5 わらびの発癌物質プタキロサイドの合成研究(口頭発表の部)

概要

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Synthesis of (±)-ptaquilosin (2), the aglycon of ptaquiloside (1) a carcinogenic substance of bracken fern is described. δ-valerolactone (3) was converted by seven-step sequence into a bromo ketone (5c), the intramolecular alkylation of which afforded a cis-hydrindane compound (6). A cyclopropyl unit was constructed in the compound (6) to give a ketone (7a). The hydroxy group was introduced into a cyclopentane moiety of ketone (7a) by following sequence: 7a→12→13→14. Highly stereoselective addition of a Grignard reagent to the ketone (14) followed by Swern oxidation of the resulting diol (15a) afforded a ketone (16), which was methylated by the Kuwajima's method to provide a compound (17a). The compound (17a) was converted into an aldehyde (20). Introduction of a hydroxy group at the ring juncture was effected by autoxidation of the aldehyde (20) and subsequent reduction of the resulting hydroperoxide (21) to give a desired alcohol (22). Finally, the alcohol (22) was converted by two-step sequence into ptaquilosin (2) (1.1% overall yield from δ-valerolactone).
天然有機化合物討論会の論文
1987-07-25