reaction of uridyl aldehyde 19 with an amide-stabilized sulfur ylide. Two different strategies were shown to be efficient in constructing the diazepanone ringsystem: (a) a reductive amination of an epoxy aldehyde with N-methylamine with subsequent intramolecular oxirane ring opening and (b) a carbeneinsertionreaction of an acyclic diazoamine precursor.