Asymmetric Reductions of Carbon-Nitrogen Double Bonds. A Review

Catalytic Enantioselective Addition to Imines

“…In 1973, Kagan et al reported the first example of catalytic enantioselective reductions (hydrosilylation) of imines, and 50% ee of the amine was obtained in the reduction of N- (α-methylbenzylidene)benzylamine ( 1 ) . Since then, many chemists have made effort to develop highly enantioselective reduction processes (eq 1) …”

Enzymatic Resolution of Bicyclic 1-Heteroarylamines Using Candida antarctica Lipase B

“…Given the importance of chiral amines as building blocks in medicinal chemistry and as scaffolds for chiral ligands, efficient and cost-effective methods for the preparation of optically active amines are highly sought after. Traditional synthetic methods to access enantioenriched amines employ either stoichiometric chiral reagents and auxiliaries or chiral catalysts for reduction of amine precursors such as oximes, imines, hydrazones, and enamides . In contrast to these approaches, the preparation of optically active amines via lipase-catalyzed enantioselective acetylation can be accomplished using mild conditions, inexpensive and nontoxic reagents, and facile experimental procedures .…”

Amination Reactions

“…[74][75][76][77][78]). An early example [79] is the amination of α-keto acids with (R)-(+)-or (S)-(−) -α-methylbenzylamine to the corresponding N -alkyl-α-amino acids (or α-amino acids after a further debenzylation step over Pd/C), according to Scheme 7.…”

“…Several other diastereoselective amination reactions of carbonyl compounds -including α-keto acids, amides and esters, aliphatic and cycloaliphatic ketones, and diketones -have since been reported [74,77,80]. The crucial reaction parameters, which influence the magnitude of diastereoselective excess, are the temperature, solvent polarity, catalyst : reactant ratio and the dispersion and pretreatment of the catalyst [81].…”