Suppressed β-Effect of Silicon in 3-Silylated Monocyclic β-Lactams: The Role of Antiaromaticity
作者:Subhendu Sekhar Bag、Rajen Kundu、Amit Basak、Zdenek Slanina
DOI:10.1021/ol902411r
日期:2009.12.17
β-stabilizing effect of silicon substituent at C-3 on a C-4 cation and a radical in the 2-azetidinone systems is studied using NMR kinetics. While the β-effect is virtually nonexistent in the case of a cation, a foiled β-effect (only a 3-fold rate enhancement) is observed for a radical intermediate. From both the experimental and theoretical studies, it is demonstrated that antiaromaticity is playing
使用NMR动力学研究了C-3处的硅取代基对C-4阳离子和2-氮杂环丁酮系统中的自由基的β稳定作用。虽然在阳离子的情况下实际上不存在β效应,但对于自由基中间体,却观察到了箔状的β效应(仅3倍速率增强)。通过实验和理论研究,证明抗芳香性在抑制硅的β-稳定作用中起主要作用。