Oxidation of .beta.-anilinoacrylate alkaloids vincadifformine and tabersonine by Fremy's salt. A mechanistic insight into the rearrangement of Aspidosperma to Hunteria eburnea alkaloids
Synthesis of vinca alakaloids and realated compounds<b>98</b>. Oxidation with dimethyldioxirane of compounds containing the aspidospermane and quebrachamine ring system. A simple synthesis of (7<i>S</i>,20<i>S</i>)-(+)-rhazidigenine and (2<i>R</i>,7<i>S</i>,20<i>S</i>)-(+)-rhazidine
The oxidation of (-)-tabersonine (1) with dimethyldioxirane (DMD) in neutral and acidic medium gave 16-hydroxytabersonine-N-oxide (3) and the didehydrovincamine isomers 4 and 5, respectively. (+)-14,15-Didehydro-quebrachamine (7) furnished the hydroxyindolenine 9, and the pentacyclic derivative 11. (+)-Quebrachamine (8) and DMD in neutral medium gave (7S,20S)-(+)-rhazidigenine (12) which was converted
Chemical transformations started from tabersonine were studied. A one-pot oxidative ring-transformation with permaleic acid in methanol yielded 17,18-dehydrovincamine. Hydroboration-oxidation of the latter compound led to alkaloid 17,18-dehydrovincamone. Hydroboration-oxidation of tabersonine resulted 14 beta-hydroxyvineadifformine and 15p-hydroxyvincadifforinine. Allowing 14 beta- and 15 beta- hydroxyvincadifformines to react with permaleic acid/methanol provided 1,14-secovincamines, serving as new evidence for the mechanism of the aspidospermane-eburnane transformation. On the other hand 18 beta-hydroxyvincamine was obtained from 14 beta-hydroxyvincadifformine by reaction with 3-chloroperbenzoic acid and successive treatment with triphenylphosphine/aqueous acetic acid.
Calabi, Luisella; Danieli, Bruno; Lesma, Giordano, Journal of the Chemical Society. Perkin transactions I, 1982, p. 1371 - 1380
作者:Calabi, Luisella、Danieli, Bruno、Lesma, Giordano、Palmisano, Giovanni