Trisulfur Radical Anion (S3•-)-Promoted Defluorotrisulfuration-Cyclization of Allylic gem-Difluoromethylenes with Elemental Sulfur through C-F and C-H Bond Functionalization.

A defluorotrisulfuration-cyclization reaction of allylic gem-difluoromethylenes with elemental sulfur via sequential C(sp3)-F and C(sp2)/C(sp3)-H bond functionalization has been developed for the synthesis of structurally significant 1,2-dithiole-3-thiones. The success of this transformation arises from the dual roles of sulfur: (1) acting as a commercially available, low-cost, nontoxic, bench-stable, and easy-to-handle sulfurating reagent that enables the construction of three C-S/C═S bonds under mild reaction conditions and (2) serving as a defluorinating promoter via in situ generation of a reactive trisulfur radical anion. Moreover, the distinct reactivity profiles of a series of allylic haloalkyl alkenes are first demonstrated. The one-pot synthesis of the anethole dithiolethione drug is achieved, and the resulting product can be transformed into high-value heterocycles.