Benzoxocin, benzoxepin and benzofuran frameworks from 5-glyco-4-nitrocyclohex-1-enes through Nef reaction and intramolecular cyclization

By treatment of sodium nitronate salts of 5-glyco-4-nitrocyclohexenes with hydrochloric acid, five new bicyclic ethers with six-membered rings fused to five-, seven-, or eight-membered rings have been synthesized; also a mechanism for their formation is proposed. Structural elucidation of the new compounds is based on spectroscopic data, as well as on their comparison with those of closely related substances.