Reduction of thebaine with lithium aluminium hydride–aluminium chloride mixtures gives either thebainone-A enol methyl ether or neodihydrothebaine as the major product, depending on the ratio used. A novel product, isometathebainone enol methyl ether, has been isolated from the reduction with aluminium hydride, and its structure has been confirmed by conversion into dihydrometathebainone.