Abstract
Treatment of riboflavin monophosphite, with N-bromosuccinimide, N-bromoacetamide, or bromine in aqueous acid solution oxidized it to the corresponding phosphate. Neither degradation of riboflavin moiety nor acid-catalyzed hydrolysis was observed. Addition of pyridine or sodium acetate to the reaction mixture retarded the reaction markedly. Using this reaction, isobutyl, sec-butyl, cyclohexyl, benzyl, and 2-benzyloxycarbonylaminoethyl phosphate were obtained as crystalline barium salt from the corresponding phosphites.
