An extremely facile aza-Bergman rearrangement of sterically unencumbered acyclic 3-aza-3-ene-1,5-diynes.
An extremely facile aza-Bergman rearrangement of sterically unencumbered acyclic 3-aza-3-ene-1,5-diynes.
复制标题
空间无阻碍的无环 3-氮杂-3-烯-1,5-二炔的极其容易的氮杂-伯格曼重排。
DOI：
10.1021/jo0267192
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
S. Kerwin
中科院分区：
文献类型：
--
作者：
Li;Dalip Kumar;S. Kerwin
影响氮杂合烯二炔（C， n -二炔基亚胺）氮杂合-褒曼环化动力学的因素先前尚未阐明。本文报道了一系列6-三异丙基硅基和6-未取代的1-苯基-4-芳基-3-氮杂-3-烯-1,4-二炔的aza-Bergman反应的动力学研究，其中芳基为苯基、邻（甲氧基）苯基或对（甲氧基）苯基。这些氮杂烯二炔是由相应的1-芳基-3-（三异丙基硅基）丙基肟以中等产率制备的单异构体。这些叠氮烯二炔经过叠氮-褒曼反应，然后进行快速的反叠氮-褒曼环化，得到-炔基丙烯腈产品。在任何情况下，与捕获中间体2,5-二脱氢吡啶二自由基相对应的产物都不会被分离。4-芳基取代基的性质对aza-Bergman环化的速率影响不大，而6-芳基取代基的性质对aza-Bergman环化的速率影响很大。缺乏6取代基的1-苯基-4-芳基-3-叠氮-3-烯-1,5-二炔在20℃下自发进行叠氮- bergman环化，一级半衰期为36-78 min。研究了溶剂对1,4-二苯基-3-叠氮-3-烯-1,5-二炔的aza-Bergman环化动力学的影响。这种环化的速率与溶剂有关，在极性较低的溶剂中进行得更快。
The factors that affect the kinetics of the aza-Bergman cyclization of aza-enediynes (C,N-dialkynyl imines) have not previously been elucidated. Here we report our kinetic studies of the aza-Bergman reactions of a series of 6-triisopropylsilyl and 6-unsubstituted 1-phenyl-4-aryl-3-aza-3-ene-1,4-diynes in which the aryl group is phenyl, o-(methoxy)phenyl, or p-(methoxy)phenyl. These aza-enediynes are prepared as single isomers in modest yield from the corresponding 1-aryl-3-(triisopropylsilyl)propynone oximes. These aza-enediynes undergo aza-Bergman reaction followed by a rapid retro-aza-Bergman cyclization to afford beta-alkynyl acrylonitrile products. In no case are products corresponding to trapping the intermediate 2,5-didehydropyridine diradical isolated. While the rate of aza-Bergman cyclization is not greatly affected by the nature of the 4-aryl substituent, the rate is very dependent on the nature of the 6-substituent. 1-Phenyl-4-aryl-3-aza-3-ene-1,5-diynes that lack a 6-substituent undergo aza-Bergman cyclization spontaneously at 20 degrees C with first-order half-lives of 36-78 min. The effect of solvent on the kinetics of aza-Bergman cyclization of 1,4-diphenyl-3-aza-3-ene-1,5-diyne was investigated. The rate of this cyclization is solvent dependent, proceeding more rapidly in less polar solvents.
影响因子：
15
作者：
Jones, GB;Warner, PM
通讯作者：
Warner, PM