Application of S,N-Chelating Chiral Zinc Bis(aminoarenethiolates) as New Precursor Catalysts in the Enantioselective Addition of Dialkylzincs to Aldehydes
作者:Evelien Rijnberg、Neldes J. Hovestad、Arjan W. Kleij、Johann T. B. H. Jastrzebski、Jaap Boersma、Maurits D. Janssen、Anthony L. Spek、Gerard van Koten
DOI:10.1021/om9701478
日期:1997.6.1
Cyclic N(CH2)4 or N(CH2)5 amino-substituted aminoarenethiolate ligands considerably enhanced the reaction rates, resulting in shorter reaction times and higher ee's. The mechanism of these 1,2-addition reactions has the general characteristics as reported by Noyori et al. This conclusion is based on the synthesis, isolation, and characterization (X-ray, 1H and 13C NMR) of the enantiopure zinc bis(aminoarenethiolate)
一种新的对映体纯S,N-螯合锌双(aminoarenethiolate),(R,R)-Zn(SC 6 H ^ 4 C(Me)的HNME 2 -2)2((R,R) -图3b),已经合成通过(的反应- [R )三甲基甲硅烷aminoarenethiolate物种([R )-图2b用的ZnCl 2在2:1的摩尔比。(R,R)-3b是将二烷基锌化合物添加到脂肪族和芳香族醛类中的有效催化剂,在温和的反应条件下,其光学纯度为69-99%ee,以接近定量的产率得到相应的仲醇。尽管使用仅包含一个立体异构(碳)中心的简单配体获得了极好的选择性,但仍对氨基取代基的进一步修饰进行了研究。环状的N(CH 2)4或N(CH 2)5氨基取代的氨基芳硫醇盐配体大大提高了反应速率,缩短了反应时间,提高了ee值。这些1,2-加成反应的机理具有Noyori等报道的一般特征。该结论基于对映纯双(氨基芳硫醇盐)和有机锌氨基芳