Abstract: An object of the present invention is to provide a high-purity crystal of a compound represented by formula (1a) that is an activated blood coagulation factor X (FXa) inhibitor. Solution: High-purity crystals of a compound represented by the following formula (1a): wherein, with regard to the content of impurities, the maximum content of any one type of impurity is 0.03% or less, and the total content of impurities is 0.13% or less, and wherein the high-purity crystals are obtained by a step of dissolving crystals in a solvent and then recrystallizing them.

Abstract: The present invention provides a novel process for preparing a substituted aromatic compound such as an aromatic halo compound or a salt thereof through a transformation reaction of an aromatic diazonium salt from an aromatic amino compound at stable high yields utilizing a novel Sandmeyer-like reaction using a nitroxide radical compound as a reaction catalyst.

Abstract: The problem to be solved is to provide an important intermediate for production of an FXa inhibitor. The solution thereto is a method for industrially producing a compound (1) or a compound (4), comprising: [Step 1]: adding a quaternary ammonium salt and a metal azide salt to water to prepare an aqueous solution of an azidification reagent complex comprising quaternary ammonium salt-metal azide salt, and subsequently dehydrating the aqueous solution using an aromatic hydrocarbon solvent to form a mixed solution of the azidification reagent complex comprising quaternary ammonium salt-metal azide salt and the aromatic hydrocarbon solvent with a water content of 0.2% or less; and [Step 2]: adding, to the mixed solution prepared in [Step 1], a compound (2) wherein L represents a leaving group.

Abstract: The problem to be solved is to produce, at high yields with high purity, anhydrous crystals of a compound represented by formula (1) that is an important intermediate for preparation of FXa inhibitor compound (X) or a pharmacologically acceptable salt thereof, or a hydrate thereof. The solution thereto is an industrial preparation process that provides, with high purity, anhydrous crystals of a compound represented by the following formula (1), which is an intermediate for the production of FXa inhibitor compound (X) or a pharmacologically acceptable salt thereof, or a hydrate thereof, wherein Boc represents a tert-butoxycarbonyl group.

Abstract: The problem to be solved is to produce, at high yields with high purity, anhydrous crystals of a compound represented by formula (1) that is an important intermediate for preparation of FXa inhibitor compound (X) or a pharmacologically acceptable salt thereof, or a hydrate thereof. The solution thereto is an industrial preparation process that provides, with high purity, anhydrous crystals of a compound represented by the following formula (1), which is an intermediate for the production of FXa inhibitor compound (X) or a pharmacologically acceptable salt thereof, or a hydrate thereof, wherein Boc represents a tert-butoxycarbonyl group.

Abstract: The problem to be solved is to provide an important intermediate for production of an FXa inhibitor. The solution thereto is a method for industrially producing a compound (1) or a compound (4), comprising: [Step 1]: adding a quaternary ammonium salt and a metal azide salt to water to prepare an aqueous solution of an azidification reagent complex comprising quaternary ammonium salt-metal azide salt, and subsequently dehydrating the aqueous solution using an aromatic hydrocarbon solvent to form a mixed solution of the azidification reagent complex comprising quaternary ammonium salt-metal azide salt and the aromatic hydrocarbon solvent with a water content of 0.2% or less; and [Step 2]: adding, to the mixed solution prepared in [Step 1], a compound (2) wherein L represents a leaving group.