Chemo‐ and Regioselective C−H Sulfidation of Indoles for the Synthesis of Tolylthioindoles under Metal‐Free Conditions

Controllable chemoselectivity and regioselectivity synthesis of 3-sulfinylated, 3-sulfenylated and 2-sulfonylated indoles via direct C-H functionalization are realized under metal-free conditions. In particular, the synthesis of 3-arylsulfinylindoles in high yields from a sulfone substrate in water without additives is reported. The process displays excellent functional groups compatibility. p-Toluenesulfonyl cyanide (TsCN) possess a hexavalent sulfonyl group, as an odorless and easy-to-handle solid, which has been used as a new sulfur reagent through the cleavage of S-C and S=O bonds in our work.