6-Methyl-7-(2-hydroxy-2-methyl-3-oxobutyl) ribolumazine (III) was synthesized by the method of Cresswell and Wood, and the product was found to be converted to riboflavin at pH 1.0, but action of the enzyme of Eremothecium ashbyii on III in vitro produced neigher riboflavin nor 6-methyl-7-hydroxyribolumazine.
