Synthesis of Isothiazole via the Rhodium-Catalyzed Transannulation of 1,2,3-Thiadiazoles with Nitriles

A synthetic method for obtaining a wide variety of isothiazoles by the Rh-catalyzed transannulation of 1,2,3-thiadiazoles with alkyl, aryl, and heteroaryl nitriles, which proceeds via an α-thiavinyl Rh-carbenoid intermediate, was developed. The results suggest that during its reaction with nitriles, the α-thiavinyl carbene acts as an umpolung 1,3-dipole equivalent, in contrast to its behavior during its reaction with alkynes. The developed method was successfully employed to synthesize pentaoligomeric arylene compounds consisting of three benzene and two isothiazole rings.本研究开发了一种合成方法，可通过铑（Rh）催化1,2,3-噻二唑与烷基、芳基及杂芳基腈的转环化反应，制备多种异噻唑类化合物，该反应经由α-硫代乙烯基铑卡宾中间体完成。研究结果显示，相较于该中间体与炔烃的反应模式，α-硫代乙烯基卡宾在与腈类反应时，可作为极性反转的1,3-偶极体等价物参与反应。所开发的方法已成功应用于合成由3个苯环与2个异噻唑环构成的五聚芳撑类化合物。