Synthesis of new thieno[2,3‐d]pyrimidines,thieno[3,2‐e]pyridines,and thieno[2,3‐d][1,3]oxazines

o‐Aminothiophene dicarbonitrile 1 on neat reaction with cyclic ketones in anhydrous ZnCl₂ yielded mixture of fused aminopyridine 3 and iminospirooxazine 4 derivatives. Similarly, pyrimidine derivatives 5 and 8 were obtained by the reaction of this intermediate 1 with formic acid and DMF‐DMA followed by hydrazine hydrate, respectively. The reaction of o‐amino‐thiophene dicarboxamide 2 at ambient temperature with cyclic ketones yielded spiropyrimidine 10 as a sole product in quantitative yield. The regioselective anellated pyrimidine 9 , 11 , and dihydropyrimidine 12 derivatives were also obtained by the reaction with aromatic aldehydes in presence of piperidine and iodine respectively. J. Heterocyclic Chem., (2012).