Base-Promoted Three-Component N-Thiocarbamidation of Amines: Access to Unsymmetrical Thioureas via EDA Complexes

Abstract

Novel, redox-neutral, and base-promoted N-thiocarbamidation of amines has been developed for the efficient synthesis of unsymmetrical thioureas. Various imines and secondary amines are demonstrated to be compatible with this reaction system. Mechanistic investigations have unambiguously established that the transformation proceeds via a radical pathway, initiated by an intracomplex single-electron transfer process within a photoexcited electron donor–acceptor (EDA) complex. This key intermediate is formed through the in situ generated dithiocarbamate anions─produced by the reaction of amines with CS2 under basic conditions─with imines.