Yue Dawei, Larock Richard C
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
J Org Chem. 2002 Mar 22;67(6):1905-9. doi: 10.1021/jo011016q.
2,3-Disubstituted benzo[b]thiophenes have been prepared in excellent yields via coupling of terminal acetylenes with commercially available o-iodothioanisole in the presence of a palladium catalyst and subsequent electrophilic cyclization of the resulting o-(1-alkynyl)thioanisole derivatives. I(2), Br(2), NBS, p-O(2)NC(6)H(4)SCl, and PhSeCl have been utilized as electrophiles. Aryl-, vinyl-, and alkyl-substituted terminal acetylenes undergo this coupling and cyclization to produce excellent yields of benzo[b]thiophenes. (Trimethylsilyl)acetylene also undergoes this coupling/cyclization process with I(2), NBS, and the sulfur and selenium electrophiles to afford the corresponding 2-(trimethylsilyl)benzo[b]thiophenes. However, cyclization of the silyl-containing thioanisole using Br(2) affords 2,3-dibromobenzo[b]thiophene.
在钯催化剂存在下，通过末端乙炔与市售的邻碘硫代苯甲醚偶联，然后将所得的邻（1-炔基）硫代苯甲醚衍生物进行亲电环化反应，已以优异的产率制备了2,3-二取代苯并[b]噻吩。碘（I₂）、溴（Br₂）、N-溴代琥珀酰亚胺（NBS）、对硝基苯硫氯（p-O₂NC₆H₄SCl）和苯基硒氯（PhSeCl）已被用作亲电试剂。芳基、乙烯基和烷基取代的末端乙炔可进行这种偶联和环化反应，以高产率生成苯并[b]噻吩。（三甲基甲硅烷基）乙炔也可与碘（I₂）、N-溴代琥珀酰亚胺（NBS）以及硫和硒亲电试剂进行这种偶联/环化反应，得到相应的2-（三甲基甲硅烷基）苯并[b]噻吩。然而，使用溴（Br₂）使含甲硅烷基的硫代苯甲醚环化会得到2,3-二溴苯并[b]噻吩。
