Indole , with acetic acid spectrum

Early work had shown cinchonamine to give color reactions typical of indole alkaloids (7), and this was also evident from its UV-spectrum (8). The base differs from the major cinchona alkaloids in yielding, upon oxidation with chromic acid (6), 3-vinylquinuclidine-8-carboxylic acid (III), mp 209°, [a]D — 29° (CHCI3), which was first obtained from quinamine (9). The nature of the remainder of the molecule followed from the conversion of cinchonamine into 0,iVb-diacetylallocinchon-amine (I), mp 159°, [a]D — 7° (CHCI3), by refluxing acetic anhydride and its subsequent oxidation to 3-/3-acetoxyethylindole-2-aldehyde (H) (6). 

As well as ebumamine (282), the -oxide of 1,2-dehydroaspidosper-midine (281) gave a new product on reaction with triphenylphosphine and acetic acid (167). The compound showed a molecular ion at m/e 296 analyzing for C19H24N2O. The UV spectrum was that of an -acylindoline and the IR spectrum indicated a lactam (rmax 1680 cm-1). The product was unaffected by catalytic hydrogenation or by sodium cyanoborohydride reduction. In aqueous hydrochloric acid for 2 hr at 90°, the product was transformed into an -acylindole which was assigned structure 291. The parent compound for these transformations was therefore 292. Lithium aluminum hydride reduction of 292 gave the diamine 293, which afforded the indole 294 on treatment with acid. 

Lochnerinine (LXXXIX) was shown to be an aromatic methoxy-lochnericine by the 30 mass unit shift of the indolic peaks in its mass spectrum as compared with those of lochnericine 22). Reduction with zinc and acetic acid gave a dihydroindole whose UV-spectrum was closest to that of 7 -methoxyhexahydrocarbazole and the methoxy group was therefore placed at the 16-position 21, 22). Lochnerinine is the epoxide of 16-methoxy-( — )-tabersonine with which it co-occurs in Vinca herbacea 22a). 

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