Microenvironmental control of enantiodifferentiating photocyclization of 5-hydroxy-1,1-diphenylpentene through selective solvation

Yasuhiro Nishiyama, Takehiko Wada, Kiyomi Kakiuchi, Yoshihisa Inoue

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

For mechanistic elucidation of the photosensitized cyclization of 5-hydroxy-1,1-diphenylpentene (1), its methyl ether (4) was synthesized as an unreactive "dummy" substrate and used as a quencher of the sensitizer fluorescence to reveal the intervention of an exciplex intermediate that was unable to detect when reactive substrate 1 was used as a quencher/reactant In the enantiodifferentiating photocyclization of 1 to 2-(diphenylmethyl) tetrahydrofuran (2) sensitized by a chiral saccharide ester of 1,4-naphthalenedicarboxylate (3), the enantiomeric excess (ee) of chiral product 2 obtained in methylcyclohexane (MCH) at 25 °C was significantly enhanced from 20% to 35% upon 10-fold dilution of the sample solution by MCH, for which the reduced solvent polarity, discouraging dissociation of the intervening radical ionic exciplex, is likely to be responsible. Further attempts to microenvironmentally control the photochirogenic reaction and enhance the product's ee through selective solvation of polar cosolvent to the diastereomeric exciplex pair in nonpolar solvent were not successful probably due to the inherently high local polarity around the exciplex of saccharide-appended 3 with alcoholic substrate 1.

Original languageEnglish
Pages (from-to)400-405
Number of pages6
JournalChirality
Volume24
Issue number5
DOIs
Publication statusPublished - 2012 May

Keywords

  • enantioselectivity
  • photochirogenesis
  • photosensitization
  • solvent polarity

ASJC Scopus subject areas

  • Analytical Chemistry
  • Catalysis
  • Pharmacology
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

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