Rh(III)-Catalyzed Imidoyl C–H Carbamylation and Cyclization to Bicyclic [1,3,5]Triazinones

A Rh­(III)-catalyzed synthesis of bicyclic [1,3,5]­triazinones from a diverse array of imines coupled with ethyl (pivaloyloxy)­carbamate is reported. The preparation of [5,6]- and [6,6]-bicyclic heterocycles substituted with aryl, alkyl, and alkoxy groups demonstrated a broad reaction scope. The efficiency of this approach was further enhanced with the development of a three-component variant featuring in situ imine formation. X-ray crystallographic characterization of a rhodacycle formed by imidoyl C–H activation provides support for the proposed mechanism.