Kinetic Investigations Provide Additional Evidence That an Enzyme-like Binding Pocket Is Crucial for High Enantioselectivity in the Bis-Cinchona Alkaloid Catalyzed Asymmetric Dihydroxylation of Olefins
作者:E. J. Corey、Mark C. Noe
DOI:10.1021/ja952567z
日期:1996.1.1
The Sharpless enantioselective dihydroxylation of terminal olefins by OsO4 using the catalytic chiral ligand (DHQD)2PYDZ (1) has been shown to follow Michaelis−Menten kinetics, demonstrating fast reversible formation of a complex of olefin, OsO4, and 1 prior to the rate-limiting conversion to the Os(VI) ester intermediate. There is a good correlation between the observed binding constants, Km, and
使用催化手性配体 (DHQD)2PYDZ (1) 的 OsO4 对末端烯烃的 Sharpless 对映选择性二羟基化已被证明遵循 Michaelis-Menten 动力学,证明在速率-限制转化为 Os(VI) 酯中间体。观察到的结合常数 Km 与二羟基化的对映选择性程度之间存在良好的相关性,表明 1·OsO4 与底物的范德华结合对增强对映选择性速率很重要。已经使用数据的狄克逊分析动力学证明了各种化合物对氧化的抑制,并且已经确定了 Ki 值并将其与抑制剂结构相关联。最强的抑制剂是能够与 1·OsO4 复合物的 Os(VIII) 配位同时结合在由配体的芳香亚基形成的口袋中的化合物。Km 和 Ki 值之间的并行性及其关系...