2001 Fiscal Year Final Research Report Summary
DESIGN AND SYNTHESIS OF EFFICIENT CHIRAL CATALYSTS BASED ON CONFORMATIONAL CONTROL OF SHIELDING SUBSTITUENT
| Project/Area Number |
10208213
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Research Institution | Kyushu University |
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Principal Investigator |
KANEMASA Shuji INSTITUTE OF ADVANCED MATERIAL STUDY, KYUSHU UNIVERSITY, PROFESSOR, 機能物質科学研究所, 教授 (20038590)
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| Project Period (FY) |
1998 – 2000
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| Keywords | conformational control of the shielding substituents / torelant chiral Lewis acid catalysts / strongly coordinating nucleophiles / enantioselective 1,3-dipolar cycloadditions / enantioselective conjugate additions / nitrone cycloaddition reactions / diazo cycloaddition reactions / amine conjugate addition reactions |
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| Research Abstract |
Development of a useful method of chirality control in catalyzed asymmetric reactions is one of the central subjects in the field of synthetic organic chemistry in 21st century. In the present research, we have challenged to design and synthesize efficient chiral catalysts based on conformational control of ligang skeleton as well as shielding substituents. One is a trans-chelating tridentate chiral ligand which has a dibenzofuran skeleton with two oxazoline substituents at 4- and 6-positions. The other one is a usual bisoxaloline type of chiral ligand having benzyl shielding substituents with o-hydroxyl moiety. These complexes are found to be effectively utilized in the catalyzed asymmetric reactions of strongly coordinating nucleophiles.
1. Nitrone Cycloadditions : The nickel(II) aqua complex of R,R-DBFOX/Ph ligand successfully catalyzes the nitrone cycloaddition reactions to 3-crotonoyl-2-oxazolidinone and derivatives in the catalytic loading of 2 mol% at room temperature to show ext
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remely high diastereo- and enantioselectivities.
2. Nitrone Cycloadditions Using Monodentate Dipolarophiles : The nitrone cycloaddition reactions using bromoacrolein as a monodentate dipolarophile proceed much more efficiently in the presence of the zinc(II) complexes of R,R-DBFOX/Ph ligand. It has been evidenced that this reaction proceeds through the internal delivery mechanism of the nitrone/catalyst/acceptor activated complex.
3. Diazo Cycloadditions : Excellent enantioselectivity has been attained in the diazo cycloaddition reactions between trimethylsilyldiazomethane and 3-crotonoyl-2-oxazolidinone and derivatives in the presence of the zinc(II) complexes of R,R-DBFOX/Ph ligand (10 mol%). On the other hand, similar reactions of 3-crotonoyl-4,4-dimethyl-2-oxazolidinone can be activated not by the zinc(II) and nickel(II) complexes at all but the magnesium complex. The high enantioselectivities with the opposite mode have resulted.
4. Amine Conjugate Additions : The copper(II) complex of R,R-BOX/o-HOBn ligand is found to be very useful in the amine conjugate addition reactions of O-benzylhydroxylamine to 3-isopropyl-1-crotonoyl-2-imidazolidinone. This reaction is also believed to proceed through the internal delivery mechanism. Less
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[Publications] S.Kanemasa, Y.Oderaotoshi, S.Sakaguchi, H.Yamamoto, J.Tanaka, E.Wada, D.P.Curran: "Transition Metal Aqua Complexes of 4,6-Dibenzofurandiyl-2,2'-bis(4-phenyloxazoline). Effective Catalysis in Diels-Alder Reactions Showing Excellent Enantioselectivity,Extreme Chiral Amplification,and High Tolerance to Water,Alcohols,and Acids"J.Am.Chem.Soc.. 120. 3074-3088 (1998)
Description
「研究成果報告書概要(和文)」より
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[Publications] S. Kanemasa, Y. Oderaotoshi, S. Sakaguchi, H. Yamamoto, J. Tanaka, E. Wada, D. P. Curran: "Transition Metal Aqua Complexes of 4,6-Dibenzofurandiyl-2,2'-bis(4-phenyloxazoline). Effective Catalysis in Diels-Alder Reactions Showing Excellent Enantioselectivity, Extreme Chiral Amplification, and High Tolerance to Water, Alcohols, and Acids"J. Am. Chem. Soc.. 120. 3074-3088 (1998)
Description
「研究成果報告書概要(欧文)」より
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