A Thioxanthone Sensitizer with a Chiral Phosphoric Acid Binding Site: Properties and Applications in Visible Light-Mediated Cycloadditions

Franziska Pecho, You Quan Zou, Johannes Gramüller, Tadashi Mori, Stefan M. Huber, Andreas Bauer, Ruth M. Gschwind, Thorsten Bach

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

A chiral phosphoric acid with a 2,2’-binaphthol core was prepared that displays two thioxanthone moieties at the 3,3’-position as light-harvesting antennas. Despite its relatively low triplet energy, the phosphoric acid was found to be an efficient catalyst for the enantioselective intermolecular [2+2] photocycloaddition of β-carboxyl-substituted cyclic enones (e.r. up to 93:7). Binding of the carboxylic acid to the sensitizer is suggested by NMR studies and by DFT calculations to occur by means of two hydrogen bonds. The binding event not only enables an enantioface differentiation but also modulates the triplet energy of the substrates.

Original languageEnglish
Pages (from-to)5190-5194
Number of pages5
JournalChemistry - A European Journal
Volume26
Issue number23
DOIs
StatePublished - 21 Apr 2020

Keywords

  • enantioselectivity
  • hydrogen bonds
  • organocatalysis
  • photochemistry
  • sensitizers

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