Comparison of riboflavin-derived flavinium salts applied to catalytic H2O2 oxidations. Issue 21 (16th May 2018)

• Record Type: Journal Article
• Authors: Sakai, Takuya; Kumoi, Takuma; Ishikawa, Tatsuro; Nitta, Takahiro; Iida, Hiroki
• Is Part Of: Organic & biomolecular chemistry. Volume 16:Issue 21(2018)
• Page Start: 3999
• Page End: 4007
• Publication Date: 2018-05-16
• Subjects: Chemistry, Organic -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1039/c8ob00856f
• Languages: English
• ISSNs: 1477-0520

Abstract

Abstract : A series of flavinium salts were prepared from commercially available riboflavin, and their optical and redox properties and their catalytic activity were compared. Abstract : A series of flavinium salts, 5-ethylisoalloxazinium, 5-ethylalloxazinium, and 1, 10-ethylene-bridged alloxazinium triflates, were prepared from commercially available riboflavin. This study presents a comparison between their optical and redox properties, and their catalytic activity in H2 O2 oxidations of sulfide, tertiary amine, and cyclobutanone. Reflecting the difference between the π-conjugated ring structures, the flavinium salts displayed very different redox properties, with reduction potentials in the order of: 5-ethylisoalloxazinium > 5-ethylalloxazinium > 1, 10-ethylene-bridged alloxazinium. A comparison of their catalytic activity revealed that 5-ethylisoalloxazinium triflate specifically oxidises sulfide and cyclobutanone, and 5-ethylalloxazinium triflate smoothly oxidises tertiary amine. 1, 10-Bridged alloxazinium triflate, which can be readily obtained from riboflavin in large quantities, showed moderate catalytic activity for the H2 O2 oxidation of sulfide and cyclobutanone.