Synthesis of condensed bicyclic thiophene derivatives from diyne systems

Metallation of the acetylenes MeCCR (R = CC–SiMe3, CCMe, CC–Sme, CC–Nalkyl2, S–CCSiMe3, S–CC–Me) with BuLi·ButOK, followed by the successive addition of carbon disulphide, t-butyl alcohol, and hexamethylphosphoric triamide gives thieno[2,3,-b]thiophene, thieno-1,4-dithi-ine, and some of their derivatives in reasonable yields.