1995 Fiscal Year Final Research Report Summary
Development of optically active transition metal complexes with molecular chirality
| Project/Area Number |
06807162
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Chemical pharmacy
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| Research Institution | Tokyo University |
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Principal Investigator |
SASAI Hiroaki University of Tokyo Graduate School of Pharmaceutical Sciences, Lecturer, 大学院・薬学系研究科, 講師 (90205831)
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| Project Period (FY) |
1994 – 1995
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| Keywords | gallium / Rare Earth / Asymmetric Catalyst / Heterobimetallic / molecular chirality / Multifubctional Catalyst |
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| Research Abstract |
Asymmetric organometallic complexes are usually prepared from optically active compounds as ligands.However, some asymmetric complexes are reported to be exist without containing optically active ligands.Hitherto known stable these complexes with molecular chirality are prepared by optical resolution of racemic complexes and show no catalyst activity.In this study, we investigated asymmetric catalysts with molecular chirality.
So far, we have reported several multifunctional catalysts which contain (R) -or (S) -1,1'-bi-2-naphthol (BINOL) as a ligand.That is, the heterobimetallic lanthanoid catalysts promote asymmetric nitroaldol reactions, asymmetric Michael additions, asymmetric hydrophosphonylation of imines and/or aldehydes, etc.However when these type of lanthanoid complexes were prepared from achiral biphenol as a ligand, no asymmetric induction was observed due to the rapid ligand exchange.therefore we made examination of developing another type of complex with catalyst activity.After a number of attempts, we succeeded in obtaining asymmetric complexes which contain aluminum, and/or gallium by use of BINOL as a ligand.We also developed alkali metal free rare earth-BINOL complexes. These complexes were found to be effective in either asymmetric tandem Michael-aldol reactions, asymmetric ring opening of symmetric epoxides, or asymmetric epoxidation of enones.
Preparation of a rare earth complex from biphenol instead of BINOL in the presence of small amount of optically active diamines afforded a new complex with molecular chirality.Although the catalyst efficiency is unsatisfactory at present, we believe this type of complex would open up a new field in asymmetric synthesis.
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