METHOD FOR PRODUCING 6-DISUBSTITUTED AMINO-7-DEAZAXANTHINE COMPOUND

PROBLEM TO BE SOLVED: To provide a method for producing 6-disubstituted amino-7-deazaxanthine compound useful as an intermediate of therapeutic agents for diabetes mellitus, etc.; its intermediate; and a method for producing 6-disubstituted amino-5-benzyl-7-deazaxanthine using the compound.SOLUTION: This method for producing the compound expressed by formula (4) comprises: reacting a compound expressed by formula (1) (in formula, Rand Rare the same or different and each represents a 1-6C alkyl or the like) with secondary amines and ortho-formate to obtain a compound expressed by formula (3) (where Rrepresents a 1-6C alkyl or the like, and Rrepresents a 1-6C alkyl or the like); and reducing the compound expressed by formula (3) using sodium dithionite, etc. There is disclosed also a method for producing a compound expressed by formula (6) by reacting the compound expressed by formula (4), protected if needed, with benzyl alcohols in the presence of a phosphine compound, etc., and performing deprotection reaction, if needed.