Asymmetric induction in the borohydride reduction of carbonyl compounds by means of chiral phase-transfer catalysts. Part 2

Abstract

Reaction of carbonyl compounds with sodium borohydride in a two-phase system, in the presence of chiral ammonium salts containing a secondary hydroxy-group affords the corresponding carbinols with 0–32% enantiomeric excess. The optical yields are higher when the hydroxy group is β to the ‘onium’ function and the catalyst is conformationally more rigid.