35 Cubebane型およびZizaane型セスキテルペノイドの合成

概要

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A) Cubebane-type sesquiterpenoids, α-cubebene (Ia), β-cubebene (Ib) and cubebol (II) were synthesized according to Scheme 1. The unsaturated acid (IX) was prepared from (-)-caran-2-one (V). The diazoketone (X) derived from IX was heated with copper powder giving a mixture of the ketones (XIa-c), Upon hydrogenation XIa gave the saturated ketone (XIIa) identical with the norketone from β-cubebene. Reaction of XIIa with Wittig reagent or with Grignard reagent yielded β-cubebene or cubebol, respectively, and the latter product was dehydrated to α-cubebene. B) The synthesis of methyl epizizanoate (XXVI), whose transformation to other zizaane-type sesquiterpenoids has been reported, is presented. The diolester (XXIV) was synthesized from (+)-camphenecarboxylic acid (XV) as shown in Scheme 2. The monomesylate of XXIV rearranged to the ketoester (XXV) with t-butoxide under mild reaction condition. An equilibrium between XXV and XXVI was attained by prolonged treatment with base. Both ketoesters (XXV and XXVI) were identical with the degradation products of methyl epozizanoate, and XXVI afforded methyl epizizanoate by Wittig reaction.
天然有機化合物討論会の論文
1969-09-01