Abstract: Provided is an inexpensive and industrially advantageous method for preparing (3R,4S)-3-(N-substituted aminomethyl)-4-fluoropyrrolidine or an enantiomer thereof which can be an intermediate for producing pharmaceuticals. It relates to a method for preparing (3R,4S)-3-(N-substituted cyclopropylaminomethyl)-4-fluoropyrrolidine derivative or ait's enantiomer, or their salts, comprising a step of fluorinating a 4-hydroxy-3-(N-substituted aminomethyl)pyrrolidine derivative represented by the general formula (1) or an enantiomer thereof using a sulfur tetrafluoride derivative. [In the formula (1), PG represents a protective group for the amino group, and R1 represents a C1 to C6 alkyl group which may be substituted, or a C3 to C8 cycloalkyl group which may be substituted.

Abstract: It is to provide a method for efficiently producing an aminoacetylpyrrolidinecarbonitrile derivative which is useful as a DPP-IV inhibitor. It is a method for producing an aminoacetylpyrrolidinecarbonitrile derivative represented by the formula (2): (in the formula, A and R1 are as defined in the following), comprising allowing an acid to act on an aminoacetylpyrrolidinecarboxamide derivative represented by the formula (1): (in the formula, A represents CH2, CHF or CF2; and R1 represents a secondary amino group which may be substituted), and then allowing a dehydrating agent to act thereon.

Abstract: It is to provide a method for efficiently producing an aminoacetylpyrrolidinecarbonitrile derivative which is useful as a DPP-IV inhibitor. It is a method for producing an aminoacetylpyrrolidinecarbonitrile derivative represented by the formula (2): (in the formula, A and R1 are as defined in the following), comprising allowing an acid to act on an aminoacetylpyrrolidinecarboxamide derivative represented by the formula (1): (in the formula, A represents CH2, CHF or CF2; and R1 represents a secondary amino group which may be substituted), and then allowing a dehydrating agent to act thereon.

Abstract: Preparation of (S)-2-[[3-[N-[4-[(4-fluorophenoxy)phenyl]methyl]carbamoyl]-4-methoxyphenyl]methyl]butanoic acid (referred to as compound (I)) on an industrial scale lies in the finding of crystals homogeneous and excellent in the stability and the establishment of a preparative process thereof. Novel crystals of compound (I) homogeneous and excellent in the stability characterized by exhibiting the diffraction angles (2?) at at least 17.7°, 19.0° and 24.1° in the X-ray powder diffraction are provided by recrystallizing from an alcoholic solvent and purifying by acid-base treatment.

Abstract: Preparation of (S)-2-[[3-[N-[4-[(4-fluorophenoxy)phenyl]methyl]carbamoyl]-4-methoxyphenyl]methyl]butanoic acid (referred to as compound (I)) on an industrial scale lies in the finding of crystals homogeneous and excellent in the stability and the establishment of a preparative process thereof. Novel crystals of compound (I) homogeneous and excellent in the stability characterized by exhibiting the diffraction angles (2?) at at least 17.7°, 19.0° and 24.1° in the X-ray powder diffraction are provided by recrystallizing from an alcoholic solvent and purifying by acid-base treatment.

Abstract: The invention provides alkali metal salt of 5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[4-(trifluoromethyl)phenyl]methyl]benzamide and its hydrate. A method has been found, wherein, upon preparing KRP-297, the alkali metal salt of KRP-297 and its hydrate are formed in the reaction system and, after separation and purification, they are freed again from salt, thereby KRP-297 can be advantageously purified industrially for preparation.

Abstract: A homogeneous crystal having excellent stability which is suitable for the industrial-scale production of 5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[4-(trifluoromethyl)phenyl]methyl]benzamide (KRP-297). The novel crystal of KRP-297 is produced through recrystallization from an alcohol solvent. It is characterized by having diffraction angles (2&thgr;) at at least 9.7°, 15.0°, and 22.5° in X-ray powder diffractometry.

Abstract: A homogeneous crystal having excellent stability which is suitable for the industrial-scale production of 5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[4-(trifluoromethyl)phenyl]methyl]benzamide (KRP-297). The novel crystal of KRP-297 is produced through recrystallization from an alcohol solvent. It is characterized by having diffraction angles (2&thgr;) at at least 9.7°, 15.0°, and 22.5° in X-ray powder diffractometry.

Abstract: The invention provides alkali metal salt of 5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[4-(trifluoromethyl)phenyl]methyl]benzamide and its hydrate. A method has been found, wherein, upon preparing KRP-297, the alkali metal salt of KRP-297 and its hydrate are formed in the reaction system and, after separation and purification, they are freed again from salt, thereby KRP-297 can be advantageously purified industrially for preparation.