| Abstract
| - 2,3-Disubstituted benzo[b]thiophenes have been prepared in excellent yields via coupling of terminalacetylenes with commercially available o-iodothioanisole in the presence of a palladium catalystand subsequent electrophilic cyclization of the resulting o-(1-alkynyl)thioanisole derivatives. I2,Br2, NBS, p-O2NC6H4SCl, and PhSeCl have been utilized as electrophiles. Aryl-, vinyl-, and alkyl-substituted terminal acetylenes undergo this coupling and cyclization to produce excellent yieldsof benzo[b]thiophenes. (Trimethylsilyl)acetylene also undergoes this coupling/cyclization processwith I2, NBS, and the sulfur and selenium electrophiles to afford the corresponding 2-(trimethylsilyl)benzo[b]thiophenes. However, cyclization of the silyl-containing thioanisole using Br2 affords 2,3-dibromobenzo[b]thiophene.
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