Alkaloids of Delphinium corumbosum
SummaryFromDelphinium corumbosum Rgl. have been isolated methyllycaconitine, a new base which has been called delcorine, and a base with mp 93–95°C. On the basis of its chemical and spectral characteristics, a lycoctonine skeleton has been established for delcorine with α-hydroxy groups at C1 and C10, a β-hydroxy group at C6, a methylenedioxy group at C7 and C8, a β-methoxy group at C15, and a methoxy group at C19.
THE PARTIAL STRUCTURES OF ACONITINE AND ACONITOLINE
In aconitoline (C33H41O10N), the product of the oxidation of aconitine with chromic acid, the presence of an αβ-unsaturated carbonyl group has been confirmed. The determination of the basic strengths of aconitoline and its various hydrolytic and reduction products revealed a very strong influence of the carbonyl on the basicity of the alkaloid. It was concluded that the secondary hydroxyl that becomes oxidized must be located in close proximity to the nitrogen. Partial structures are suggested to represent both aconitine and aconitoline.
A suggested structure for delsoline
The alkaloid delsoline (C25H41O7N) was oxidized by acid permanganate mostly to dehydrooxodelsoline, and by neutral permanganate to anhydrohydroxydelsoline. Oxidation of the alkaloid with mercuric acetate produced anhydrohydroxy-N-de-ethyldelsoline which could be re-ethylated with ethyl iodide, thus showing the presence of an N-ethyl group in delsoline. Anhydrohydroxydelsoline was also obtained from O-acetyldelsoline perchlorate by oxidation to an anhydronium salt followed by hydrolysis with sodium hydroxide, and this method of preparation provides evidence of its carbinolamine structure. O-Acetyloxodelsoline, obtained from acetyldelsoline, is cleaved by lead tetra-acetate to a secodiketone that loses the elements of methanol on recrystallization. Hence the base contains two vicinal tertiary hydroxyls, one of which is β to a methoxyl group. Dehydrooxodelsoline is also cleaved by lead tetra-acetate and the product undergoes an internal aldol rearrangement. These results are interpreted in the light of a structure that is tentatively suggested for delsoline.