Direct conversion of sulfinamides to thiosulfonates without the use of additional redox agents under metal-free conditions.

Direct conversion of sulfinamides to thiosulfonates is described. Without the use of additional redox agents, the reaction proceeds smoothly in the presence of TFA under metal-free conditions. This protocol possesses many advantages such as odourless and stable starting materials, broad substrate scope, selective synthesis, and mild reaction conditions.

Switchable regioselection of C-H thiolation of indoles using different TMS counterions.

A switchable regioselectivity in C-H thiolation reaction by simply swapping the counteranions of TMS is reported here for the first time. An exclusive C3-H thiolation of indoles with sodium arylsulfinates was achieved in the presence of TMSCl as a promoter. In contrast, with the use of TMSOTf instead of TMSCl under otherwise identical conditions, a regiospecific C2-H thiolation of indoles was realized with the same set of substrates.

Regioselective and oxidant-free sulfinylation of indoles and pyrroles with sulfinamides.

An unexpected time-controlled highly selective C3- or C2-sulfinylation of pyrroles with sulfinamides is reported for the first time. The sulfinylation of indoles with sulfinamides using this protocol is oxidant-free and can be performed under obviously more feasible conditions (1.2 equiv. of indoles, 10 min) in comparison with the precedent procedure (3-20 equiv. of indoles, 16-18 h, ammonium persulfate as oxidant, hv). A variety of functional groups were tolerated, and various C2-thioindoles and C2/3-thiopyrroles were obtained in moderate to excellent yields.