Photoenzymatic Generation of Unstabilized Alkyl Radicals: An Asymmetric Reductive Cyclization

Phillip D. Clayman, Todd K. Hyster

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


Flavin-dependent "ene"-reductases can generate stabilized alkyl radicals when irradiated with visible light; however, they are not known to form unstabilized radicals. Here, we report an enantioselective radical cyclization using alkyl iodides as precursors to unstabilized nucleophilic radicals. Evidence suggests this species is accessed by photoexcitation of a charge-transfer complex that forms between flavin and substrate within the protein active site. Stereoselective delivery of a hydrogen atom from the flavin semiquinone to the prochiral radical formed after cyclization provides high levels of enantioselectivity across a variety of substrates. Overall, this transformation demonstrates that photoenzymatic catalysis can address long-standing selectivity challenges in the radical literature.

Original languageEnglish (US)
Pages (from-to)15673-15677
Number of pages5
JournalJournal of the American Chemical Society
Issue number37
StatePublished - Sep 16 2020

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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