5H-Cyclopentapyrazines from 1,2-Dialkynylimidazoles
5H-Cyclopentapyrazines from 1,2-Dialkynylimidazoles
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1,2-二炔基咪唑制备 5H-环戊吡嗪
DOI：
10.1055/s-2004-825628
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发表时间：
2004
期刊：
影响因子：
2
通讯作者：
Asha K. Nadipuram
中科院分区：
文献类型：
--
作者：
S. Kerwin;Asha K. Nadipuram
非环C，N-二芳基亚胺类化合物是近年来发现的一类偶氮烯二炔类化合物，经Bergman型环化反应生成未反应的2，5-二氢吡啶中间体，然后缩合成β-丙烯腈异构体产物。为了确定杂环中引入氮杂二炔官能团对体系热重排的影响，我们合成了一系列1，2-二烷基咪唑类化合物，并研究了它们在1，4-环己二烯中的热重排反应。主要产物为spiro[bicyclo[4.1.0]heptane-7，5‘-[5H]cyclopentapyrazines]和5H-环五吡嗪，推测是从相应的环五氮杂卡宾中间体衍生而来的。在这一过程中涉及的显着的分子重排是根据提出的氮杂-伯格曼-复古-氮杂-伯格曼级联进行的。
Acyclic C,N-dialkynylimines are a class of aza-enediynes that have been recently shown to undergo Bergman-type cyclization to unreactive 2,5-didehydropyridine intermediates, which collapse to isomeric β-acrylonitrile products. In an effort to determine the effect of incorporating the aza-enediyne functionality into heterocyclic rings on the thermal rearrangements of these systems, we have prepared a series of 1,2-dialkynylimidazoles, whose thermal rearrangement in 1,4-cyclohexadiene were studied. The major products are spiro[bicyclo[4.1.0]heptane-7,5'-[5H]cyclopentapyrazines] and 5H-cyclopentapyrazines, presumably derived from the corresponding cyclopentapyrazine carbene intermediates. The remarkable molecular rearrangements involved in this process are examined in light of a proposed aza-Bergman-retro-aza-Bergman cascade.