Chemical examination of Tylophora asthmatica—V Structure of tylophorinine

Tylophorinine, the minor alkaloid of Tylophora asthmatica, has been oxidized to yield 2,3,6-trimethoxyphenanthrene-9,10-dicarboxylic acid. A synthesis of the corresponding imide has been achieved. Desoxytylophorinine, obtained by hydrogenolysis of the alkaloid, has been synthesized. These results in conjunction with other degradation experiments have enabled the assignment of the structure XIV to tylophorinine.