The alkaloids of Gelsemium sempervirens. Part IV. Derivatives of pyridine, isoquinoline, and indol-2(3H)-one as possible initial materials for synthesis of gelsemine

Derivatives of pyridine-3,4-dicarboxylic acid, of 1,3-dioxodecahydroisoquinoline-4-carbonitrile, of 3-cyclopentylindol-2(3H)-one, and of spiro[cyclohexane-1,3′-indole]-2′(3′H)-one and the derived decahydrospiro-[indole-3,7′-isoquinoline]-2(3H)-one, are described.