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

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(sp(3))-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.

Automated summary

C-H thioarylation of hydrocarbon building blocks is a highly desirable synthetic transformation due to its prevalence in pharmaceuticals and organic functional materials. However, current developments rely on peroxide mediated transformations which have drawbacks of harsh reaction conditions and functional group intolerance. This study demonstrates a mild metal-free approach for C(sp(3))-H thioarylation using thioxanthone as a photo-catalyst, showing compatibility with various arenes, unactivated alkanes, and cycloalkanes. Post-synthetic modifications are also demonstrated through cross-coupling reactions and functional group interconversions.