Friday Seminar: Kenso Soai – Københavns Universitet

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Friday Seminar:

Asymmetric Autocatalysis and the Origin of Homochirality

Kenso Soai

Department of Applied Chemistry, Tokyo University of Science,

Kagurazaka, Shinjuku-ku, Tokyo, Japan

soai@rs.kagu.tus.ac.jp

 

Asymmetric autocatalysis is a reaction in which chiral product acts as a chiral catalyst for its own formation. The process is a catalytic self-replication of chiral molecule, and has advantages over usual asymmetric catalysis: (1) because the product becomes catalyst, the amount of catalyst increases and no decrease in the catalytic activity, (2) because the structure of the asymmetric autocatalyst and the product is the same, no need to separate the product from catalyst.

We found asymmetric autocatalysis of enantiomeric excess of pyrimidyl alkanol in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde.1 Significant amplification of ee is observed in the asymmetric autocatalysis. Starting from pyrimidyl alkanol with only ca. 0.00005% ee as asymmetric autocatalyst, pyrimidyl alkanol with >99.5% ee was formed in consecutive asymmetric autocatalysis.2 Point-to-point ultra-remote asymmetric control (1,39-asymmetric induction) with flexible linker is observed by using the principle of direct supramolecular orientation of catalytic and reactive moieties in asymmetric autocatalysis.3

We have been studying the origin of homochirality by using asymmetric autocatalysis. Chiral inorganic crystal, chiral isotopomers,4 chiral crystals composed of achiral organic compounds, circularly polarized light (CPL), enantiotopic face of achiral mineral, i.e., gypsum,5 act as chiral triggers in asymmetric autocatalysis. Pyrimidyl alkanol of the corresponding absolute configuration with those of chiral triggers was obtained.

 

References

1. K. Soai, T. Shibata, H. Morioka, K. Choji, Nature, 1995, 378, 767-768.

2. K. Soai, T. Kawasaki, A. Matsumoto, Acc. Chem. Res., 2014, 47, 3643-3654.

3. T. Kawasaki, Y. Ishikawa, Y. Minato, T. Otsuka, S. Yonekubo, I. Sato, T. Shibata, A. Matsumoto, K. Soai, Chem. - A Eur. J., 2017, 23, 282-285.

4. A. Matsumoto, H. Ozaki, S. Harada, K. Tada, T. Ayugase, H. Ozawa, T. Kawasaki and K. Soai, Angew. Chem. Int. Ed., 2016, 55, 15246–15249.

5. A. Matsumoto, Y. Kaimori, M. Uchida, H. Omori, T. Kawasaki, K. Soai, Angew. Chem. Int. Ed., 2017, 56, 545-548.