作者:Fang Fang、Fang Xie、Han Yu、Hui Zhang、Bo Yang、Wanbin Zhang
DOI:10.1016/j.tetlet.2009.09.078
日期:2009.12
enantioselectivity for the carbonyl-ene reaction of methylstyrene and ethyl glyoxylate. 3,3′,5,5′-Tetrasubstituted groups showed a remarkable effect on both enantioselectivity and yield. With 9d prepared from 3,3′,5,5′-tetramethyl-2,2′,6,6′-tetrahydroxy biphenyl 4d as the catalyst, the best result, up to 97.6% ee and 99% yield, was obtained. Additionally, the bimetallic catalyst 9 also showed better catalytic
开发了新的非手性3,3',5,5'-四取代-2,2',6,6'-四羟基联苯配体4。配位体的轴向手性可以通过2,2',6,6'-四羟基与(R)-BINOL-Ti(O i Pr)2的螯合来诱导,以形成轴向手性双金属钛催化剂9。与(R)-BINOL-Ti(O i Pr)2催化剂相比,该新型催化剂9对于甲基苯乙烯和乙醛酸乙酯的羰基-烯反应显示出优异的活性和对映选择性。3,3',5,5'-四取代基对对映选择性和收率均显示出显着影响。与9d以3,3′,5,5′-四甲基-2,2′,6,6′-四羟基联苯4d为催化剂制备得到的最佳结果,ee高达97.6%,产率为99%。另外,双金属催化剂9也显示出比相应的单金属催化剂更好的催化能力。