Electrocatalytic Desulfurizative Amination of Thioureas to Guanidines

Abstract

Guanidine has been known as an important class of N-containing molecules with a wide range of applications. Described here is a selective and efficient electrochemical approach to the synthesis of guanidines from easily accessible thioureas and amines. The key to success for this reaction is the in situ generation of a hypervalent iodine reagent as a catalyst from iodoarene by anodic oxidation. This mild desulfurizative amination presents ample substrate scope and good functional group tolerance without the use of extra stoichiometric chemical oxidants. As only electrons serve as the oxidation reagents, this method offers a more straightforward and sustainable manner toward versatile guanidines, including late-stage functionalization of pharmaceutically relevant molecules.

Electrochemical Desulfurizative Amination of Heteroaromatic Thiols by Iodine Catalysis

“…Then the sulfur atom of thiourea Int-2 attacks on the electrophilic iodine (III) of o-iodosobenzoic acid species, which is generated by anodic oxidation of 2-iodobenzoic acid I-1 catalyst, to afford the λ 3 -iodane intermediate Int-3. [18] Finally, intramolecular cyzliation and reductive elimination of Int-3 with the expulsion of sulfur produces the desired amination product and regenerates I-1. Alternatively, this electrooxidative desulfurization also give the desired product in moderate yield (60 %) in the absence of an iodoarene catalyst.…”