STUDY OF PHOTOCHEMICAL REACTIONS OF 2-CYCLOHEXENONES WITH SUBSTITUTED OLEFINS
STUDY OF PHOTOCHEMICAL REACTIONS OF 2-CYCLOHEXENONES WITH SUBSTITUTED OLEFINS
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DOI：
10.1021/ja01078a034
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发表时间：
1964-01-01
影响因子：
15
通讯作者：
BASS, JD
中科院分区：
文献类型：
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作者：
COREY, EJ;LEMAHIEU, R;BASS, JD
研究了 2-环己烯酮和其他共轭烯酮与各种不饱和物质的光化学反应，以确定环加成的范围、方向和立体化学。证实了显着方向特异性的出现以及伊拉罗斯稠合环系统的频繁形成。通过竞争实验测量了许多烯烃底物对激发的 2-环己烯酮攻击的敏感性，该实验建立了以下系列：1, 1-二甲氧基乙烯>甲氧基乙烯>环戊烯>异丁烯>异丙烯腈。提出了一个假设来解释（1）观察到的取向特异性，（2）光加成的立体化学，以及（3）不同烯烃与激发的 2-环己烯酮的相对反应性。因为已经发现定向专一性和高烯烃反应性与那些良好供体的烯烃一致并出现，所以这些因素在理论上是相关的；对于好捐助者来说，定向复合体被视为中间体。通过环加成生成环丁烷单元似乎发生在两个不同的阶段，并依次形成两个新的碳-碳键，即，至少在某些情况下，通过 1, 4-双自由基系统。在这些实验室最近关于石竹烯全合成的研究计划中，2 对双环酮 I 的可能合成路线进行了调查，并发现异丁烯和2-环己烯酮是一种高效实用的一步法。该反应是通过超
The photochemical reactions of 2-cyclohexenone and other conjugated enones with a variety of unsaturated substances have been investigated to determine the scope, orientation, and stereochemistry of cycloaddition. The occurrence of marked orientational specificity is confirmed as is the frequent formation of íraros-fused ring systems. Thesusceptibility of a number of olefinic substrates to attack by excited 2-cyclohexenone has been measured by competition experiments which establish theseries: 1, 1-dimethoxyethylene> methoxyethylene> cyclopentene> isobutylene> aliene» acrylonitrile. An hypothesis is advanced to explain (1) the observed orientational specificity,(2) the stereochemistry of photoaddition, and (3) the relative reactivity of different olefins with excited 2-cyclohexenone. Because orientational specificity and high olefin reactivity have been found to coincide and to appear with those olefins which are good-donors, these factors are linked in the theory; for good-donors an oriented-complex is considered as an intermediate. The generation of a cyclo-butane unit by cycloaddition seems to occur in two distinct stages with sequential formation of thetwo new car-bon-carbon bonds, ie, via a 1, 4-diradical system, at least incertain instances.During the recent program of research in these laboratories on the total synthesis of caryophyllene, 2 an investigation was made of possible synthetic routes to the bicyclic ketone I and it was discovered that the photochemical cycloaddition of isobutylene and 2-cyclohexenone was an efficient and practical one-step procedure. This reaction which was effected by ultra-