Reduction by a Model of NAD(P)H. 33. Steric and Electronic Effects on Asymmetric Reduction of 2-Acylpyridines

Abstract

Abstract Series of alkyl and fluorinated alkyl 2-pyridinyl ketones have been reduced by a chiral NAD(P)H-model (Me2PNPH) in the presence of magnesium ion in acetonitrile. Optical yield decreases in the order of substituent: CH3>C2H5>C(CH3)3>CH(CH3)2 and CH3>CH2F>CHF2>CF3. The results have been interpreted in terms of conformation of the substrates for alkyl 2-pyridinyl ketones and of electronic competitional effect between two substituents for fluorinated alkyl 2-pyridinyl ketones. Magnesium ion freezes intermolecular arrangement at the transition state of the reduction.