A Convenient Synthesis of 2-Substituted Thiazole-5-carboxylates

Abstract

The photolysis of ethyl 5-oxo-2-phenyl-2,5-dihydroisoxazole-4-carboxylate in acetonitrile containing 0.5% tri- fluoroacetic acid in the presence of thioamides gives moderate (40–60%) yields of thiazole-5-carboxylate esters. In the absence of trifluoroacetic acid, the intermediate vinyl thioesters can be isolated. That addition of the thioamide to the first formed carbene was, through sulfur, confirmed by X-ray crystal structures of 2-methylthiazole-5-carboxylic acid and a byproduct.