Coenzyme Models. 28. Facile Oxidation of Alcohols and Amines by 3-Hydroxy-N-methylacridinium Ion, a New NAD+ Model Compound

Article abstract of DOI:10.1021/jo00324a025

The title compound (Ac⁺OH) was synthesized for the purpose of developing a new NAD⁺ model compound which is capable of oxidizing alcohols and amines.The absorption spectrum of Ac⁺OH was similar to that of N-methylacridinium ion (Ac⁺) in the acidic pH region and to that of 5-deazaflavin in the basic pH region.The absorption spectrum of the reduced form was analogous to that of 3-aminophenol.The reduced form which was prepared by NaBH4 reduction was promptly reoxidized by molecular oxygen.With the aid of potassium tert-butoxide, Ac⁺OH oxidized benzyl alcoholand cyclohexanol to the corresponding aldehyde and ketone in almost quantitative yields.In contrast, Ac⁺ was totally useless as an oxidant under the same reaction conditions.Benzylamine was oxidized by Ac⁺ to benzaldehyde in low yields (11-24percent).On the other hand, the oxidation by Ac⁺OH occurred in good yields (82-88percent).When the reaction was carried out under an oxygen stream, the yield calculated on the basis of Ac⁺OH was enhanced up to 1800-2200percent.The results indicate that Ac⁺OH acts as an effective turnover oxidizing agent and that the 3-hydroxyl group plays a crucial role in the redox reactions occurring on the acridinium nucleus.This is the first example of the facile oxidation of alcohols and amines which mimics the catalytic behavior of NAD⁺ coenzyme.