| Co-Investigator(Kenkyū-buntansha) |
TAKANORI Shibata Okayama University, Faculty of Science, Associate Proffessor, 理学部, 助教授 (80265735)
ITARU Sato Tokyo University of Science, Faculty of Science, Assistant, 理学部, 助手 (80318196)
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| Research Abstract |
Asymmetric autocatalysis has been developed. Chiral 2-alkynyl-5-pyrimidyl alkanol was found to be a highly enantioselective asymmetric autocatalyst in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde. PracticaUy perfect asymmetric autocatalysis(>99%. >99.5% ee) is achieved. The product has been used as asymmetric autocatalyst for the next asymmetric autocatalysis. During the ten consecutive asymmetric autocatalyses, the initial pyrimidyl alkanol has automultiplied by a factor of 60 million. It was also found that the enantiomeric excess is enhanced in the asymmetric autocatalysis. When the asymmetric autocatalyst with only 0.1% ee was employed, the ee was enhanced up to >99.5% ee. In the presence of L-leucine with only 2% ee, the reaction between pyrimidine-5-carbaldehyde and diisopropylzinc afforded pyrimidyl alkanol with higher ee. This is the first example of the correlation of the chirality of circularly polarized light (CPL) with a chiral organic compo
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und with high ee. Chiral hydrocarbon, i. e., hexahelicene, serves as a chiral initiator, and pyrimidyl alkanol with high ee was obtained. Chral inorganic crystals such as quartz and sodium chlorate work as chiral initiators. In the presence of d-quartz, (S)-pyrimidyl alkanol with 98% ee was obtained. On the other hand, in the presence of I-quartz, (R)-alkanol with 98% ee was formed. As described, we found asymmetric autocatalysis in which the ee of organic compound increases without the need for any other chiral auxiliary. Amplification from 0.1% ee to>99.5% ee has been achieved. Chiral organic compounds with low ee work as chiral initiators to afford pyrimidyl alkanol with higher ee. By using asymmetric autocatalysis, chirality of CPL is correlated with organic compound of high ee. Chiral inorganic crystals act as chiral initiators in asymmetric autocatalysis, and pyrimidyl alkanol with very high ee was formed. This is the first example of a highly enantioselective synthesis induced by chiral inorganic crystal. Less
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