Stereoselective olefination of unfunctionalized ketones via ynolates
Stereoselective olefination of unfunctionalized ketones via ynolates
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DOI：
10.1021/jo0497813
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发表时间：
2004-05-28
影响因子：
3.6
通讯作者：
Shishido, K
中科院分区：
文献类型：
--
作者：
Shindo, M;Sato, Y;Shishido, K
烯醇化物与酮在室温下反应，得到α，β，β-三取代丙烯酸酯（四取代烯烃），其几何选择性为2：1-8：1。这可以被认为是一种新的酮的烯烃化反应，即使在空间位阻底物的情况下，也能以良好的产率得到四取代烯烃。反应机理涉及烯醇化物与羰基的环加成反应和随后的所得β-内酯烯醇化物的热电环开环反应。立体选择性是在开环中确定的，开环由反式选择性调节。本文介绍了酮的烯醇化反应的研究范围和局限性，并讨论了其立体控制机理。
Ynolates react with ketones at room temperature to afford a,beta,beta-trisubstituted acrylates (tetra-substituted olefins) with 2:1-8:1 geometrical selectivities. This can be regarded as a new olefination reaction of ketones giving tetrasubstituted olefins in good yield, even in the case of sterically hindered substrates. The reaction mechanism involves cycloaddition of ynolates with a carbonyl group and subsequent thermal electrocyclic ring-opening of the resulting beta-lactone enolates. The stereoselectivity is determined in the ring-opening, which is regulated by torquoselectivity. In this paper, we describe the scope and limitations of olefination of ketones via ynolates and discuss the stereocontrol mechanism.