Unlocking flavin photoacid catalysis through electrophotochemistry

Area of Science:

• Organic Chemistry
• Photocatalysis
• Green Chemistry

Background:

• Molecular flavins are established photocatalysts with diverse electron and hydrogen transfer capabilities.
• Their potential as photoacids, however, remains largely unexplored in catalytic applications.

Purpose of the Study:

• To investigate the photoacid properties of flavins using electrochemistry.
• To demonstrate novel catalytic mechanisms and expand the synthetic utility of flavins.

Main Methods:

• Electrophotochemistry was employed to generate super-oxidized flavinium species from flavin quinones.
• The reactivity of these electro-generated flavinium salts was assessed in proton-transfer and radical-mediated reactions.

Main Results:

• Super-oxidized flavinium photoacids were successfully generated, facilitating acid-catalyzed transformations.
• These flavinium species also produced hydroxyl radicals, enabling sp³C-H functionalization via hydrogen-atom abstraction.
• A bimodal reactivity, encompassing both photoacid and radical-generating pathways, was observed.

Conclusions:

• Electrocatalysis unlocks unprecedented photoacid and radical-generating capabilities in flavins.
• This expands the versatility of flavins as catalysts for novel synthetic chemistries.
• The findings pave the way for new applications in photocatalysis and organic synthesis.