摘要:
A process for optical resolution of a racemic substituted benzylamine is provided that involves reacting the racemic substituted benzylamine in a solvent with an optically active N-acyl-phenylalanine, -aspartic acid, or -glutamic acid, and separating the diastereomers formed by making use of the difference in the mutual solubilities of the two diastereomer salts which are generated therein.
摘要:
Novel aspartyldipeptideamide derivatives of formula (I): L--Asp--X--NH--C*HR.sub.1 R.sub.2 and salts thereof, wherein X is a D-.alpha.-amino acid residue or a DL-.alpha.-amino acid residue selected from the group consisting of D-alanine, D-.alpha.-aminobutyric acid, D-norvaline, D-valine, D-norleucine, D-leucine, D-isoleucine, D-alloisoleucine, D-t-leucine, D-serine, D-O-methylserine, D-threonine, D-O-methylthreonine, D-allothreonine, D-O-methylallothreonine, D-phenyl glycine and D- or DL furyl glycine, or X is a cyclic or non-cyclic .alpha., .alpha.-dialkyl amino acid residue having 3 to 6 carbon atoms; R.sub.1 is a linear or branched alkyl group having 1 to 6 carbon atoms or an alkoxymethyl group having 2 to 7 carbon atoms in the alkoxy portion; R.sub.2 is a phenyl group having a substituent in its 2, 3- or 4-position selected from the group consisting of F, Cl, Br, I, a hydroxy group, a linear or branched alkoxy group having 1 to 6 carbon atoms, a cyano group, a nitro group, an acetyl group, an amino group and an acetylamino group, or R.sub.2 is a phenyl group having a methylenedioxy group, a trimethylene group or a tetramethylene group in its 2, 3- or 3, 4- position or R.sub.2 is a 2, 3- or 4-pyridyl group, a 2- or 3-furyl group or a 2- or 3-thienyl group; the configuration of C* in formula (I) is (S) or (RS) when R.sub.1 is a linear or branched alkyl group; (R), (S), or (RS) when R.sub.1 is an alkoxymethyl group; and in formula (I), L-Asp and X are .alpha.-bonded.
摘要:
The present invention provides crystals of L-phenylalanine monomethyl sulfate which have low solubility compared to L-tyrosine and D-phenylalanine. The L-phenylalanine monomethylsulfate crystals are obtained by subjecting a solution containing monomethyl sulfuric acid and phenylalanine to crystallization.Further, the present invention also provides a process for recovering L-phenylalanine from a water layer by neutralizing the esterified reaction, extracting an ester of L-phenylalanine therefrom with an organic solvent, and recovering remaining L-phenylalanine in the water layer as L-phenylalanine monomethylsulfate. L-phenylalanine monomethyl sulfate is obtained by esterifying L-phenylalanine and methanol in the presence of sulfuric acid, neutralizing the esterified solution with a base in the presence of water, extracting the produced L-phenylalanine methyl ester from the neutralized solution with an organic solvent, and then crystallized the resultant water layer under acidic condition.
摘要:
A process for improving the yield of crystallization of L-phenylalanine monomethyl sulfate from an aqueous solution containing L-phenylalanine and monomethyl sulfate, by adding an effective crystallization improving amount of a salt of an inorganic or organic acid with an alkali metal, an alkaline earth metal or ammonium, to the aqueous solution.
摘要:
The present invention provides crystals of L-phenylalanine monomethyl sulfate which have low solubility compared to L-tyrosine and D-phenylalanine. The L-phenylalanine monomethylsulfate crystals are obtained by subjecting a solution containing monomethyl sulfuric acid and phenylalanine to crystallization.Further, the present invention also provides a process for recovering L-phenylalanine from a water layer by neutralizing the esterified reaction, extracting an ester of L-phenylalanine therefrom with an organic solvent, and recovering remaining L-phenylalanine in the water layer as L-phenylalanine monomethylsulfate. L-phenylalanine monomethyl sulfate is obtained by esterifying L-phenylalanine and methanol in the presence of sulfuric acid, neutralizing the esterified solution with a base in the presence of water, extracting the produced L-phenylalanine methyl ester from the neutralized solution with an organic solvent, and then crystallized the resultant water layer under acidic condition.
摘要:
A method for preparing an amino acid ester with sulfuric acid as the catalyst in high yield, in which a mixture of amino acid, sulfuric acid and an alcohol is heated while adding the alcohol as a liquid or gas to the reaction mixture and alcohol from the reaction mixture is distilled off.
摘要:
A method is disclosed for the production of .alpha.-APM.HCl by treating an F-.alpha.-AP derivative with a mixed solvent of methanol, hydrochloric acid and water, wherein the solubility of .alpha.-APM.HCl is lowered to increase the separation yield thereof.
摘要:
A method for converting .beta.-aspartylphenylalanine derivative (1) to .alpha.-aspartylphenylalanine derivatives (2) and (3), said derivatives having the following structures: ##STR1## which comprises: reacting said .beta.-aspartylphenylalanine derivative (1) at a temperature of from 0.degree. to 200.degree. C. for a time period of from 30 minutes to 80 hours, in a C.sub.1 to C.sub.4 alcohol solvent with or without stirring, wherein R and R' represent hydrogen or an alkyl group having from 1 to 4 carbon atoms.
摘要:
The masking N-formyl group of an N-formyl-amino acid ester or an N-formyl-peptide ester having a free carboxyl group is removed without major side reactions when the ester is contacted with a strong acid in a mixture of water and a specific organic solvent such as methyl ethyl ketone or acetonitrile. This method is specifically applicable to the production of L-aspartyl amino acid lower alkyl esters which are known as low calorie sweeteners.
摘要:
The masking N-formyl group of an N-formyl-amino acid ester or N-formyl-peptide ester is removed without major side reactions when the ester is reacted in an inert liquid medium with hydroxylamine of which at least 70% is present in the form of a salt with a strong acid, the remainder, if any, being present as the free base or the salt of a weak acid.