Research Projects

Catalytic asymmetric hydrogenation of prochiral substrates such as C=O, C=N and C= C is one of the most elegant methods for the synthesis of optically active chiral molecules.1 Catalytic asymmetric hydrogenation reactions are well-known green approach since it utilizes molecular hydrogen and generates nondetrimental waste. It has been magnificently applied in industry sectors for the synthesis of chiral amines, heterocycles, amides, chiral amino acids, alkanes and alcohols, in enantioenriched form.2 Magnifying the extensive use of chiral amines in medicines, natural products, direct access to enantiopure amines by ketimine hydrogenation turns out a key research topic in academe and industry. Among different strategies for synthesizing chiral amine the direct catalytic hydrogenation of respective ketimine is highly convenient because of their green nature and is reported mainly with transition metals.4 The first attempt to ketimine asymmetric hydrogenation was pioneered by Scorrano using a chiral 1,4-bisphosphine based rhodium complex [Rh(NBD)(DIOP)]+ClO4 − with significantly lower enentioselectivity.5(a) Significant improvement were achieved in enantioselectivity of Rh catalyzed cyclic imine hydrogenation using TsDPEN ligand and Cp*Rh(III) catalyst. Morris and coworkers developed diphosphine and diamine supported RuHCl complex for stereoselective imine hydrogenation.6 Thereafter, palladium,7a iridium7b catalyzed AIH have been reported from various research group. First row transition metal catalyst such as cobalt7c and iron7d have a few reports with sluggish reactivity, limited scope and poor enantioselectivity. Despite of these published methodologies, development of eco-benign asymmetric synthesis route utilizing abundantly available inexpensive 3d-transition metals for this hydrogenation are still in an emerging field.2,8 Thus the use of Ni and Mn for these developments is a predominant goal. In this research proposal, judicious design and synthesis non-toxic, earth abundant chiral Mn and Ni-metal complexes are anticipated to avail this target. (L)-phenylalanine is cheap readily available, stable, environment friendly and retain its chirality effortlessly. Modified (L)- phenylalanine donor based based pincer type ligand synthesis and corresponding metal complexes are scarcely reported.9 This catalytic protocol projected to synthesize top selling drug molecules (S)-Anabasine, (R)-Tamsulosin, (S)-Mavacamten which are used as insecticide, enlarged prostate gland and symptomatic obstructive hypertrophic cardiomyopathy (HCM)and bioactive molecules such as (S)-Salsolidine and (-)-Cuspareine, (-Aungustureine and (S)-Carnegine.10