A Unified Strategy for the Stereocontrolled Construction of Structurally Unusual Sesquiterpene Lactones. Asymmetric Synthesis of Vulgarolide and Deoxocrispolide
作者:Leo A. Paquette、Claudio F. Sturino、Xiaodong Wang、Jeremy C. Prodger、Dongsoo Koh
DOI:10.1021/ja960334h
日期:1996.1.1
ketone (+)-17b reacts with vinylmagnesium bromide from its exo face, thus enabling exploitation of the anionic oxy-Cope rearrangement and direct alkylation of the enolate so formed with ethyl iodoacetate to provide 24 in an efficient, stereocontrolled manner. Tricyclic lactone 26b, readily produced from 24, proved to be a common precursor to both synthetic targets. The construction of vulgarolide (9)
双环酮 (+)-17b 从其外表面与乙烯基溴化镁反应,从而能够利用阴离子氧基-Cope 重排和由此形成的烯醇化物与碘乙酸乙酯的直接烷基化,以有效、立体控制的方式提供 24。三环内酯 26b 很容易从 24 中产生,被证明是两种合成目标的常见前体。通过将 26b 中的 SEM 基团转化为甲磺酸盐以在双键氧化裂解之前转化为环氧酸 39 来构建 vulgarolide (9)。这种转化导致直接转化为 9 及其差向异构体 42。