Synthesis of symmetrically substituted bis-TTF fused 1,4-dithiine (BTDT) derivatives

To prepare the title compounds which show bent molecular shapes at the centers, a general synthetic route is developed. The successive treataent of 4,5-Vinylenedithio-1,3-dithiole-2-thione (5) with LDA, sulfur and thiophosgene gave the key intenediate of the dithione (6). The thiocarbonyl groups were oxidized to carbonyl groups by Hg(OAc)2. The coupling reaction of this diketone(7) and 4,5-bis(aethylthio)-1,3-dithiole-2-thione (10) gave (MeS)4BTDT (1, R1 = R2 =SCH3) as the first example utilizing our synthetic strategy.