Synthesis of Acetylenic Carboxylic Acids

Abstract

A recent communication by Brattesani and Heathcock¹ on the alkylation of acetylenes with alkyl halides in hexamethylphosphoramide (HMPA) prompts us to report our work which is of a similar nature. We were interested in preparing acetylenic acids of formula 1 by either of the following two routes:

The published procedure, which gives variable results, for the preparation of acetylenic acids via route (1) involves the condensation of a lithio-alkyne with an ωl -bromo-acid in liquid ammonia-tetrahydrofuran.