Facile synthesis of 1,3,6-oxadiazepines from 2,2′-(1,2-ethanediyldiimino)bisphenols

A useful sequence of reactions for the syntheses of a variety of heterocyclic systems including an oxadiazepine ring is described. The key step involves the condensation of substituted 2,2′-(1,2-ethanediyldiimino)bisphenols with ethanedial to provide stereoselectively the 6a,7a-trans-6,6a,7a,8,15,16-hexahydro[1,4]benzoxazine[4′,3′:6,7][1,3,6]oxadiazepino[2,3-c][1,4]-benzoxazine-6,8-diol framework, as established by X-ray diffraction analyses.