Reduced Molecular Flavins as Single-Electron Reductants after Photo-Excitation

17 December 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Flavoenzymes mediate a multitude of chemical reactions and are catalytically active both in different oxidation states and in covalent adducts with reagents. The transfer of such reactivity to the organic laboratory using simplified molecular flavins is highly desirable and such applications in (photo-)oxidation reactions are already established. However, molecular flavins have not been used for the reduction of organic substrates yet, although this activity is known and well-studied for DNA photolyase enzymes. We report a catalytic method using reduced, molecular flavins as photo-reductants and γ-terpinene as sacrificial reductant. Additionally, we present our design for air-stable, reduced flavin catalysts, which is based on a conformational bias strategy and circumvents the otherwise rapid reduction of O2 from air. Using our catalytic strategy, we were able to replace super-stoichiometric amounts of the rare-earth reductant SmI2 in a 5-exo-trig cyclization of substituted barbituric acid derivatives. Such flavin-catalyzed reductions are anticipated to be of broad applicability and their straightforward synthesis indicates future use in stereo- as well as site-selective transformations.


Organic Photochemistry
Biomimetic Reactions
Flavin Catalysis
Single-Electron Reductions

Supplementary materials

Supporting Information
The Supporting Information (PDF) contains experimental procedures, analytical data for all new compounds, additional experiments, and NMR data.


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