1992 Fiscal Year Final Research Report Summary
Application of empirical molecular mechanics to asymmetric oxidation of sulfides catalyzed by metal complexes
| Project/Area Number |
03453051
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
無機・錯塩・放射化学
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| Research Institution | Okayama University |
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Principal Investigator |
KOJIMA Masaaki Okayama Univ., Faculty of Sci., Associate Professor, 理学部, 助教授 (20022725)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Complex Catalyst / Asymmetric Oxidation / Molecular Mechanics / Optical Activity / Enantioselectivity / Schiff Base Complex |
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| Research Abstract |
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.
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