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DOI: 10.1055/s-0040-1719570
Ene-Reductase Permits Asymmetric Reductive Cyclization via Photoenzymatic Generation of Radicals
Photoenzymatic Generation of Unstabilized Alkyl Radicals: An Asymmetric Reductive Cyclization.
J. Am. Chem. Soc. 2020;
142: 15673-15677
DOI: 10.1021/jacs.0c07918
Key words
reductive cyclization - alkyl radicals - ene-reductases - photoenzymatic catalysis - asymmetric catalysis
Significance
Clayman and Hyster report a photoenzymatic generation of unstabilized alkyl radicals that subsequently undergo asymmetric 5- or 6‑exo-trig cyclizations to afford chiral esters, amides, or lactones in moderate to good yields and enantiomeric ratios. Notably, radical formation was found to be initiated by photoexcitation of charge-transfer complexes formed between alkyl iodides and flavin hydroquinone moieties (FMNhq) localized at the active site of the ene-reductase.
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Comment
Building upon initial findings on the use of ene-reductases in asymmetric photoenzymatic radical cyclizations (Science 2019, 364, 1166), the authors extended this reaction to challenging unstabilized alkyl radicals. Intriguingly, initial investigations showed that twofold cascade cyclization of dienes could also be performed, a process that, upon further investigation, might permit the selective cyclization of polyenes to give more-complex products.
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Publication History
Article published online:
17 November 2020
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