Synthesis of condensed bicyclic thiophene derivatives from diyne systems

Abstract

Metallation of the acetylenes MeCCR (R = CC–SiMe₃, CCMe, CC–Sme, CC–Nalkyl₂, S–CCSiMe₃, S–CC–Me) with BuLi·Bu^tOK, 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.