We have succeeded in developing direct syntheses of trans β-azidohydrins and trans 1,2-diol derivatives from olefins catalyzed by dichlorotin oxide. The regioselectivity of these reactions with tri-substituted olefins is high (10:1 in the synthesis of 1,2-diol derivatives) to excellent (>99:1 in the synthesis of azidohydrins). It has been found that these reactions do not proceed via epoxides.
A New Synthesis of Optically Active<i>trans</i>β-Amino Alcohols by Asymmetric Ring-opening of Symmetrical Oxiranes
作者:Hiroyuki Yamashita
DOI:10.1246/cl.1987.525
日期:1987.3.5
The asymmetric ring-opening of symmetrical oxiranes with aniline or trimethylsilyl azide is effectively catalyzed by zinc (2R,3R)-tartrate or cupric (2R,3R)-tartrate to give trans N-phenyl (β-amino alcohol or trans O-trimethylsilyl 2-azido alcohols in 17–52% ee. The latter azido products can be easily converted into optically active trans β-amino alcohols by two-step procedure.
对称环氧乙烷与苯胺或三甲基甲硅烷基叠氮化物的不对称开环在 (2R,3R)-酒石酸锌或 (2R,3R)-酒石酸铜有效催化下得到反式 N-苯基(β-氨基醇或反式 O-三甲基甲硅烷基) 2-叠氮醇的 ee 含量为 17-52%。后者的叠氮产物可以通过两步程序轻松转化为光学活性的反式 β-氨基醇。
Enantiotopic Discrimination by Coordination‐Desymmetrized
<i>meso</i>
‐Ligands
coordination of different metal ions at enantiotopic positions of an achiral meso‐ligand are reported. These catalysts exhibit a pseudo‐Cs symmetry and are able to catalyze reactions demanding simultaneous involvement of two catalytic sites. The latter was demonstrated by application in the asymmetric ring‐opening of meso‐epoxides.
Cr(salen) catalysed asymmetric ring opening reactions of epoxides in room temperature ionic liquids
作者:Choong Eui Song、Chun Rim Oh、Eun Joo Roh、Dong Joon Choo
DOI:10.1039/b004645k
日期:——
Cr(salen) catalysed asymmetric ring opening reactions of epoxides with TMSN3 proceed readily in the roomtemperature ionic liquid 1-butyl-3-methylimidazolium salts ([bmim][X]) with easy catalyst/solvent recycling.
Intramolecular Acceleration of Asymmetric Epoxide Ring-Opening by Dendritic Polyglycerol Salen-Cr<sup>III</sup>Complexes
作者:Juliane Keilitz、Rainer Haag
DOI:10.1002/ejoc.200900241
日期:2009.7
We present the synthesis of symmetrical (pyrrolidine-salen)CrIII complexes immobilized on hyperbranched polyglycerol 1 through linkers of different lengths and their application in the asymmetricring-opening of meso-epoxides. This reaction proceeded through a cooperative bimetallic mechanism and for the polymeric catalysts a positive dendritic effect with regard to the reaction rate was found. In