01295nas a2200157 4500008004100000245010200041210006900143260000800212300001400220490000700234520070900241100001800950700002300968700002000991856012601011 2018 eng d00a Nickel-catalyzed regioselective C(2)-H difluoroalkylation of indoles with difluoroalkyl bromides0 aNickelcatalyzed regioselective C2H difluoroalkylation of indoles cSEP a2516-25210 v133 aRegioselective C(2)-H difluoroalkylation of C-3 unsubstituted indoles with commonly available fluoroalkyl bromides is successfully achieved employing a simple nickel catalyst system, (DME)NiCl2/Xantphos. This methodology shows excellent regioselectivity and exhibits a broad substrate scope. Various functional groups, such as -OMe, -F, and -Br, are tolerated on the indole backbone to give the difluoroalkylated products in moderate to good yields. Preliminary mechanistic findings demonstrate that the reaction is homogeneous in nature and involves a radical manifold. Synthetic utility of this nickel-catalyzed method is demonstrated by synthesizing melatonin receptor antagonist Luzindole derivative.1 aSoni, Vineeta1 aSharma, Dipesh, M.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/nickel-catalyzed-regioselective-c2-h-difluoroalkylation-indoles-difluoroalkyl-bromides01222nas a2200145 4500008004100000245009300041210006900134260000800203300001400211490000800225520068500233100002300918700002000941856011500961 2019 eng d00aSelective synthesis of secondary amines from nitriles by a user-friendly cobalt catalyst0 aSelective synthesis of secondary amines from nitriles by a userf cSEP a3930-39360 v3613 a

Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3-BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH-BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities.
 

1 aSharma, Dipesh, M.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/selective-synthesis-secondary-amines-nitriles-user-friendly-cobalt-catalyst01572nas a2200217 4500008004100000022001400041245007300055210006900128260000800197300001200205490000700217520089300224653002401117653001201141653001801153653001301171653002201184100002301206700002001229856010501249 2020 eng d a1861-472800a3 d transition metal-catalyzed hydrogenation of nitriles and alkynes0 a3 d transition metalcatalyzed hydrogenation of nitriles and alky cMAR a690-7080 v153 a

Selective hydrogenation of nitriles and alkynes is crucial considering the vast applications of reduced products in industries and in the synthesis of bioactive compounds. Particularly, the late 3d transition metal catalysts (manganese, iron, cobalt, nickel and copper) have shown promising activity for the hydrogenation of nitriles to primary amines, secondary amines and imines. Similarly, semihydrogenation of alkynes to E- and Z-alkenes by 3d metals is adequately successful both via the transfer hydrogenation and by using molecular hydrogen. The emergence of 3d transition metals in the selective synthesis of industrially relevant amines, imines and alkenes makes this protocol more attractive. Herein, we provide a concise overview on the late 3d transition metal-catalyzed hydrogenation of nitriles to amines and imines as well as semihydrogenation of alkynes to alkenes.

10a3d transition metal10aAlkynes10aHydrogenation10anitriles10aSemihydrogenation1 aSharma, Dipesh, M.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/3-d-transition-metal-catalyzed-hydrogenation-nitriles-and-alkynes02391nas 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-mixed01654nas a2200181 4500008004100000022001400041245011100055210006900166260000900235300001400244490000700258520099100265100002301256700002301279700002401302700002001326856012601346 2022 eng d a2044-475300aRoom temperature Z-selective hydrogenation of alkynes by hemilabile and non-innocent (NNN)Co(ii) catalysts0 aRoom temperature Zselective hydrogenation of alkynes by hemilabi cMAR  a1843-18490 v123 a

Hemilabile and phosphine-free quinolinyl-based NNN-type pincer and non-pincer cobalt complexes were developed for the room temperature catalytic transfer semi-hydrogenation of alkynes to Z-alkenes. Treatment of the quinolinyl-amine ligand, [C9H6N(NH)CH2CH2NEt2] ((NNN2NEt2)-N-Q-N-CH)-H with CoX2 afforded the pincer complexes kappa(3)-((NNN2NEt2)-N-Q-N-CH)CoX2 (X = Cl, Br), whereas, the quinolinyl-amide ligand, [C9H6N(NH)C(O)CH2NEt2] ((NNNNEt2)-N-Q-N-C(O))-H gave chelate anionic complexes kappa(2)-((NN)-N-Q)CoX2((NHNEt2)-H-C(O)) (X = Cl, Br). The well-defined anionic non-pincer cobalt complexes efficiently catalyzed the semi-hydrogenation of diverse alkynes to deliver highly chemoselective and stereodivergent Z-alkenes at room temperature. This hydrogenation exhibited broad substrate scope with the tolerance of sensitive functional groups, such as -Cl, -Br, -I, -OH, -NH2, -COOMe, and pyridinyl, employing a stable and user-friendly ammonia borane hydrogen source.

1 aSharma, Dipesh, M.1 aGouda, Chandrakant1 aGonnade, Rajesh, G.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/room-temperature-z-selective-hydrogenation-alkynes-hemilabile-and-non-innocent-nnncoii