Process for producing benzo[B][1,4]diazepine-2,4-dione compound

A process for producing a compound represented by formula (1),

• wherein each of R1, R2, R3 and R4, which may be the same or different, represents a hydrogen atom or a lower alkyl group,
• the process comprising deprotecting a protective group (R5) of a compound represented by formula (2),
• wherein R1, R2, R3 and R4 are as defined above, and R5 is a benzyl group that may be substituted by a group selected from the group consisting of lower alkyl groups, halogen atoms, cyano groups, lower alkoxy groups, nitro groups, phenyl groups and acyl groups,
• by reducing the compound represented by formula (2) in the presence of a catalytic hydrogenation reducing agent in a hydrogen atmosphere at 1 to 20 atm at −20 to 150° C.,
• wherein the catalytic hydrogenation reducing agent is at least one member selected from the group consisting of palladium black, palladium carbon, palladium hydroxide carbon, platinum carbon, platinum, platinum black, platinum oxide, copper chromite and Raney nickel.