Mechanistic Insights into the Reaction of Enantiomerically Pure Lithiosilanes and Electrophiles: Understanding the Differences between Aryl and Alkyl Halides
作者:Christian Däschlein、Simeon O. Bauer、Carsten Strohmann
DOI:10.1002/ejic.201000834
日期:2011.3
focus on product composition and enantiomeric ratios as a basis for a better understanding of ongoing mechanisms. Both parameters are strongly influenced by both the organic group and the corresponding halide of the used electrophile. Thus, high stereoselectivities and yields are only obtained if one distinct reaction mechanism dominates. In the case of aliphatic electrophiles, experimental and quantum
对映体纯锂硫硅烷对脂肪族和芳香族卤代亲电试剂的反应性已被研究,重点是产品组成和对映体比率,作为更好地理解正在进行的机制的基础。这两个参数都受到所用亲电试剂的有机基团和相应卤化物的强烈影响。因此,只有当一种不同的反应机制占主导地位时,才能获得高立体选择性和产率。在脂肪族亲电试剂的情况下,实验和量子化学研究支持氯化物的 SN2 机制的偏好,导致在硅上保留构型,而溴化物倾向于通过卤化物 - 锂交换(ate 络合物)在反转下反应。对于芳香族亲电试剂,这些关系发生了变化: