requirements than fluorene-flanked monomers. Successful polymer synthesis is demonstrated for NDI and PDI, while the fluorene-flanked monomer shows challenges due to its higher energy demands.

1 aKakde, Navnath, R.1 aSharma, Himanshu1 aDalvi, Nitin, V.1 aVanka, Kumar1 aAsha, S., K uhttps://library.ncl.res.in/content/rational-monomer-design-synthesis-conjugated-polymers-direct-heteroarylation-polymerization02385nas a2200205 4500008004100000022001400041245010100055210006900156260000900225490000700234520164100241653001301882653003101895653002201926653003001948653003501978100002502013700001702038856012402055 2024 eng d a1861-472800aRole of aromatic alcohol additives on asymmetric organocatalysis reactions: insights from theory0 aRole of aromatic alcohol additives on asymmetric organocatalysis cFEB 0 v193 a

The presence of an aromatic additive has been seen to enhance, often significantly, the enantioselectivity and yield in asymmetric organocatalysis. Considering their success across a dizzying range of organocatalysts and organic transformations, it would seem unlikely that a common principle exists for their functioning. However, the current investigations with DFT suggest a general principle: the phenolic additive sandwiches itself, through hydrogen bonding and pi & sdot;& sdot;& sdot;pi stacking, between the organocatalyst coordinated electrophile and nucleophile. This is seen for a wide range of experimentally reported systems. That such complex formation leads to enhanced stereoselectivity is then demonstrated for two cases: the cinchona alkaloid complex (BzCPD), catalysing thiocyanation (2-naphthol additive employed), as well as for L-pipecolicacid catalysing the asymmetric nitroaldol reaction with a range of nitro-substituted phenol additives. These findings, indicating that dual catalysis takes place when phenolic additives are employed, are likely to have a significant impact on the field of asymmetric organocatalysis. The current DFT based study, on a wide range of organocatalysis systems, reveals a general principle by which phenolic additives influence asymmetric organocatalysis reactions. It is shown that the phenolic additive forms a sandwich complex, through hydrogen bonding and pi & sdot;& sdot;& sdot;pi stacking interactions, with the organocatalyst coordinated electrophile and nucleophile, and enhances the enantioselectivity of the system as a result. image

10aAdditive10aAsymmetric Organocatalysis10aCinchona Alkaloid10aDensity functional theory10aEnantioselective Thiocyanation1 aBanerjee, Subhrashis1 aVanka, Kumar uhttps://library.ncl.res.in/content/role-aromatic-alcohol-additives-asymmetric-organocatalysis-reactions-insights-theory