Base-mediated regioselective [3+2] annulation of ketenimines and isocyanides: efficient synthesis of 1,4,5-trisubstituted imidazoles.

A novel base-mediated regioselective [3+2] annulation of active methylene isocyanides with ketenimines has been developed. In the presence of t-BuOK, a wide range of ketenimines readily react with active methylene isocyanides in DMF at 40 °C to afford 1,4,5-trisubstituted imidazoles efficiently.