Metal-free photoinduced hydrogen atom transfer assisted C(sp3)–H thioarylation

Abstract

C−H thioarylation of hydrocarbon building blocks is a highly desirable synthetic transformation because of its prevalence in various pharmaceuticals and organic functional materials. However, to date all the developments majorly rely on peroxide mediated transformations. Unfortunately, the harsh reaction conditions of these reactions cause severe functional group intolerance. To overcome these issues, photo-induced radical coupling reactions have gained significant attention as a sustainable solution, which require either metal based photosensitizers or the use of an organophotocatalyst. Herein, we demonstrate a mild metal-free approach for C(sp³)–H thioarylation using thioxanthone as a photo-catalyst. The protocol is compatible with various arenes, as well as unactivated alkanes and cycloalkanes. The post-synthetic modifications of thioarylated compounds are also demonstrated through cross-coupling reactions and functional group interconversions.