Regio- and stereoselectivities in Diels-Alder cyclodimerizations of orthoquinonoid cyclohexa-2,4-dienones
Regio- and stereoselectivities in Diels-Alder cyclodimerizations of orthoquinonoid cyclohexa-2,4-dienones
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DOI：
10.1016/j.tet.2007.03.035
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发表时间：
2007-07-09
期刊：
影响因子：
2.1
通讯作者：
Quideau, Stephane
中科院分区：
文献类型：
--
作者：
Gagnepain, Julien;Mereau, Raphaeel;Quideau, Stephane
[4+2]环己-2，4-二烯酮衍生物的邻苯二酮单缩醛和邻苯二酚类化合物的[4+2]环二聚反应在过去50年中一直是众多研究的主题，目的是使在这些过程中观察到的非凡的区域、位置和立体选择性水平合理化。尤其是在手性邻喹醇(即6-烷基-6-羟基环己a-2，4-二烯酮)的环二聚反应中表现出的双重非对映-面孔分化是这些转化的一个重要方面，因为它们与几种天然产物的结构有关。本文描述的实验和理论结果提供了对控制这些特定地点的区域和非对映选择性的因素的全面理解。我们对这些结果的解释依赖于Wood-ward-Hoffmann和Salem-Houk次级轨道相互作用和双周环C-2对称过渡态的Cieplak型超共轭效应的结合。(C)2007爱思唯尔有限公司。保留所有权利。
The [4+2] cyclodimerization of cyclohexa-2,4-dienone derivatives of the orthoquinone monoketal and orthoquinol types has been the topic of numerous investigations over the last 50 years in the aim of rationalizing the extraordinary level of regio-, site-, and stereoselectivities observed in these processes. In particular, the double diastereo-pi-facial differentiation expressed in cyclodimerizations of chiral orthoquinols (i.e., 6-alkyl-6-hydroxycyclohexa-2,4-dienones) is an important aspect of these transformations, for they relate to the construction of several natural products. The experimental and theoretical results that are described in this article offer a comprehensive understanding of the factors controlling these site- specific regio- and diastereoselectivities. Our interpretation of these results relies on a combination of Wood-ward-Hoffmann and Salem-Houk secondary orbital interactions and Cieplak-type hyperconjugative effects in bispericyclic C-2-symmetric transition states. (c) 2007 Elsevier Ltd. All rights reserved.