A versatile and efficient synthesis of bithiophene-based dicarboxaldehydes from a common synthonElectronic supplementary information (ESI) available: Experimental details, and spectroscopy. CCDC 945046, 945047 and 945048. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ob01135c

Bithiophene dicarboxaldehydes are promising electron-rich building blocks for the development of arylene vinylene-based organic semiconductors, but their use has been limited due to their synthetic inaccessibility. To facilitate the facile synthesis of these compounds we have prepared a novel functional bithiophene, namely 2,2′-(3,3′-dibromo-[2,2′-bithiophene]-5,5′-diyl)bis(5,5-dimethyl-1,3-dioxane) in two high yielding steps from 3,3′,5,5′-tetrabromo-2,2′-bithiophene. This synthon is readily transformed into variety of bithiophene-based dicarboxaldehydes, also in high yields. The use of these functional molecules in the synthesis of arylene vinylene-linked donor-acceptor copolymers is demonstrated by the synthesis of two copolymers with electron deficient benzobisazoles. The efficient synthesis of several bithiophene dialdehydes from a common intermediate is reported.