14 Clerodin類縁体の合成研究 : 構造と生物活性相関の合成的研究

概要

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Diterpenes which have a neo-clerodane skeleton such as clerodin, clerodendrin A, and caryoptin showed the absolute antifeeding activity for the larvae of insects, and it had been showed that the perhydrofuro[2,3-b]furan ring in their structure was the active center of the activity. In order to elucidate the structure-activity relationship of the absolute antifeeding substances, a clerodin homologue 4 was synthesized via 18 steps using gentisic acid as a starting material. We selected the epoxide derivative 8 as a key intermediate for the synthesis of 4, since the derivation of the oxirane ring to the perhydrofuro[2,3-b]furan ring had been already established by the method which led to the formation of a furan-alcohol derivative by Li di(3-furyl)cuprate. The hemiacetal acetate of 4 was hydrolyzed on silica gel (Kieselgel 60 pF_<254>), and, moreover, 4 gave a ring-opening product, tri-MeOH adduct 28, by the reaction with methanol in a catalytic amount of p-toluenesulfonic acid. These behaviors in 4 agreed with those of the perhydrofuro[2,3-b]furan rings in 1 and 2. It was suggested that C-8 and/or C-9 methyl groups in neo-clerodane diterpenes would considerably contribute to the stability of the perhydrofuro[2,3-b]furan ring.
天然有機化合物討論会の論文
1979-09-20