Osmium-Catalyzed Olefin Dihydroxylation and Aminohydroxylation in the Second Catalytic Cycle
作者:Peng Wu、Robert Hilgraf、Valery V. Fokin
DOI:10.1002/adsc.200505252
日期:2006.6
Two catalytic cycles operate in the osmium-catalyzed olefin dihydroxylation and aminohydroxylation. Slow hydrolysis of the Os(VI) monoglycolate (or monoazaglycolate in aminohydroxylation) intermediate often results in the addition of another molecule of olefin thereby shunting the catalysis into the second catalytic cycle. As a result, both enantio- and chemoselectivity are reduced. A series of new
两个催化循环在催化的烯烃二羟基化和氨基羟基化中进行。Os(VI)单甘醇酸酯(或氨基羟基化中的单氮杂乙醇酸酯)中间体的缓慢水解通常会导致另外一个烯烃分子的加入,从而将催化作用转移到第二个催化循环中。结果,对映选择性和化学选择性均降低。设计了一系列新的螯合配体,其迫使催化进入第二个循环,同时在烯烃添加步骤中保持对映体控制。获得了优异的催化转化率和中等至良好的对映选择性。