Nickel-catalyzed [2+2+2] cycloaddition of two alkynes and an imine
Nickel-catalyzed [2+2+2] cycloaddition of two alkynes and an imine
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DOI：
10.1351/pac200880051115
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发表时间：
2008-05-01
影响因子：
1.8
通讯作者：
Kurosawa, Hideo
中科院分区：
文献类型：
--
作者：
Ogoshi, Sensuke;Ikeda, Haruo;Kurosawa, Hideo
N-苯磺酰基苯亚甲基与Ni(cod)(2)和PCy3反应定量生成相应的eta(2)-亚胺镍络合物。二苯乙炔与eta(2)-亚胺镍配合物反应生成五元氮杂镍环。将第二个炔插入五元氮杂镍环中导致形成相应的七元氮杂镍环。加热七元氮杂镍环溶液诱导还原消除，得到1,2-二氢吡啶。在 10 mol% Ni(cod)(2) 和 (PMeBu2)-Bu-t 存在下，在 100 ℃ 下，N-苯磺酰基苯甲醛亚胺和 2-丁炔发生分子间 [2+2+2] 环加成，得到预期的 1,2-二氢吡啶，产率 87%。在 PCy3 存在下，反应也以催化方式进行，然而，(PMeBu2)-Bu-t 给出了更好的结果。体积较小或碱性较低的膦（PBu3）-Bu-n 或 P(o-tol)(3) 对于反应效率不高。尽管 Ni(0)-NHC 配合物是两个炔烃和酮或醛的 [2+2+2] 环加成的良好催化剂，但该反应在 NHC 配体 1,3-双-(2,4,6-三甲基苯基)咪唑-2-亚基存在下无法进行。
The reaction of N-benzenesulfonylbenzaldimine with Ni(cod)(2) and PCy3 gave the corresponding eta(2)-iminenickel complex quantitatively. Diphenylacetylene reacted with the eta(2)-iminenickel complex to generate five-membered aza-nickelacycle. Insertion of second alkynes into the five-membered aza-nickelacycle led to the formation of the corresponding seven-membered aza-nickelacycles. Heating the solution of the seven-membered aza-nickelacycles induced-the reductive elimination to give 1,2-dihydropyridine. In the presence of 10 mol % of Ni(cod)(2) and (PMeBu2)-Bu-t at 100 degrees C, the intermolecular [2+2+2] cycloaddition of N-benzenesulfonylbenzaldimine and 2-butyne occurred to give the expected 1,2-dihydropyridine in 87% yield. In the presence of PCy3, the reaction also proceeded catalytically, however, (PMeBu2)-Bu-t gave better results. Less bulky or less basic phosphine, (PBu3)-Bu-n or P(o-tol)(3), was not efficient for the reaction. Although Ni(0)-NHC complex was a good catalyst for [2+2+2] cycloaddition of two alkynes and a ketone or an aldehyde, this reaction did not proceed in the presence of an NHC ligand, 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene.