Semicorrin metal complexes as enantioselective catalysts. Part 2. Enantioselective cyclopropane formation from olefins with diazo compounds catalyzed by chiral (semicorrinato)copper complexes
作者:Hugo Fritschi、Urs Leutenegger、Andreas Pfaltz
DOI:10.1002/hlca.19880710621
日期:1988.9.28
were obtained (Table 2). Usually, the reactions were carried out using bis(semicorrinato)copper(II) complexes as precatalysts. In order to produce active catalysts, these complexes had to be activated first by heating in the presence of diazoacetate or by treatment with phenylhydrazine. Experiments with (semicorrinato)copper(I) complexes, prepared in situ from copper(I) tert-butoxide (Scheme 4), suggest
发现手性,C 2对称半corrin配体的铜配合物是从烯烃与重氮化合物形成环丙烷的有效催化剂。在催化剂的1%模式下,重氮乙酸烷基酯与末端烯烃如苯乙烯,丁二烯和1-庚烯平稳地反应,得到相应的光学活性环丙烷羧酸衍生物(表1方案2)。使用其中一种催化剂,对映选择性高达97%ee (表2)。通常,该反应使用双(准corrinato)铜(II)配合物作为预催化剂进行。为了生产活性催化剂,必须首先通过在重氮乙酸酯存在下加热或通过苯肼处理来活化这些配合物。使用由叔丁醇铜(I)原位制备的(semicorrinato)铜(I)配合物进行的实验(方案4)表明,实际的催化剂是[单(semicorrinarinato)]铜(I)。