Synthesis of N−H Bearing Imidazolidinones and Dihydroimidazolones Using Aza‐Heck Cyclizations

Abstract The synthesis of unsaturated, unprotected imidazolidinones via an aza‐Heck reaction is described. This palladium‐catalyzed process allows for the cyclization of N ‐phenoxy ureas onto pendant alkenes. The reaction has broad functional group tolerance, can be applied to complex ring topologies, and can be used to directly prepare mono‐ and bis‐unprotected imidazolidinones. By addition of Bu 4 NI, dihydroimidazolones can be accessed from the same starting materials. Improved conditions for preparing unsaturated, unprotected lactams are also reported.