Ligand-free copper-catalyzed efficient one-pot access of benzo[b]pyrido[3,2-f][1,4]oxazepinones through O-heteroarylation-Smiles rearrangement-cyclization cascade

Efficient synthesis of a library of novel benzopyrido[1,4]oxazepinones was accomplished by Cs2CO3-mediated one-pot coupling of N-substituted-o-chloronicotinamides and o-halogenated phenols using cuprous oxide catalysis in DMF at 120 degrees C through an O-heteroarylation-Smiles rearrangement-cyclization cascade (16 examples). The C-N bond construction process is biased in favour of Smiles rearrangement allowing regioselective generation of these tricyclic molecular architectures essentially free from Goldberg-N-arylation products in good to excellent yields.