<i>C</i><i><sub>2</sub></i>-Symmetric Copper(II) Complexes as Chiral Lewis Acids. Catalytic Enantioselective Carbonyl−Ene Reactions with Glyoxylate and Pyruvate Esters
作者:David A. Evans、Steven W. Tregay、Christopher S. Burgey、Nick A. Paras、Tomas Vojkovsky
DOI:10.1021/ja000913t
日期:2000.8.23
yield and enantioselectivity. Complex 2a has also been shown to catalyze the addition of 1,1-disubstituted olefins to methyl pyruvate in good yields (76−95%) and excellent enantioselectivies (≥98% ee). The synthetic utility of the glyoxylate−ene reaction was demonstrated by conversion of the resulting α-hydroxy ester into the corresponding methyl ester, free acid, Weinreb amide, and α-azido ester, all with
C2 对称配合物 [Cu(S,S)-叔丁基双(恶唑啉基)](SbF6)2 (2a),其双(水)对应物 [Cu(S,S)-叔丁基双(恶唑啉基)(H2O) )2](SbF6)2 (4) 和 [Cu(S,S)-苯基双(恶唑啉基)](OTf)2 (1c) 已被证明可以催化乙醛酸酯和各种烯烃之间的对映选择性烯反应。在 0.2-10 mol% 的催化剂 1、2 和 4 存在下,单取代、双取代和三取代的烯烃均与乙醛酸乙酯反应,以良好的收率和对映选择性得到烯产物。复合物 2a 也被证明可以以良好的产率 (76-95%) 和出色的对映选择性 (≥98% ee) 催化 1,1-二取代烯烃添加到丙酮酸甲酯中。通过将所得α-羟基酯转化为相应的甲酯,证明了乙醛酸-烯反应的合成效用,