An Efficient Approach to the [1,2,4]-Triazolo[3,2-d][1,5]Benzoxazepine Skeleton-A Novel Tricyclic Ring System

Abstract

Unprecedented [1,2,4]-Triazolo[3,2-d][1,5]benzoxazepine skeleton was easily achieved by cycloaddition of the allene-like cations 3, derived from 4-chromanone arylhydrazones, to the triple bond of nitriles and ensuing ring enlargement. The structural assignment of one product (5d) has been ultimately accomplished by X-ray diffraction analysis.