An Expedient Procedure for the Synthesis of Benzo[4,5]silolo[2,3-b]thiophenes and Related Systems

Abstract

The straightforward assembly of various thiophene-fused benzosiloles is accomplished by 2-fold metalation of benzo[b]thiophenes substituted at C3 with ortho-brominated aryl groups followed by electrophilic substitution with dichlorosilanes. The method relies on the innate acidity of the C(sp2)–H bond at C2 of benzo[b]thiophenes and the halogen–metal exchange of the proximal C(sp2)–Br bond. The related indole- and benzofuran-annulated systems are also accessible, but these siloles are chemically less stable. An example of a thiophene-fused benzogermole is included as well.