过渡金属催化的双环[2.2.1]庚-2,5-二烯（降冰片二烯）与双环[2.2.2]辛-2,5-二烯的[4 + 2 + 2]环加成反应
Transition metal-catalyzed [4 + 2 + 2] cycloadditions of bicyclo[2.2.1]hepta-2,5-dienes (norbornadienes) and bicyclo[2.2.2]octa-2,5-dienes.
作者信息
Chen Y, Kiattansakul R, Ma B, Snyder J K
机构信息
Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
出版信息
J Org Chem. 2001 Oct 19;66(21):6932-42. doi: 10.1021/jo010268o.
The transition-metal-catalyzed [4 + 2 + 2] cycloadditions of norbornadienes, bicyclo[2.2.2]octa-2,5-diene, and benzobarrelene with 1,3-butadienes proceed in excellent yields using cobalt-based catalytic systems. Two key distinctions between these [4 + 2 + 2] cycloadditions and the corresponding transition-metal-catalyzed [2 + 2 +2] reactions of norbornadiene are the requirement of a bimetal catalytic system with a bisphosphine ligand for the former and exclusive regioselectivity in the [4 + 2 + 2] reaction of 2-substituted norbornadienes to produce 1-substituted adducts. These distinctions may indicate two distinct mechanisms for the [4 + 2 + 2] and [2 + 2 + 2] reactions.
使用钴基催化体系，降冰片二烯、双环[2.2.2]辛-2,5-二烯和苯并桶烯与1,3-丁二烯进行的过渡金属催化的[4 + 2 + 2]环加成反应能以优异的产率进行。这些[4 + 2 + 2]环加成反应与相应的降冰片二烯过渡金属催化的[2 + 2 + 2]反应之间的两个关键区别在于，前者需要带有双膦配体的双金属催化体系，以及2-取代降冰片二烯在[4 + 2 + 2]反应中生成1-取代加合物时具有独特的区域选择性。这些区别可能表明[4 + 2 + 2]和[2 + 2 + 2]反应存在两种不同的机理。
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