An S(N)2-like transition state for alkene episulfidation by dinitrogen sulfide

Episulfidation of alkenes by dinitrogen sulfide, generated from thermolysis of 5-aryloxy-1,2,3,4-thiatriazoles, was found to be an S(N)2-like reaction involving simultaneous sulfur addition and dinitrogen extrusion. The preference for the one-step S(N)2 mechanism instead of the two-step (2+3) dipolar cycloaddition and denitrogenation is attributed to the higher geometry distortion penalty in the (2+3) transition state than that in the S(N)2-like transition state.