Organocatalytic Diastereoselective Synthesis of Diazoaryl-benzo[b]azepine Derivatives.

To construct multisubstituted seven-membered nitrogenous heterocyclic scaffolds, an efficient method, employing 2-aminoaryl N-monosubstituted hydrazones and 2-oxo-3-butenoates under Brønsted acid catalysis, has been developed. This strategy highlights the umpolung reactivity of 2-aminobenzaldehyde arylhydrazones toward 2-oxo-3-butenoates to afford (E)-diazoaryl-benzo[b]azepine derivatives in excellent yields (89-99%) and with high diastereoselectivities (>19:1 dr).