N-Heterocyclic carbene catalyzed dehydrogenative coupling of enals: synthesis of monobactams

The first NHC-catalyzed dehydrogenative coupling of enals is described. With a suitable combination of NHC precatalyst, base, and solvent, the reaction proceeded smoothly to yield a wide range of monobactams. These substituted monobactams have been synthesized for the first time, and they are versatile synthetic intermediates toward other useful complex molecules.