52 2,3-ジアルキルシクロペンタノンエノレートのジアステレオメリックなメチル化と,それを応用した光学活性エストロンの合成

概要

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Diastereoselective methylation of the enolates derived by the Michael addition of alkyl groups to 2-alkylcyclopentenones 13, 14 gave the unexpected products 15, 17 and 19 formed by the cis attack of electrophiles from a hindered side as the major isomers. The preferential formation of the cis-isomers 15, 17 and 19 can be understood by the product development control. We also describe the synthesis of optically active estrone (38) and its C(7)-alkyl derivative 44, in which the correct absolute configuration was produced by highly enantioselective Michael addition of the cis-vinylcopper phosphine complex 30 to 2-alkylcyclopentenone 24, prepared by palladium-catalyzed decarboxylation-dehydrogenation of β-keto ester 27, and subsequent methylation.
天然有機化合物討論会の論文
1986-09-09