NEW MATERIAL:A compound of formulaI(R1 is H, lower alkyl, phenyl, benzyl, pyridyl, which may have substituents on their nuclei, ribityl which can have acetyl, phosphonyl or adenosylphosphate groups; R2WR7 are H, lower alkyl, phenyl, benzyl, pyridyl, each of which may have substituents on their nuclei, or polymer bonded through intermediate groups).

EXAMPLE: 2,4-Dimethylpyrido[5,6-h](10-methyl)isoalloxazine.

USE: A component of oxidation catalyst: it increases the electron deficit degree in flavin molecule.

PREPARATION: The condensation reaction between 7,8-diamino-quinoline of formula II and an alloxan of formula III is carried out in the presence of an acid catalyst such as toluenesulfonic acid to give the compound of formulaI.