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

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.