03178nas a2200169   4500008004100000245012700041210006900168260000800237300001600245490000700261520253100268100002202799700001702821700001902838700002402857856012702881       2017                        eng d00a Self-assembly of P-chiral supramolecular phosphines on rhodium and direct evidence for Rh-catalyst-substrate interactions0 aSelfassembly of Pchiral supramolecular phosphines on rhodium and  cOCT  a13966-139730 v463 aSupramolecular phosphine-derived catalysts are known to provide high enantioselectivity in asymmetric transformations such as hydrogenation, but direct evidence unravelling the role of secondary interactions is largely missing. As a representative case study, the role of hydrogen bonding in asymmetric hydrogenation catalysed by p-chiral supramolecular phosphines is investigated. To establish the nature of hydrogen bonding in the self-assembled Rh-complex, NMR experiments were performed at different concentrations and temperatures. It was found that with increasing concentration of 1-(3-(phenyl(o-tolyl)phosphanyl) phenyl) urea ligand (L1), the NH and NH2 peaks shift downfield. This indicated the presence of intermolecular hydrogen bonding in L1. This observation was further supported by variable temperature NMR experiments wherein, with decreasing temperature, the NH and NH2 resonances of L1 shifted downfield. The downfield shift once again suggests the existence of intermolecular hydrogen bonding in L1. In contrast, the chemical shift of NH and NH2 signals did not significantly change with increasing concentration of the self-assembled Rh-complex (C1). This observation suggested the existence of intramolecular hydrogen bonding in the self-assembled complex. The concentration experiment was further corroborated by variable temperature NMR experiments. No change in the chemical shift of NH2 resonance could be detected with decreasing temperature, which corroborates the existence of intramolecular hydrogen bonding in C1. In a stoichiometric experiment, C1 was treated with hydrogenation substrate N-acetyldehydrophenylalanine (S2) and the proton NMR was recorded. The NH2 protons of the selfassembled Rh-complex were found to shift downfield, as compared to untreated parent C1. These observations indicated that there is a hydrogen bonding interaction between the Rh-complex and the substrate. To further attest this hypothesis, NH and NH2 groups were exchanged with ND and ND2 groups, respectively, and a self-assembled Rh-complex was prepared using the deuterated supramolecular phosphine ligand L1.D. When the deuterated Rh-complex (C1.D) was treated with substrate S2, the ND and ND2 resonances were found to shift downfield. Thus, the labelling experiment further authenticated the existence of catalyst-substrate interactions. The presence of this catalyst-substrate interaction could be one of the parameters that leads to high enantiomeric excess in the asymmetric hydrogenation reaction of S2.1 aKoshti, Vijay, S.1 aSen, Anirban1 aShinde, Dinesh1 aChikkali, Samir, H.  uhttp://library.ncl.res.in/content/self-assembly-p-chiral-supramolecular-phosphines-rhodium-and-direct-evidence-rh-catalyst01240nas a2200289   4500008004100000022001400041245005300055210005300108260000800161300001200169490000600181520040000187653002900587653001400616653002200630653001200652653001600664100002000680700001700700700002700717700002400744700002500768700002500793700002400818700002400842856008400866       2020                        eng d  a2193-580700aHighly enantioselective synthesis of sitagliptin0 aHighly enantioselective synthesis of sitagliptin  cFEB  a189-1910 v93 a<p>A highly enantioselective synthesis of sitagliptin, a potent DPP-4 inhibitor, is reported. Explicitly identified chiral FerroLANE ligands in the presence of rhodium catalyze the asymmetric hydrogenation of an enamine to yield sitagliptin with excellent enantioselectivity (98% ee). The process was scaled up to 5 g and the final product was isolated as a phosphate salt with &gt;99% ee.</p>
10aasymmetric hydrogenation10acatalysis10aFerroLANE ligands10aRhodium10asitagliptin1 aKhopade, Kishor1 aSen, Anirban1 aBirajdar, Rajkumar, S.1 aPaulbudhe, Uday, P.1 aKavale, Dattatry, S.1 aShinde, Prashant, S.1 aMhaske, Santosh, B.1 aChikkali, Samir, H.  uhttp://library.ncl.res.in/content/highly-enantioselective-synthesis-sitagliptin02157nas a2200157   4500008004100000022001400041245011300055210006900168260000900237300001400246490000700260520156200267100001701829700002401846856012901870       2021                        eng d  a1477-052000aC (1)-Symmetric diphosphorus ligands in metal-catalyzed asymmetric hydrogenation to prepare chiral compounds0 aC 1Symmetric diphosphorus ligands in metalcatalyzed asymmetric h  cNOV   a9095-91370 v193 aAsymmetric hydrogenation has remained an important and challenging research area in industry as well as academia due to its high atom economy and ability to induce chirality. Among several types of ligands, chiral bidentate phosphine ligands have played a pivotal role in developing asymmetric hydrogenation. Although C-2-symmetric chiral bidentate phosphine ligands have dominated the field, it has been found that several C-1-symmetric ligands are equally effective and, in many cases, have outperformed their C-2-symmetric counterparts. This review evaluates the possibility of the use of C-1-symmetric diphosphorus ligands in asymmetric hydrogenation to produce chiral compounds. The recent strategies and advances in the application of C-1-symmetric diphosphorus ligands in the metal-catalyzed asymmetric hydrogenation of a variety of C=C bonds have been summarized. The potential of diphosphorus ligands in asymmetric hydrogenation to produce pharmaceutical intermediates, bioactive molecules, drug molecules, agrochemicals, and fragrances is discussed. Although asymmetric hydrogenation appears to be a problem that has been resolved, a deep dive into the recent literature reveals that there are several challenges that are yet to be addressed. The current asymmetric hydrogenation methods mostly employ precious metals, which are depleting at a fast pace. Therefore, scientific interventions to perform asymmetric hydrogenation using base metals or earth-abundant metals that can compete with established precious metals hold significant potential.1 aSen, Anirban1 aChikkali, Samir, H.  uhttp://library.ncl.res.in/content/c-1-symmetric-diphosphorus-ligands-metal-catalyzed-asymmetric-hydrogenation-prepare-chiral02052nas a2200277   4500008004100000022001400041245011600055210006900171260000800240300001500248490000900263520112800272653002901400653001401429653001901443653002201462653003101484100001701515700001701532700002201549700001501571700001701586700001701603700002401620856013001644       2022                        eng d  a1434-193X00aMechanistically guided one pot synthesis of phosphine-phosphite and its implication in asymmetric hydrogenation0 aMechanistically guided one pot synthesis of phosphinephosphite a  cJAN  ae2021014470 v20223 a<p>
	Although hybrid bidentate ligands are known to yield highly enantioselective products in asymmetric hydrogenation (AH), synthesis of these ligands is an arduous process. Herein, a one pot, atom-economic synthesis of a hybrid phosphine-phosphite (L1) is reported. After understanding the reactivity difference between an 0-nucleophile versus C-nucleophile, one pot synthesis of Senphos (L1) was achieved (72%). When L1 was treated with [Rh], P-31 NMR revealed bidentate coordination to Rh. Senphos, in the presence of rhodium, catalyzes the AH of Methyl-2-acetamido-3-phenylacrylate and discloses an unprecedented turn over frequency of 2289, along with excellent enantio-selectivity (92%). The generality is demonstrated by hydrogenating an array of alkenes. The AH operates under mild conditions of 1-2 bar H-2 pressure, at room temperature. The practical relevance of Ll is demonstrated by scaling-up the reaction to 1 g and by synthesizing DOPA, a drug widely employed for the treatment of Parkinson's disease. Computational insights indicate that the R isomer is preferred by 3.8 kcal/mol over the S isomer.</p>
10aasymmetric hydrogenation10acatalysis10aDOPA synthesis10aOne pot synthesis10aPhosphine-phosphite ligand1 aSen, Anirban1 aKumar, Rohit1 aPandey, Swechchha1 aRaj, Vipin1 aKumar, Pawan1 aVanka, Kumar1 aChikkali, Samir, H.  uhttp://library.ncl.res.in/content/mechanistically-guided-one-pot-synthesis-phosphine-phosphite-and-its-implication-asymmetric