Synthesis of thieno[2,3-b]thiophene fused pyrimidine derivatives via sequential conversion of 3,4-diaminothieno[2,3-b]thiophene-2,5-dicarbonitrile with carbonyl compounds

Symmetric pyrimidine, pyridine fused thieno[2,3-b]thiophene or their cross-fused thieno[2,3-b]thiophene compounds were synthesized by the cyclocondensation of symmetric thieno[2,3-b]thiophene o-aminonitrile with carbonyl compounds based on the different catalytic conditions.