Improvement in the enantioselectivity of the hydrogen transfer with NADH models bearing amino alcohols as chiral auxiliaries

Abstract

Chiral amino alcohols have been linked to the γ-carbonyl group of the 5,7-dihydrothieno[2,3b]pyridines (4a–d). These models are much more easily handled in mild conditions than common NADH models. The factors affecting enantiomeric excess have been studied, e.g, influence of temperature, polarity of solvents, magnesium concentration, and hydrogen bonding. By appropriate modifications of the chiral auxiliary, the rigidity of the ternary complex: model–Mg²⁺–substrate involved has been enhanced. In this way a high enantiomeric excess has been obtained.