1999 Fiscal Year Final Research Report Summary
Solid-State Asymmetric Reaction by Use of Chiral Crystal Environment
| Project/Area Number |
09640651
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Organic chemistry
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| Research Institution | Niigata College of Pharmacy |
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Principal Investigator |
OHGO Yoshiaki Niigata College of Pharmacy, Pharmacy, Professor, 薬学部, 教授 (10016115)
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| Co-Investigator(Kenkyū-buntansha) |
ARAI Yoshifusa Niigata College of Pharmacy, Pharmacy, Research Associate, 薬学部, 助手 (40202725)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Solid-State Reaction / Asymmetric Reaction / Isomerization / Photoreaction / Chiral Lattice / Organocobalt Complex / Optically Active |
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| Research Abstract |
Solid state-specific and unidirectional photoisomerization and chiral lattice-controlled asymmetric (γ→β→α) photoisomerization of 3-cyanopropyl cobaloxime complexes were found to occur on visible light-irradiation of 3-cyanopropylcobaloxime complexes. Maximum enantioselectivities reached up to 91%ee. In general, the reaction rate of the second step (β→α) was much faster than that of the first step (γ→β) and the enantioselectivity of the second step was much higher than that of the first step.
In extensive investigations of this type of reactions, we also found several unusual examples in which the reaction rate of the first step was faster than that of the second step or the enantioselectivity of the first step was higher than that of the second step.
The configuration of the major enantiomer of alpha-complexes produced was found to be predictable from the shape of the reaction cavity drawn based on the crystal structure, in all cases examined, and the unusual results were also elucidated from the shape of the reaction cavity. Finally, we investigated X-ray crystal structure analyses of intermediate reaction stages of an interesting example in which the configuration of the major enantiomer had presumably been reversed on isomerization from the β-complex to the α-complex. Thus, we could directly observe the major enantiomer of the intermediate beta-substituted propyl complex, whose configuration and conformation agreed with those predicted from the shape of the reaction cavity of the 3-substituted propyl complex. By introducing large substituents such as phenyl or furyl group on the planar glyoxime ligand, the reaction rate was extremely enhanced in a series of 2-cyanoethyl complexes, and also enantioselectivity was extremely improved in a series of 2-methoxycarbonylethyl complexes.
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Research Products
(12 results)
