45 Prostaglandin合成中間体の立体選択的合成

概要

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1) Tricyclic tetrahydrofuran derivative(4) which was prepared from norbornadiene(3) was shown to be an excellent synthon for the preparation of the Corey aldehyde(16). (4) was cleaved reductively to the bicyclic ketene dichloride(5) with zinc and acetic acid which on tosylation, followed by the solvolysis afforded the epimeric tricyclic acetate(7). Hydrolysis, followed by the Jones oxidation of (7) yielded the tricyclic ketone(11) in excellent yield. Cyclopropane ring of (11) was cleaved with hydrobromic acid to give the bromo-ketone(12) which upon the Baeyer-Villiger oxidation, followed by heating with ethanol afforded the monocyclic ester(14). (14) was treated with silver perchlorate to give the lactone(15: R=H) which was converted to the Corey aldehyde(16) in excellent yield via the 4-phenylbenzoate(15: R=4-Ph-PhC-). 2) Optical active prostaglandin synthon(18) was prepared from the non-chiral diacetate(19) using micro-organisms. (19) was agitated aerobically with Bacillus subtilis var. Niger to give the chiral mono-acetate(20) which on heating with ethyl orthoacetate to give the ester(22). Hydrolysis, followed by acid cyclization of (22) afforded the optically active lactone (18).
天然有機化合物討論会の論文
1976-09-20