Synthesis of C2 Substituted Benzothiophenes via an Interrupted Pummerer/[3,3]-Sigmatropic/1,2-Migration Cascade of Benzothiophene S-Oxides
Synthesis of C2 Substituted Benzothiophenes via an Interrupted Pummerer/[3,3]-Sigmatropic/1,2-Migration Cascade of Benzothiophene S-Oxides
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DOI：
10.1002/anie.201801982
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发表时间：
2018-05-14
影响因子：
16.6
通讯作者：
Procter, David J.
中科院分区：
文献类型：
--
作者：
He, Zhen;Shrives, Harry J.;Procter, David J.
功能化苯并噻吩类化合物是存在于具有广泛生物活性的分子和有机材料中的重要支架。我们描述了一种有效的、无金属的C2芳基化、烯丙基化和丙烯酰化苯并噻吩类化合物的合成方法。该反应以独特的级联顺序利用合成的未开发但容易获得的苯并噻吩氧化物和苯酚、烯丙基或炔丙基硅烷。苯并茂S氧化物与偶联对之间中断的Pummerer反应生成的硫盐缺乏芳香性，因此允许简单的[3，3]-Sigma重排。随后生成的苯并硫苯盐经历了先前未被探索的1，2-迁移，以获得C2功能化的苯并硫苯。
Functionalized benzothiophenes are important scaffolds found in molecules with wide ranging biological activity and in organic materials. We describe an efficient, metal-free synthesis of C2 arylated, allylated, and propargylated benzothiophenes. The reaction utilizes synthetically unexplored yet readily accessible benzothiophene S-oxides and phenols, allyl-, or propargyl silanes in a unique cascade sequence. An interrupted Pummerer reaction between benzothiophene S-oxides and the coupling partners yields sulfonium salts that lack aromaticity and therefore allow facile [3,3]-sigmatropic rearrangement. The subsequently generated benzothiophenium salts undergo a previously unexplored 1,2-migration to access C2 functionalized benzothiophenes.