A biomimetic synthesis of a new skeletal Gelsemium alkaloid, 11-methoxy-19(R)-hydroxygelselegine
✍ Scribed by Hiromitsu Takayama; Mariko Kitajima; Shin-ichiro Sakai
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- French
- Weight
- 605 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Based on a suggested biogenetic sequence, a sarpagine-type indole alkaloid, gardnerine (21, was stereoselectively converted to a new skeletal type Gelsemium alkaloid, ll-methoxy-19(R)_hydroxygelselegine (I), via a biogenetically hypothetical axiridine intermediate (17). Biomimetic synthesis (or biogenetic-type synthesis) has been employed as one of the useful strategies for natural product synthesis, because this method has enabled one to attain overall efficiency of the synthetic scheme and to evaluate the mechanistic validity of a key step in the hypothetical biogenetic route. More than forty monoterpenoid indole alkaloids including six skeletal types have been isolated from the Gdsemium plants (LoganiaceaeJl and their plausible biogenetic route was proposed based on the relationship of the chemical structures of the emerged alkaloids. la.2 Up to now, many kinds of Gelsemium alkaloids belonging to the sarpagine-,8 koumine-,4 humantenine-,5 and gelsedine-groups8 were synthesized in a biomimetic manner based on the suggested biogenetic sequence. In 1990, Cordell et al. found a new skeletal type of Gelsemium alkaloid, 11-methoxy-19(R)hydroxygelselegine (l), from G. elegans Benth., 7 the original plants of Chinese traditional medicine "Kou-Wen".lb We have planned the synthesis of this structurally unique alkaloid, whose C21 carbon is rearranged to the ezo position of the D-ring in the common monoterpenoid indole alkaloids.
Gardnerhe 2