Organozinc/Nickel(0)-Promoted Cyclizations of Bis-Enones.
Organozinc/Nickel(0)-Promoted Cyclizations of Bis-Enones.
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DOI：
10.1002/chin.199629058
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发表时间：
1996-03
期刊：
影响因子：
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通讯作者：
A. V. Savchenko;J. Montgomery
中科院分区：
文献类型：
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作者：
A. V. Savchenko;J. Montgomery
为了探索这一初步观察的一般性，我们研究了双烯酮的环化反应。在这些研究过程中观察到两种不同的环化流形，产物分布高度依赖于有机锌结构。我们的研究始于双烯酮1a和1b(式2)。2在Ni(COD)2存在下，用二苯基锌和苯基氯化锌的混合物处理1a，通过顺序共轭加成反应，以65%的产率有效地合成了三取代环己烷2a。3，4在相同的条件下处理1b，以70%的产率得到可分离的环己烷2b及其同分异构体3b的5：1混合物。这一结果与炔基烯酮的环化反应形成了鲜明的对比，在环化反应中从未观察到有机锌与烯酮的直接共轭加成。1
In order to probe the generality of this initial observation, we have examined cyclizations of bis-enones. Two distinct cyclization manifolds were observed during the course of these investigations, with product distributions being highly dependent upon organozinc structure. Our investigations began with bis-enones 1a and 1b (eq 2). 2Treatment of 1a with a mixture of diphenylzinc and phenylzinc chloride in the presence of Ni (COD) 2 resulted in the efficient production of the trisubstituted cyclohexane 2a as a single diastereomer in 65% yield by a mechanism involving sequential conjugate additions. 3, 4 Treatment of 1b under identical conditions resulted in the production of a separable 5: 1 mixture of the allequatorial cyclohexane 2b and its epimer 3b in 70% yield. This result contrasts sharply with cyclizations of alkynyl enones, in which direct conjugate addition of the organozinc to the enone was never observed. 1