Substitution of Allylic Functional Acetates: Stereoselective Synthesis of 2-Alkylidene-1,5-ketoesters
摘要:
Direct reaction of allylic functional acetates 1 and beta-diketones 3 in the presence of anhydrous potassium carbonate i n boiling absolute ethanol gave 2-alkylidene-1,5-ketoesters 4 in good to fair yields.
A concise and stereoselective total synthesis of (±)-cephanolide B was achieved in 15 steps. The key steps in the synthesis were as follows: (i) an intermolecular Diels–Alder reaction followed by lactonization to form the oxabicyclo[2.2.2]octane DE ring; (ii) a tandem reaction, featuring an intramolecular Pauson–Khand reaction, a 6π-electrocyclization, and an oxidative aromatization by O2, to construct
(±)-cephanolide B 的简洁和立体选择性全合成通过 15 个步骤实现。合成的关键步骤如下:(i)分子间 Diels-Alder 反应,然后内酯化形成氧杂双环[2.2.2]辛烷 DE 环;(ii) 以分子内 Pauson-Khand 反应、6π-电环化和 O 2的氧化芳构化为特征的串联反应,以构建 ABC-三环 (6-5-6);(iii) 邻苯二甲酰过氧化物介导的芳烃氧化以安装 C-13 苯酚基团。
Evans, Elizabeth H.; Hewson, Alan T.; March, Lorraine A., Journal of the Chemical Society. Perkin transactions I, 1987, p. 137 - 150
作者:Evans, Elizabeth H.、Hewson, Alan T.、March, Lorraine A.、Nowell, Ian W.、Wadsworth, Alan H.
DOI:——
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Synthesis of α-Alkylidene-δ-valerolactones via the Conjugate Addition of Ketone Enolates to Functionalized Allyl Acetates
Sequential addition of ketone enolates to allyl acetates bearing an ester, followed by reduction and cyclization provides a variety of substituted alpha-alkylidene-delta-valerolactones.
Beltaief I., Amri H., Synth. Commun, 24 (1994) N 14, S 2003-2010