Kowalski Ester Homologation

Abstract

The one‐carbon extension of a carboxylic acid chain of an ester with methylene dibromide by means of strong base treatment at very low temperature and quenched by an alcohol is known as the Kowalski homologation. This reaction has obvious advantages over the Arndt–Eistert synthesis, and also bears some limitations. The two‐step modification of the reaction increases the yield but also scales up the reaction. Besides the general extension of an ester carbon chain, this reaction has wide application for the synthesis of β‐amino acid ester with retention of stereochemistry and the siloxyacetylene derivatives.