Synthesis of benzo[b]thiophenes by electrophilic cyclization

2,3-Disubstituted benzo[b]thiophenes are readily prepared in excellent yields under very mild reaction conditions by the Pd Cu-catalyzed cross-coupling of commercially available o-iodothioanisole a-nd terminal alkynes, followed by electrophilic cyclization Gy I-2, Br-2, NBS, p-O2NC6H4SCl or PhSeCl. (C) 2001 Published by ElseNier Science Ltd.