stability up to 80 °C. The reactivity of the new catalysts in ring-closing metathesis is directly related to the increased steric bulk of the NHC ligand. The new catalysts have been evaluated in desymmetrization reactions and the nature of the N-alkyl group of the NHC ligands has been shown to have an important effect on the observed enantioselectivities.
制备了四种新的具有基于苄基(Bn)或正丙基(n -Pr)N-烷基的N-杂环卡宾(NHC)
配体的
钌基烯烃复分解催化剂。为合成所需的二氢
咪唑鎓盐而开发的合成路线是通用的。带有较大N-烷基的较大NHC
配体的催化剂在高达80°C的温度下具有改善的热稳定性和溶液状态稳定性。新催化剂在闭环复分解反应中的反应性直接与NHC
配体的空间体积增加有关。已经在脱对称反应中评估了新催化剂,并且已经证明了NHC
配体的N-烷基的性质对所观察到的对映选择性具有重要影响。