Ionic hydrogenation of oxyallyl intermediates: the reductive Nazarov cyclization
Ionic hydrogenation of oxyallyl intermediates: the reductive Nazarov cyclization
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DOI：
10.1016/s0040-4020(00)00866-8
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发表时间：
2000-12-22
期刊：
影响因子：
2.1
通讯作者：
West, FG
中科院分区：
文献类型：
--
作者：
Giese, S;West, FG
在三乙基硅烷存在下，三取代和四取代二烯酮1在Lewis酸性条件下环化生成硅烯醇醚6或环戊酮7，产率从好到好取决于加工条件。所提出的反应机理包括初始的纳扎罗夫环化得到氧烯丙基中间体5，这些中间体通过氢化物的分子间转移而被截留。反应进行得干净利落，只需2当量。在大多数情况下，可以使用催化量的路易斯酸。在不对称的情况下，Et3SiD的捕获发生在较少的替代末端。(C)2000爱思唯尔科学有限公司。保留所有权利。
Cyclization of tri- and tetrasubstituted dienones 1 under Lewis acidic conditions in the presence of triethylsilane led to formation of either silyl enol ethers 6 or cyclopentanones 7 in good to excellent yields, depending on work-up conditions. The proposed mechanism involves initial Nazarov cyclization to give oxyallyl intermediates 5, which are intercepted via intermolecular transfer of hydride. The reactions proceeded cleanly with as little as 2 equiv. of silane and in most cases catalytic amounts of Lewis acid could be used. Trapping with Et3SiD occurs at the less substituted terminus in unsymmetrical cases. (C) 2000 Elsevier Science Ltd. All rights reserved.