Chemistry of Sodium Borohydride and Diborane. IV. Reduction of Carboxylic Acids to Alcohols with Sodium Borohydride through Mixed Carbonic-Carboxylic Acid Anhydrides

Abstract

Mixed carbonic-carboxylic acid anhydrides, prepared in situ from carboxylic acids and ethyl chloroformate, were reduced with sodium borohydride in aqueous tetrahydrofuran to the corresponding alcohols in fair yields. Under the reaction condition examined, it was possible to reduce carboxyl group selectively to hydroxymethyl group in carboxylic acids having functional groups such as nitro-, cyano-, amido-, ester-group, and conjugated double bond. The general procedure for this reaction is given.