Synthesis of sulfenyl dipyrroles via reaction of α-free pyrroles with thionyl chloride

Sulfenyl dipyrroles feature two pyrroles linked via a sulfenyl bridge. The synthesis of sulfenyl dipyrroles has typically involved SCl 2 as the sulfur source. However, SCl 2 is no longer readily available within North America and Europe. Herein we report a new synthesis of sulfenyl dipyrroles using SOCl 2 as the sulfur source and reductant. Although five new sulfenyl dipyrroles were synthesized and isolated via this route, functional group tolerance proved limited. A potential mechanism for the reaction, involving reduction of a sulfinyl moiety by SOCl 2 , is briefly explored.