Pressure control of enantiodifferentiating photoisomerization of cyclooctenes sensitized by chiral benzenepolycarboxylates. The origin of discontinuous pressure dependence of the optical yield

Masayuki Kaneda, Asao Nakamura, Sadayuki Asaoka, Haruhiko Ikeda, Tadashi Mori, Takehiko Wada, Yoshihisa Inoue

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Pressure effects on enantiodifferentiating geometrical photoisomerizations of (Z)cyclooctene and (Z,Z)-cycloocta-1,5-diene sensitized by chiral benzene-1,2,4,5-tetracarboxylate were investigated over a pressure range of 0.1-750 MPa. Enantiomeric excesses (ee's) of the (E)- and (E,Z)-isomers obtained displayed discontinuous pressure dependencies, affording distinctly different differential activation volumes (ΔVΔ‡) for each range, indicating alteration of the enantiodifferentiation mechanism. The switching of ΔVΔ‡ occurred at essentially the same pressures of 200 and 400 MPa, which are shared by all the chiral sensitizers, irrespective of the chiral auxiliary employed. Circular dichroism spectral examinations at pressures of up to 400 MPa also revealed that the chiral sensitizers undergo discontinuous conformational changes at 200 MPa, which most likely lead to switching of the enantiodifferentiating sensitization mechanism in the exciplex intermediate.

Original languageEnglish
Pages (from-to)4435-4440
Number of pages6
JournalOrganic and Biomolecular Chemistry
Volume1
Issue number24
DOIs
Publication statusPublished - 2003 Dec 21
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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