PRODUCTION METHOD FOR 3, 3-DIMETHYL-3, 4-DIHYDRO-1H-QUINOXALINE-2-ONE DERIVATIVE AND INTERMEDIATE FOR SAID PRODUCTION METHOD 33341H2

An obj ect is to provide a novel production method suitable for industrial production of a 3,3-dimethyl-3,4-dihydro-1H-quinoxalin-2-one derivative and a synthetic intermediate for the method. Provided is a method for producing a compound represented by formula (1): wherein R 1 represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted cycloalkyl group, or an optionally substituted aryl group, R 2 represents a hydrogen atom, an optionally substituted alkyl group, a hydroxy group, or a nitrogen atom-protecting group, R 3 represents a hydrogen atom, an optionally substituted alkyl group, a hydroxy group, or a nitrogen atom-protecting group, and X represents a hydroxy group or a leaving group, or a salt thereof, the method comprising the steps of: reacting a compound represented by formula (2): wherein R 1 , R 2 , and X are the same as defined in formula (1), R 4 represents an optionally substituted alkyl group, an optionally substituted cycloalkyl group, or an optionally substit