Abstract: The present invention relates to a method for producing a nucleoside derivative represented by formula (2), comprising the step of reducing a nucleoside of formula (1) in the presence of a noble metal catalyst comprising a carrier and a noble metal supported thereby, selected from the group consisting of (A) a homogeneously supported catalyst where the specific surface area of the noble metal is 95.0 m2/g or more and the particle size of the noble metal is 4.3 nm or less, and (B) a surface-loaded catalyst where the specific surface area of the noble metal is 56.0 m2/g or more and the particle size of the noble metal is 8.0 nm or less, wherein R1 is hydrogen or a protective group, R2 is NH2 or OH, R3 is an acyl group, and X is a chlorine or bromine atom. According to the present invention, the yield can be made equal even when the amount of catalyst is smaller than that used for the conventional products.

Abstract: There is provided methods for producing nateglinide crystals, which comprises the steps of adding an acid(s) to a reaction mixture containing nateglinide to make it acidic, the reaction mixture being obtained by reacting trans-4-isopropylcyclohexylcarbonyl chloride with D-phenylalanine in a mixed solvent of ketone solvent and water in the presence of an alkali; and then adjusting the temperature of the mixture to 58° C. to 72° C. and the concentration of ketone solvent to more than 8 wt % and less than 22 wt % to conduct precipitation of nateglinide crystals. This producing method is the industrially beneficial methods for crystallization of nateglinide.

Abstract: The present invention discloses methods for producing a carboxylic acid chloride compound which comprises the step of reacting an alkyl-substituted cyclohexyl carboxylic acid with a chlorinating agent in the presence of a specific urea compound. According to this invention, it is possible to produce a carboxylic acid chloride compound which has high reaction speed, and whose product has high purity or high yield. Thus produced carboxylic acid chloride compound is useful as an intermediate for producing D-phenylalanine derivatives which are used as agents for treating diabetes.

Abstract: There is provided methods for producing nateglinide crystals, which comprises the steps of adding an acid(s) to a reaction mixture containing nateglinide to make it acidic, the reaction mixture being obtained by reacting trans-4-isopropylcyclohexylcarbonyl chloride with D-phenylalanine in a mixed solvent of ketone solvent and water in the presence of an alkali; and then adjusting the temperature of the mixture to 58° C. to 72° C. and the concentration of ketone solvent to more than 8 wt % and less than 22 wt % to conduct precipitation of nateglinide crystals. This producing method is the industrially beneficial methods for crystallization of nateglinide.

Abstract: The present invention relates to a method for producing a nucleoside derivative represented by formula (2), comprising the step of reducing a nucleoside of formula (1) in the presence of a noble metal catalyst comprising a carrier and a noble metal supported thereby, selected from the group consisting of (A) a homogeneously supported catalyst where the specific surface area of the noble metal is 95.0 m2/g or more and the particle size of the noble metal is 4.3 nm or less, and (B) a surface-loaded catalyst where the specific surface area of the noble metal is 56.0 m2/g or more and the particle size of the noble metal is 8.0 nm or less, wherein R1 is hydrogen or a protective group, R2 is NH2 or OH, R3 is an acyl group, and X is a chlorine or bromine atom. According to the present invention, the yield can be made equal even when the amount of catalyst is smaller than that used for the conventional products.

Abstract: There is provided methods for producing nateglinide crystals, which comprises the steps of adding an acid(s) to a reaction mixture containing nateglinide to make it acidic, the reaction mixture being obtained by reacting trans-4-isopropylcyclohexylcarbonyl chloride with D-phenylalanine in a mixed solvent of ketone solvent and water in the presence of an alkali; and then adjusting the temperature of the mixture to 58° C. to 72° C. and the concentration of ketone solvent to more than 8 wt % and less than 22 wt % to conduct precipitation of nateglinide crystals. This producing method is the industrially beneficial methods for crystallization of nateglinide.

Abstract: There is provided methods for producing nateglinide crystals, which comprises the steps of adding an acid(s) to a reaction mixture containing nateglinide to make it acidic, the reaction mixture being obtained by reacting trans-4-isopropylcyclohexylcarbonyl chloride with D-phenylalanine in a mixed solvent of ketone solvent and water in the presence of an alkali; and then adjusting the temperature of the mixture to 58° C. to 72° C. and the concentration of ketone solvent to more than 8 wt % and less than 22 wt % to conduct precipitation of nateglinide crystals. This producing method is the industrially beneficial methods for crystallization of nateglinide.

Abstract: There is provided methods for producing nateglinide crystals, which comprises the steps of adding an acid(s) to a reaction mixture containing nateglinide to make it acidic, the reaction mixture being obtained by reacting trans-4-isopropylcyclohexylcarbonyl chloride with D-phenylalanine in a mixed solvent of ketone solvent and water in the presence of an alkali; and then adjusting the temperature of the mixture to 58° C. to 72° C. and the concentration of ketone solvent to more than 8 wt % and less than 22 wt % to conduct precipitation of nateglinide crystals. This producing method is the industrially beneficial methods for crystallization of nateglinide.

Abstract: Stable crystals of N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine may be produced by treating this compound with a solvent at a temperature of at least 10.degree. C. and forming crystals in the solvent at a temperature of at least 10.degree. C. For example, crystals may be formed by crystallization out of solution, or may be formed from solid particles of the compound suspended in a solvent. Crystals formed in this way have different melting point, infra red spectrum and X-ray diffraction patterns from previously known forms of the compound and have enhanced processability, eg. stability to grinding.

Abstract: Stable crystals of N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine may be produced by treating this compound with a solvent at a temperature of at least 10.degree. C. and forming crystals in the solvent at a temperature of at least 10.degree. C. For example, crystals may be formed by crystallization out of solution, or may be formed from solid particles of the compound suspended in a solvent. Crystals formed in this way have different melting point, infra red spectrum and X-ray diffraction patterns from previously known forms of the compound and have enhanced processability, e.g., stability to grinding.

Abstract: A crude 2',3'-dideoxynucleoside compound is purified by extracting with an organic solvent, or crystallizing, the 2',3'-dideoxynucleoside compound from a basic aqueous solution having a pH of not less than 12 containing the same. In another embodiment of purification a basic aqueous solution having a pH of not less than 11 of a crude 2',3'-dideoxynucleoside derivative is brought into contact with a nonpolar porous resin, whereby the derivative is adsorbed on the resin, and then the thus adsorbed derivative is desorbed with an aqueous alcoholic solution.2',3'-Dideoxynucleoside compounds which have utility as anti-AIDS drugs or anti-virus drugs can be isolated and purified in high purity and in high yield from their crude products containing impurities.

Abstract: The methyl ester of .alpha.-L-aspartyl-L-phenylalanine may be obtained in high yields directly from a reaction solution which contains N-protected- or unprotected-.alpha.-L-aspartyl-D-phenylalanine (or its methyl ester derivative), and .alpha.-L-aspartyl-L-phenylalanine methyl ester by selective crystallization of the .alpha.-L-aspartyl-L-phenylalanine methyl ester hydrochloride from an aqueous solution containing N-protected- or unprotected-L-aspartyl-L-phenylalanine and/or its methyl ester derivative and N-protected- or unprotected-L-aspartyl-D-phenylalanine and/or its methyl ester derivative, hydrochloric acid, and methanol, with or without stirring.

Abstract: This invention is directed to provide a method for obtaining .alpha.-L-aspartyl-L-phenylalanine selectively in high yields. Diffusion dialysis with an ion exchange membrane is used to decrease hydrochloric acid concentration of a mixed solution containing hydrochloric acid and one or more of four .alpha.-L-aspartyl-L-phenylalanine derivatives, i.e., .alpha.-L-aspartyl-L-phenylalanine methyl ester, .alpha.-L-aspartyl-L-phenylalanine, .alpha.-L-aspartyl-L-phenylalanine-.beta.-methyl ester and .alpha.-L-aspartyl-L-phenylalanine dimethyl ester. The resultant solution is concentrated, to which a base is added for neutralization. Subsequently, .alpha.-L-aspartyl-L-phenylalanine is crystallized and isolated.

Abstract: A method for producing an .alpha.-aspartylphenylalanine derivative represented by formula (2), which comprises reacting a .beta.-aspartylphenylalanine derivative represented by formula (1): ##STR1## with a basic compound in an alcohol solvent in the presence of a hydroxide, sulfate, chloride, carbonate or acetate of an element selected from the group consisting of zinc, copper, nickel, magnesium, aluminum, iron, tin, silicon and titanium, wherein R.sub.1 and R.sub.2 represent hydrogen or an alkyl group having 1 to 4 carbon atoms.

Abstract: A method for purifying aspartic acid comprising suspending aspartic acid crystals containing chloride ion impurities in an aqueous solution at a temperature of 50.degree. C. or higher, followed by separating the purified aspartic acid crystals, is disclosed.

Abstract: An imide of the formula: ##STR1## where R.sub.1 is hydrogen or C.sub.1-4 alkyl.

Abstract: A method for producing .alpha.-L-aspartyl-L-phenylalanine dimethyl ester, which comprises reacting 3-benzyl-6-carboxymethyl-2,5-diketopiperazine or methyl ester thereof in a methanolic solvent substantially free from water in the presence of a strong acid.

Abstract: A method for the production of N-carbobenzoxy-.alpha.-L-aspartyl-L-phenylalanine methyl ester characterized by the reaction of L-phenylalanine methyl ester with fine N-carbobenzoxy-L-aspartic anhydride crystals, is disclosed.

Abstract: The invention relates to a process for producing N-protected-.alpha.L-aspartyl-L-phenylalanine methyl ester, which comprises esterifying L-phenylalanine with methanol in the presence of a strong acid catalyst, adding, to the resulting solution, an aqueous alkaline solution to neutralize the acid catalyst and a water-immiscible organic solvent to extract the free L-phenylalanine methyl ester thus formed, collecting the organic layer, and reacting the L-phenylalanine methyl ester dissolved in said collected organic layer with N-protected-L-aspartic anhydride.

Abstract: A process for producing an .alpha.-L-aspartyl-L-phenylalanine lower alkyl ester or its hydrochloride which comprises (a) treating an L-N-(1-methyl-2-lower aliphatic acylvinyl or 1-methyl-2-lower alkoxycarbonylvinyl)-aspartic acid or an alkali metal salt thereof with a dehydrating agent in an organic solvent containing an acid, (b) reacting the solution resulting from such treatment with an L-phenylalanine lower alkyl ester and (c) treating the resulting reaction mixture with water or an aqueous acid solution to remove the 1-methyl-2-lower aliphatic acylvinyl or 1-methyl-2-lower alkoxycarbonylvinyl group from the L-N-(1-methyl-2-lower aliphatic acylvinyl or 1-methyl-2-lower alkoxycarbonylvinyl)-aspartyl-L-phenylalanine lower alkyl ester is disclosed, along with L-N-(1-methyl-2-acetylvinyl)-aspartic acid anhydride.