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Application of empirical molecular mechanics to asymmetric oxidation of sulfides catalyzed by metal complexes

经验分子力学在金属配合物催化硫化物不对称氧化中的应用

基本信息

批准号：
03453051
负责人：
KOJIMA Masaaki
金额：
$ 4.16万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

1. X-ray Structure Analyses of Complex Catalysts.Since molecular mechanics is an empirical method, the setting of suitable parameters is essential in order to obtain reliable results. For this purpose, we have carried out X-ray structure analyses of optically active Schiff base- manganese(III), -cobalt(II), and -oxovanadium(V) complexes.2. Conformational Analyses by Means of Molecular Mechanics.Molecular mechanics calculations (MMP2) were carried out on the above complexes. The computed geometries agree fairly well with those observed in the crystal structures. However, the refinement of several parameters seems to be necessary for more detailed discussion.3. Asymmetric Oxidation of Sulfides.Asymmetric oxidation of prochiral organic sulfides into optically active sulfoxides was carried out with organic hydroperoxides catalyzed by metal complexes containing an optically active Schiff base ligand;the highest enantiomeric excess (ee) was ca. 60%. The orientation of phenyl groups was suggested to play an important role in asymmetric catalytic reactions. Thus, we prepared a manganese(III) complex of a Schiff base ligand involving four phenyl groups, and the catalytic properties were studied. Unexpectedly, the catalytic oxidation induced low enantioselectivity. It was realized that fine tuning of the geometry around the active site is very important to get high ee's.

1.复合催化剂的X射线结构分析由于分子力学是一种经验方法，为了获得可靠的结果，设置合适的参数是必不可少的。为此，我们对具有光学活性的席夫碱-锰（III）、-钴（II）和-钒氧（V）配合物进行了X射线结构分析.用分子力学方法进行构象分析。对上述配合物进行了分子力学计算（MMP 2）。计算的几何形状与晶体结构中观察到的几何形状相当吻合。然而，似乎有必要对几个参数进行细化，以便进行更详细的讨论。硫化物的不对称氧化.将前手性有机硫化物不对称氧化成光学活性亚砜是用有机氢过氧化物进行的，所述有机氢过氧化物由含有光学活性席夫碱配体的金属络合物催化;最高对映体过量（ee）为约100。百分之六十苯基的取向在不对称催化反应中起着重要的作用。因此，我们制备了一个锰（III）配合物的席夫碱配体涉及四个苯基，和催化性能进行了研究。出乎意料的是，催化氧化诱导低的对映选择性。人们认识到，微调的几何形状周围的活性位点是非常重要的，以获得高ee的。