Dehydrogenation of alcohols by pyrimido[4,5-b]quinoline-2(3H),4(10H)-diones (5-deazaflavins) as autorecycling oxidizing agents

Pyrimido[4,5-b]quinoline-2(3H),4(10H)-diones (5-deazaflavins) and related compounds oxidize alcohols under alkaline conditions in the dark to yield the corresponding carbonyl compounds, while they themselves are hydrogenated to the 1,5-dihydro-derivatives. The substituent effect in the 5-deazaflavin series was examined in terms of the oxidizing ability toward benzyl alcohol. In some cases, the benzyl alcohol oxidation by the 5-deazaflavins have been shown to recycle automatically, and a > 100% yield of benzaldehyde (based on the 5-deazaflavin) was obtained.