Contra-thermodynamic E → Z isomerization of cinnamamides via selective energy transfer catalysis

Marc R. Becker, Tobias Morack, Jack Robertson, Jan B. Metternich, Christian Mück-Lichtenfeld, Constantin Daniliuc, Glenn A. Burley, Ryan Gilmour

Research output: Contribution to journalArticle

Abstract

A bio-inspired, photocatalytic E → Z isomerization of cinnamides is reported using inexpensive (−)-riboflavin (vitamin B2) under irradiation at λ = 402 nm. This operationally simple transformation is compatible with a range of amide derivatives including –NR2, –NHSO2R and N(Boc)2 (up to 99:1 Z:E). Selective energy transfer from the excited state photocatalyst to the starting E-isomer ensures that directionality is achieved: The analogous process with the Z-isomer is inefficient due to developing allylic strain causing chromophore deconjugation. This is supported by X-ray analysis and Stern-Volmer photo-quenching studies. Preliminary validation of the method in manipulating the conformation of a simple model Leu-enkephalin penta-peptide is disclosed via the incorporation of a cinnamamide-based amino acid.
Original languageEnglish
Article number131198
Number of pages8
JournalTetrahedron
Early online date4 May 2020
DOIs
Publication statusE-pub ahead of print - 4 May 2020

Keywords

  • Alkene
  • catalysis
  • Energy transfer
  • Isomerization
  • Peptide

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