An effective approach to azirino-fused heterocycles is disclosed. The approach, involving formation of heterocycle/C-(arylchloromethyl)-subsituted CN double bond via domino isomerization of a gem-dichloroaziridine-intramolecular Friedel-Crafts acylation of the O-tethered benzene ring and subsequent intramolecular cyclization induced by hydride, was realized for 1-aryl-1,11b-dihydroazirino[1,2-d]dibenz[b,f][1,4]oxazepines. The latter are excellent precursors of azomethine ylides, especially in solvent-free conditions, which can undergo a completely stereoselective 1,3-dipolar cycloaddition to CC dipolarophiles giving derivatives of dibenzo[b,f]pyrrolo[1,2-d][1,4]oxazepine.