TfNH-catalyzed formal [3 + 2] cycloaddition of oxadiazolones with ynamides: a simple access to aminoimidazoles.

Oxadiazolones are first employed as the three-atom coupling partners in the TfNH-catalyzed cycloaddition with ynamides. This formal [3 + 2] cycloaddition allows a rapid synthesis of aminoimidazoles with a broad substrate scope. The approach also features a metal-free catalytic cycloaddition process, which may find applications in the synthesis of bioactive molecules. Besides, the resulting N-methyl products can further be readily converted to free N-H aminoimidazoles.