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Updated: Dec 23, 2025

Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
An uncommon use of irradiated flavins: Brønsted acid catalysis
Yukihiro Arakawa1, Tomohiro Mihara1, Hiroki Fujii1
1Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan. arakawa.yukihiro@tokushima-u.ac.jp imada@tokushima-u.ac.jp.
Abstract:
We present that thioacetalization of aldehydes can be induced by blue light irradiation in the presence of a catalytic amount of riboflavin tetraacetate (RFTA) under aerobic conditions. Several control experiments have suggested that the reaction is more likely to be catalyzed by acidic species generated in situ upon light irradiation. We have proposed that single electron transfer from a thiol (RSH) to the excited state of RFTA can take place to give a one-electron oxidized thiol (RSH+˙) and the one-electron reduced RFTA (RFTA-˙), which can be trapped by molecular oxygen to be stabilized as Brønsted acids including the protonated RFTA-˙ (RFTAH˙). Finally, we have demonstrated that such acidic species can be prepared in advance as a solution and used as Brønsted acid catalysts for not only thioacetalization but also Mannich-type reactions.
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