LiBr-Catalyzed C3-Disulfuration between Indole and N -Dithiophthalimide.

A simple, green halide-catalyzed protocol for disulfuration of indole derivatives with N -dithiophthalimides has been developed. This C-H disulfide reaction proceeded smoothly at room temperature with economical LiBr as catalyst, providing an effective method for the synthesis of novel unsymmetrical disulfides. A series of 3-dithioindole derivatives were obtained in high yields with good functional group tolerance; moreover, the wide scope of Harpp reagents (aryl, benzyl, primary, secondary, tertiary) confirmed the practicability of this approach.