The Alkaloids of Tylophora asthmatica

Tylophorinine was purified (12) by rechromatography over alumina and converted to a hydrochloride which was subjected to repeated crystallization from ethanol. The base regenerated from the pure hydrochloride melted at 248°-249° after recrystallization from chloroform and had [a]j — 14.2° (c 1.76, CHCI3). Careful analysis of the base and its salts resulted in the revision of the molecular formula of tylophorinine to C23H25O4N. 

Tylophorine, C24H27O4N (IV), is a tertiary base having four methoxyl groups but no V-methyl group and no easily reducible unsaturation. Its UV-spectrum has maxima at 255, 290, 340, and 352 my (loge 4.74, 4.49, 3.30, 2.93) indicating the presence of a phenanthrene chromophore. 

Treatment of tylophorine with cyanogen bromide yields a crystalline bromocyanamide, which on treatment with sodium borohydride yields a hydroxycyanamide. The latter on hydrolysis with sulfuric acid yields tylophorine, indicating the presence of a 1 4 or 1 5 amino-alcohol system in the compound. 

Oxidation of the Hofmann degradation product from isodihydrohomotylophorine yields a mixture of acidic products. These can be converted to the corresponding methyl esters and then separated by chromatography into a mono ester, C21H22O6 (mp 185°-186°), and a 

On the basis of these degradation studies tylophorine is formulated as 9,Il,12,13,13a,14-hexahydro-2,3,6,7-tetramethoxy-dibenzo[/,A.]pyrrolo-[ 1,2-6]isoquinoline (IV). The structures of tylophorinemethine, de-iV -methyltylophorinemethine, isodihydrohomotylophorine, and detetra- 

---