Acetylenic acids. III. The synthesis of pyridylpropiolic acids and esters and their reaction with thionyl chloride

Abstract

A variety of synthetic routes to pyridinylpropiolic acids and esters have been investigated. The most convenient route to the esters involves the formation of the corresponding ethyl 3-oxo-3-pyridinyl-2-triphenylphosphoranediylpropanoates and their subsequent pyrolysis. The acids can be obtained by careful hydrolysis of the esters. The reaction of thionyl chloride with these compounds has been examined; in one case a low yield of a thieno[2,3-b]pyridine was obtained.