Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations
作者:Shi Chen、Ahmad A. Ibrahim、Nicholas J. Peraino、Divya Nalla、Mukulesh Mondal、Maxwell Van Raaphorst、Nessan J. Kerrigan
DOI:10.1021/acs.joc.6b01481
日期:2016.9.2
scope exploration, protocol innovations (including double in situ ketene generation for 7 examples), and an application to a cinnabaramide A intermediate are described. The addition of lithium perchlorate (1–2 equiv) as an additive to the alkaloid catalyst system was found to favor formation of the E isomer of the ketene heterodimer. Ten examples were formed with moderate to excellent (E)-olefin isomer
在本文中,我们描述了烯酮催化不对称异二聚生成烯酮异二聚体β-内酯的广泛研究。确定最佳催化体系为金鸡纳生物碱衍生物(TMS-奎宁或Me-奎尼丁)。获得所需的烯酮异二聚体β-内酯,收率良好至优异(高达90%),对映选择性水平优异(对于33 Z和E异构体实例,ee≥90%ee ),良好至优异(Z)-烯烃异构体选择性(对于20个实例,≥90:10)和出色的区域选择性(仅形成一种区域异构体)。描述了催化剂开发研究,催化剂负载研究,底物范围探索,方案创新(包括7个实例的双原位乙烯酮生成)以及对肉桂脂A中间体的应用的详细信息。发现向生物碱催化剂体系中添加高氯酸锂(1-2当量)作为添加剂有利于乙烯酮异二聚体的E异构体的形成。形成了十个具有中等至优异的(E)-烯烃异构体选择性(74:25至97:3)和出色的对映选择性(84-98%ee)的样品。