作者:Elizabeth H. Krenske、Sarah Lam、Jerome P. L. Ng、Brian Lo、Sze Kui Lam、Pauline Chiu、Kendall N. Houk
DOI:10.1002/anie.201503003
日期:2015.6.15
proposed for these types of reactions. Reported are theoretical and experimental investigations of the cycloaddition mechanism. The major enantiomers of the cycloadducts are derived from SN2‐like reactions of the silylated epoxide with the diene, in which stereospecific ring opening and formation of the two new CC bonds occur in a single step. Calculations predict, and experiments confirm, that the
环氧烯醇硅烷与二烯的硅烷基三氟甲磺酸酯催化的(4 + 3)环加成反应为七元碳环提供了温和且化学选择性的合成途径。包含末端烯醇硅烷和单个立体中心的环氧烯醇硅烷进行环加成,对映体纯度几乎完全守恒,这一发现与以前针对这些类型的反应提出的含氧烯丙基阳离子中间体相反。报告的是环加成机理的理论和实验研究。所述cycloadducts的主要对映体选自S衍生Ñ 2一样与二烯甲硅烷基化的环氧化物的反应中,其中两个新的C的立体有择的开环和地层C键在一个步骤中发生。计算预测和实验证实,所观察到的对映体纯度的小损失可追溯到三氟甲磺酸介导的双S N 2环加成途径。