DFT Study on the Diels-Alder Cycloaddition between Alkenyl-M(0) (M = Cr, W) Carbene Complexes and Neutral 1,3-Dienes

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• 作者：Israel Fern&aacute ; ndez ; Miguel A. Sierra ; Fernando P. Cossí ; o
• 刊名：Journal of Organic Chemistry
• 出版年：2008
• 出版时间：March 21, 2008
• 年：2008
• 卷：73
• 期：6
• 页码：2083 - 2089
• 全文大小：371K
• 年卷期：v.73,no.6(March 21, 2008)
• ISSN：1520-6904

文摘

The thermal Diels-Alder reaction between alkenylmetal(0) Fischer carbenes and 1,3-dienes (isopreneand cyclopentadiene) has been studied computationally within the density functional theory framework.The selectivity of the [4 + 2] cycloadditions between alkenyl-group 6 (Fischer) carbene complexes andisoprene is similar to the selectivity computed for the reactions involving Lewis acid complexed acrylates.The experimentally observed complete endo selectivity in the [4 + 2] cycloadditions of alkenyl-group6 (Fischer) carbene complexes with cyclopentadiene, which takes place under kinetic control, may bedue in part to the presence of stabilizing secondary orbital interactions. These interactions are strongerthan the analogues in the metal-free processes. The [4 + 2] cycloadditions between alkenyl-group 6(Fischer) carbene complexes and neutral dienes occur concertedly via transition structures which aremore asynchronous and less aromatic than their non-organometallic analogues, a behavior which isextensible to the reactions between Lewis acid complexed acrylates.