Development of a Formal [4 + 1] Cycloaddition: Pd(OAc)<sub>2</sub>-Catalyzed Intramolecular Cyclopropanation of 1,3-Dienyl β-Keto Esters and MgI<sub>2</sub>-Promoted Vinylcyclopropane−Cyclopentene Rearrangement
作者:Rockford W. Coscia、Tristan H. Lambert
DOI:10.1021/ja809226x
日期:2009.2.25
A formal [4 + 1] cycloaddition of 1,3-dienyl beta-keto esters has been developed. This two step process involves Pd(II)-catalyzed intramolecular cyclopropanation to produce vinylcyclopropanes and a subsequent mild vinylcyclopropane-cyclopentene rearrangement promoted by MgI(2). The cyclopropanation method notably requires the use of Mg(ClO(4))(2), presumably to facilitate keto-enol tautomerization
已开发出 1,3-二烯基 β-酮酯的正式 [4 + 1] 环加成反应。这两个步骤的过程涉及 Pd(II) 催化的分子内环丙烷化以产生乙烯基环丙烷和随后由 MgI(2) 促进的温和的乙烯基环丙烷-环戊烯重排。环丙烷化方法特别需要使用 Mg(ClO(4))(2),大概是为了促进酮-烯醇互变异构化,并且通过使用异丁酸铜 (II) 作为助氧化剂大大改善。展示了一系列具有各种取代模式的底物。