Reactions of pyridine ketones with dicyclopentylzinc

Abstract

The mechanism of spontaneous chirality generation remains not sufficiently explored, and compounds with a structure significantly different from the known Soai substrates are elusive. Recently we reported enantioselective reduction of 3-acetylpyridine with dicyclopentylzinc in the presence of a chiral catalyst. In this work, the interaction of 2- and 3-pyridyl ketones with dicyclopentylzinc in the absence and presence of a chiral catalyst was investigated. It is shown that all ketones are reduced by the organozinc reagent to the corresponding secondary alcohols. Low enantioselectivity (28% ee) was observed only in the reaction of a 3-acetylpyridine derivative carried out in the presence of a chiral amino alcohol. To explain the stereoselectivity of 3-acetylpyridine reduction, quantum chemical calculations were used.