The synthetic utility of heteroaromatic azido compounds. Part VI. Preparation of some 1<i>H</i>‐1,2,3‐triazolo[1,5‐<i>a</i>]thieno[3,2‐<i>d</i>]pyrimidines

Abstract

Abstract Some 1,2,3‐triazolo[1,5‐ a ]thieno[3,2‐ d ]pyrimidines have been prepared by the reaction of active methylene nitriles with 3‐azido‐2‐substituted thiophenes. Thus, for example the 3‐carboxy derivative 5 was prepared by condensation of 3‐azido‐2‐formylthiophene dimethyl acetal ( 1 ) with ethyl cyanoacetate, followed by intramolecular cyclization. Decarboxylation of 5 led to the unsubstituted parent compound 6 . The structure of the triazole‐fused compounds is discussed.