Synthesis of tetrahydro-3-benzazepines

A synthetic route toward tetrahdro-3-benzazepines 1a–f starting with 2a and 2b in modest total yield is described. The facile route was carried by Henry reaction of aldehydes 3a–e with nitroalkanes and NH4OAc at reflux, reduction of the resulting nitroalkenes 4a–h with LAH at rt followed by protection with K2CO3 and PhSO2Cl at rt, one-pot oxidative cleavage annulation of olefins 5a–h with the one-pot combination of OsO4/NaIO4 at reflux, and hydrogenation of the corresponding enamines 6a–f. Aldehydes 3a–e was prepared from 2a and 2b in moderate yield of three-step.