Delcosine has been assigned tentatively the same C—N skeleton as lycoctonine. In lycoctonine, ring A carries at C-1 a methoxyl group which is directed away from the nitrogen ring. In delcosine, C-1 carries a hydroxyl group which has the opposite configuration and is directed towards the nitrogen. An attempt to correlate the two structures first involves epimerization at C-1 in delcosine. This has been carried out by oxidation of desethyldelcosine to an azomethine, the ethiodide of which, by the action of methanolic potassium hydroxide, is converted to oxo-1-epidelcosine in two steps. Oxo-1-epidelcosine in an acid-catalyzed rearrangement is transformed to a pinacone which, after methylation, gives O,O-dimethyl-anhydro-oxo-1-epidelcosine. This compound was compared with O-methylanhydro-oxolycoctonine, prepared from oxolycoctonine, but was not identical. Removal of a methoxyl, which in each compound is ortho to a carbonyl, by the action of sodium amalgam, produced O,O-dimethyl-6-desmethoxy-anhydro-oxo-1-epidelcosine and O-methyl-6-desmethoxy-anhydro-oxolycoctonine, which are not identical, but show in their infrared spectra much less dissimilarity than the spectra of the pair of compounds from which they were derived. These results are discussed in terms of the structure of delcosine.
