Efficient Synthesis of 2,3-Disubstituted Benzo[b]thiophenes Starting from 2-Aminobenzophenone

Abstract

Benzo[b]thiophene derivatives have been reported to have many interesting biologically properties and the synthesis and derivatization of the benzo[b]thiophene ring have drawn much interests. The syntheses of the benzo[b]thiophene ring were usually accomplished by the formation of a fused thiophene ring starting from appropriate benzene derivatives through the formation of one bond ‘a’, ‘b’, ‘c’, or ‘d’, or the formation of two bonds ‘a’ and ‘b’, ‘a’ and ‘c’, or ‘b’ and ‘c’. The fused thiophene ring synthesis through the formation of ‘b’ and ‘c’ bonds would readily provide 2,3disubstituted benzo[b]thiophene derivatives. For the thiophene ring synthesis through that two-bond formation, 2mercaptobenzoyl derivatives 1 or their precursor compounds are necessary as starting materials. However, only a few 2mercaptobenzoyl derivatives or their precursors are readily available.