Regioselective Base-Mediated Cyclizations of Mono‑N‑acylpropargylguanidines

A regioselective base-mediated cyclization of mono-N-acylpropargylguanidines is reported. A related Ag­(I)-catalyzed hydroamination strategy was recently employed to yield N3-Cbz-protected ene-guanidines, which found utility in the synthesis of naamidine A. Herein, we report the base-catalyzed hydroamination of mono-N-acylpropargylguanidines, which proceeds with the opposite regiochemistry to deliver isomerized N2-acyl-2-aminoimidazoles with broad substrate scope, circumventing the problematic regiospecific acylation of free 2-aminoimidazoles.