The xanthate radical addition route to sulfur heterocycles

This account summarizes the application of the degenerative addition-fragmentation of xanthates for the synthesis of various sulfur heterocycles. Many of the structures obtained in this manner are difficult or tedious to obtain by more conventional routes. These include γ-thiolactones, tetrahydrothiophenes, dihydrothiophenes, thiophenes, dithiospiroketals, 1,3-dithian-2-ones, 1,2-dithiolanes, 1,3-dithiolan-2-ones, benzothiepinones, 2,3-dihydrothieno[2,3-b]thiopyran-4-ones, dihydrothiazines, difluorothiochromanes, and 1,3-dithietan-2-ones. The mechanistic rationales and occasional serendipitous observations undergirding these methods are discussed briefly.