43 生合成モデルとしての光化学反応 : オレアナン系トリテルペンを中心として

概要

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Interested in photochemical reactions being applied in the biogenetic type chemical derivation of natural products, we have investigated the photochemical transformation of some triterpenoids. It has been clarified that the photooxidation of oleanolic acid (I) in an acidic medium afforded 12α-hydroxy- and 11α,12α-epoxy-oleanolic lactones (VIIIa, VIIa), the latter having the identical epoxy-lactone moiety with eupteleogenin (II), while the similar oxidation of erythrodiol (XVIIIa) yielded 11α,12α:13β,28-diepoxy compound (XIXa) in addition to 11α,12α-epoxy-taraxerol derivative (XXa). Some interesting features found during the course of the study on the above photoreaction products have been discussed, and in addition, priverogenin B (XXVIb), a genuine sapogenin of Primula sp., has been derived from camelliagenin A (XXIb). Furthermore, the photolytic decarboxylation of leucotylic acid derivatives (XXVII) has been investigated as a model experiment leading to the exo-methylene compounds (XXVIII). Finally, it has been suggested being possible to synthesize eupteleogenin (II) partially in a few steps, following the above-developed photoreactions, starting from e.g. spergulagenic acid (XXIX).
天然有機化合物討論会の論文
1968-09-20