Abstract: The present invention relates to a process for producing an N-carbamoyl-tert-leucine, characterized in mixing tert-leucine with an isocyanic acid compound while a pH of the mixture is kept at not less than 8.0 and not more than 13.5, wherein an amount of the isocyanic acid compound is not less than 0.9 times by mole and not more than 1.1 times by mole relative to an amount of the tert-leucine. According to the present invention, it becomes possible to easily produce an N-carbamoyl-tert-leucine with high efficiency, while the generation of by-products such as a dipeptide-like compound and a urea compound is prevented.

Abstract: The present invention relates to a process for producing an N-carbamoyl-tert-leucine, characterized in mixing tert-leucine with an isocyanic acid compound while a pH of the mixture is kept at not less than 8.0 and not more than 13.5, wherein an amount of the isocyanic acid compound is not less than 0.9 times by mole and not more than 1.1 times by mole relative to an amount of the tert-leucine. According to the present invention, it becomes possible to easily produce an N-carbamoyl-tert-leucine with high efficiency, while the generation of by-products such as a dipeptide-like compound and a urea compound is prevented.

Abstract: The present invention provides a process for simply producing an optically active 2-thiomethyl-3-phenylpropionic acid derivative useful as an intermediate for medicines from inexpensive raw materials. An optically active 2-hydroxymethyl-3-phenylpropionic acid ester derivative which can be relatively easily obtained by asymmetric reduction reaction with an enzyme is cyclized to an optically active P-lactone derivative which is then reacted with a sulfur compound to produce an optically active 2-thiomethyl-3-phenylpropionic acid derivative in high yield.

Abstract: The present invention is to efficiently and simply prepare an optically active 7-substituted-2-aminotetralin with industrial advantage. In the process, a 7-substituted-2-tetralone or its bisulfite adduct is reduced with a microorganism to an optically active 7-substituted-2-tetralol. Then, a sulfonyl group is introduced to the hydroxy group to form an optically active 7-substituted-2-sulfonyloxytetralin. Then, with inversion of the configuration, a nitrogen substituent is introduced using a nitrogen nucleophile to form an optically active 2,7-substituted tetralin. Furthermore, if necessary, the nitrogen substituent is converted into a non-substituted amino group. Thus, an optically active 7-substituted-2-aminotetralin or its salt is prepared.

Abstract: The present invention has an object to provide a process for easily producing optically active N-aryl-1-amino-2-propanol derivatives which are of value as pharmaceutical intermediates from inexpensive starting materials.

Abstract: The present invention has for its object to provide a practical method for the purification and isolation on a commercial scale of said compound (1) or compound (2) in good yield and with high quality. The present invention provides a purification/isolation method of a (2S,3S)-1-halo-2-hydroxy-3-N-(tert-butoxycarbonyl)amino-4-phenylbutane (1) or a (2R,3S)-1-halo-2-hydroxy-3-N-(tert-butoxycarbonyl)amino-4-phenylbutane (2) which comprises, for the purpose of removing contaminant impurity from a mixture containing at least one of said compounds (1) and (2), causing the objective compound (1) or compound (2) to be crystallized in the presence of a solvent comprised of a hydrocarbon solvent and then collecting the obtained crystals.

Abstract: The present invention provides a production method of high quality threo-1,2-epoxy-3-amino-4-phenylbutane derivatives (1) on a commercial scale in a simple, easy and efficient manner and with very high productivity, which comprises treating a threo-1-halo-2-hydroxy-3-amino-4-phenylbutane derivative (2) with a base in a polar organic solvent or a solvent composed of a polar organic solvent and water, and adding the resulting reaction mixture to water to thereby cause the resulting threo-1,2-epoxy-3-amino-4-phenylbutane derivative (1) to crystallize out.

Abstract: The present invention has for its object to provide a commercially useful, expedient and efficient method for purification and isolation of an N-protected (2S,3R)-1-halo-2-hydroxy-3-amino-4-phenylthiobutane (1) or its enantiomer, which is capable of removing the various contaminants, particularly said byproducts, whereby the problem of instability of the compound (1) or its enantiomer can be overcome and a high product yield can be insured.The present invention relates to a method of purifying and isolating an N-protected (2S,3R)-1-halo-2-hydroxy-3-amino-4-phenylthiobutane (1): ##STR1## (wherein X represents a halogen atom; one of P.sup.1 and P.sup.2 represents a hydrogen atom and the other represents an amino-protecting group, or P.sup.1 and P.sup.