Synthesis of 3,5-Diamino-Substituted Dithieno[3,2-b:2′,3′-d]thiophene Derivatives

We report the first synthesis of 3,5-diamino-substituted dithieno[3,2-b:2′,3′-d]thiophene derivatives, bearing alkoxycarbonyl or acetyl groups at C-2 and C-6 positions. The target compounds were prepared via the reaction of 3,4-dibromothiophene-2,5-dicarbonitrile with alkyl thioglycolates or mercaptoacetone in the presence of DBU and isolated in 67–87% yield. The key dinitrile was synthesized in 76% yield from 3,4-dibromothiophene-2,5-dicarbaldehyde. In turn, this dialdehyde was prepared on a multigram scale from commercially available 2,5-dimethylthiophene in three steps. The resulting dithieno[3,2-b:2′,3′-d]thiophenes serve as valuable building blocks for materials chemistry, offering multiple reactive sites for further structural elaboration and property tuning.