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Catalytic Enantioselective 6π Photocyclization of Acrylanilides.

Benjamin A JonesPearse SolonMihai V PopescuJi-Yuan DuRobert S PatonMartin D Smith
Published in: Journal of the American Chemical Society (2022)
Controlling absolute stereochemistry in catalytic photochemical reactions is generally challenging owing to high rates of background reactivity. Successful strategies broadly rely on selective excitation of the reaction substrate when associated with a chiral catalyst. Recent studies have demonstrated that chiral Lewis acid complexes can enable selective energy transfer from a photosensitizer to facilitate enantioselective triplet state reactions. Here, we apply this approach to the enantioselective catalysis of a 6π photocyclization through the design of an iridium photosensitizer optimized to undergo energy transfer to a reaction substrate only in the presence of a chiral Lewis acid complex. Among a group of iridium(III) sensitizers, enantioselectivity and yield closely correlate with photocatalyst triplet energy within a narrow window enabled by a modest reduction in substrate triplet energy upon binding a scandium/ligand complex. These results demonstrate that photocatalyst tuning offers a means to suppress background reactivity and improve enantioselectivity in photochemical reactions.
Keyphrases
  • energy transfer
  • visible light
  • photodynamic therapy
  • ionic liquid
  • quantum dots
  • capillary electrophoresis
  • highly efficient
  • amino acid
  • structural basis
  • binding protein
  • dna binding