Condensation reactions of 3-amino-4-imino-4H-thieno-[3,4-c][1]benzopyran

The title compound 1 reacts with trifluoroacetic anhydride to give the doubly trifluoracetylated derivative 2 and in addition the coumarin derivative 3. In refluxing DME two moles of 1 react with loss of one molecule of ammonia to afford 4, which undergoes subsequent N-acylation by beta-dicarbonyl compounds 9a-f to yield N-acyl derivatives 10a-f. With dimethyl malonate (9a) besides compound 10a, the cycloacylated compound 11 was also obtained in good yield. Compound 11 is readily hydrolysed and decarboxylated with both acid and alkali to the previously described fused derivative 12. The latter may be converted into the new thienopyrimidinone derivative by action of aqueous alkali.