[Problems] The present invention provides a superior production method and a superior purification method of compounds effective for the treatment or prophylaxis of pathology showing involvement of uric acid, such as hyperuricemia, gouty tophus, acute gouty arthritis, chronic gouty arthritis, gouty kidney, urolithiasis, renal function disorder, coronary artery disease, ischemic heart disease and the like. [Means] A compound represented by the following formula [2] or a pharmaceutically acceptable salt thereof can be produced by reacting a compound represented by the following formula [3] or a salt thereof with a compound represented by the following formula [4], a salt thereof or a reactive derivative thereof. Moreover, crystallization of a compound represented by the formula [2] can be performed with industrially superior workability, and high quality crystals of a compound represented by the formula [2] can be obtained. wherein each symbol is as defined in the description.