2003 Fiscal Year Final Research Report Summary
Generation of Chiral Acvliminium Ions
| Project/Area Number |
13450375
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Synthetic chemistry
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| Research Institution | Nagasaki University |
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Principal Investigator |
MATSUMURA Yoshihiro Nagasaki University, Graduate School of Biomedical Department of Pharmaceutical Sciences, Professor, 大学院・医歯薬学総合研究所, 教授 (60026309)
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| Co-Investigator(Kenkyū-buntansha) |
MAKI Toshihide Nagasaki University, Graduate School of Biomedical Department of Pharmaceutical Sciences, Associate Professor, 大学院・医歯薬学総合研究所, 助手 (10291535)
ONOMURA Osamu Nagasaki University, Graduate School of Biomedical Department of Pharmaceutical Sciences, Associate Professor, 大学院・医歯薬学総合研究所, 助教授 (60304961)
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| Project Period (FY) |
2001 – 2003
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| Keywords | iminium ion / electrochemical oxidation / α-amino acid / memory of chirality / pyrrolidine / piperidine |
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| Research Abstract |
Exploitation, of efficient methods for the synthesis of optically active nitrogen-heterocycles, particularly a-substituted piperidines and pyrrolidines, is important because those compounds are often used as synthetic precursors of chiral drugs. In our continuing study on an electrochemical generation of acyliminium ions from N-acylated cyclic a-amino acids followed by the trapping of the iminium ion intermediates with nucleophiles to afford a-substituted peperidmes and pyrrolidines, we have already found conditions for memory of chirality in which the chirality of starting a-amino acids is preserved in the products even though iminium ions might be involved as the intermediates in the transformation. However, the efficiency of memory of chirality has not yet been high. So, we scrutinized a variety of factors to affect on the memory of chirality in the generation of chiral acyliminium ions. The results obtained this year are summarized as follows.
(1)Structural effect on the memory of chirality : High memory of chirality (83〜91%ee) can be observed in a case that both N-protecting.group and the structure of α-amino acids are bulky, Moderate %ee (for example, 46%ee) of memory of chirality is available in a case of non-bulky α-amino acids having bulky N-protecting group, Any memory of chirality can not be observed in a case of non-bulky N-protecting group of α-amino acids. (2)Chiral Lewis acid-catalyzed C-C bond forming reaction between N-benzoylated iminium ions and active methylene compounds : The reaction of Cu(II) with optically active bis-oxazoline gave dynamic chiral Cu ions catalyst which had an ability to promote,an asymmetric C-C bond forming reaction between N-acylpiperidinium ions and dimethyl malonate with a moderate enantioselectivity.
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