Stereoselective Coupling of Prochiral Radicals with a Chiral <i>C</i><sub>2</sub>-Symmetric Nitroxide
作者:Rebecca Braslau、Neeta Naik、Hendrik Zipse
DOI:10.1021/ja000520u
日期:2000.9.1
The coupling reaction between a chiral C2-symmetric nitroxide, trans-2,5-dimethyl-2,5-diphenylpyrrolidin-1-oxyl (DPPO; 1), and a series of stabilized secondary prochiral radicals was studied to determine the factors that affect stereoselectivity. Both steric and electronic perturbations on the selectivity by the substituents of the prochiral radical were observed. The effects of temperature, solvent
研究了手性 C2 对称氮氧化物、反式-2,5-二甲基-2,5-二苯基吡咯烷-1-氧基 (DPPO; 1) 和一系列稳定的二级前手性自由基之间的偶联反应,以确定影响因素立体选择性。观察到前手性基团的取代基对选择性的空间和电子扰动。检查了温度、溶剂极性和溶剂粘度的影响。在低粘度溶剂中进行的反应的高选择性为在反应路径上形成遇到复合物提供了证据。简化模型系统的从头算计算预测,在大约 2.2 A 的碳-氧键形成距离下,C-O-N 攻角大于 110°,尽管没有发现过渡态。