Gelsedine

In a recent investigation Wenkert et al. (104) have shown that gelsedine (XLI) is 11-demethoxygelsemicine. The facile elimination of the A7-methoxyl group has been confirmed, since it can also be removed by means of lithium in liquid ammonia or by sodium and butanol. The demethoxygelsedine so obtained gives an A7b-acetyl derivative (XLII), which exhibits IR-absorption at 3413 cm-1. This absorption cannot be 

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The minor alkaloid gelsedine, originally isolated from G. sempervirens in 1953 (3), has also been found in G. elegans (19). The structure of gelsedine (6) has been determined by means of H-NMR and mass spectral analysis (4,9)... 

It is interesting that the H-NMR data of the dihydro derivative (34) are practically identical with those of 14/1-hydroxygelsedine (8) which was isolated from G. sempervirens in 1985 (11), although the latter data were, recorded at 360 MHz while the former at 90 MHz in the same solvent (CDC13). Since humantenidine has been proved to be 14-hydroxy-A4,20-gelsedine, it appears that 34 and 8 are the same material. 

Hiemstra and co-workers reported the first example of an iodine-promoted allenyl N-acyliminium ion cyclization for the total synthesis of (+)-gelsedine, the enantiomer of the naturally occurring (-)-gelsedine [72], Compound 341 was prepared from (S)-malic acid. When 341 was dissolved in formic acid with a large excess of Nal and heated at 85 °C for 18 h, 343 was found to be the major product isolated in 42% yield. The latter was then successfully converted to (+)-gelsedine in a multi-step manner. Other routes without the allene moiety failed to provide the desired stereoisomer. The successful one-step transformation of 341 to 343 was key to the success of this synthesis. 

N.A. Gelsemine, gelsedine, iridoids, coumarins, tannins." This herb is toxic. A sedative, antispasmodic, treat neuralgia, facial nerve pain. Externally treat intercostal neuralgia. 

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