Patent ID: 6683190
Filing Date: 2004-01-27
Classification: C07C,Y02P

Abstract:
Process for preparing chiral amino acids of formula (I): in which:R1 and R2 are different and are selected from: an alkyl or haloalkyl radical containing from 1 to 6 carbon atoms in a linear or branched chain; an alkoxyalkyl, alkylthioalkyl, alkylsulphonylalkyl, monoalkylaminoalkyl, alkenyl or alkynyl radical containing from 2 to 6 carbon atoms in a linear or branched chain; a dialkylaminoalkyl or cycloalkyl radical containing from 3 to 7 carbon atoms in a linear or branched chain; an aryl radical, optionally substituted by from 1 to 3 individually selected R6 groups; and an arylalkyl, aryloxyalkyl, arylthioalkyl or arylsulphonylalkyl radical; or else R1 and R2, together with the carbon atom to which they are attached on the ring, form a carbocycle or a heterocycle containing from 5 to 7 atoms, including these rings being fused with a phenyl optionally substituted by from 1 to 3 individually selected R6 groups; R6 represents a radical selected from: a halogen atom; an alkyl, haloalkyl, alkoxy, haloalkoxy, alkylthio, haloalkylthio or alkylsulphonyl radical containing from 1 to 6 carbon atoms; a cycloalkyl, halocycloalkyl, alkenyloxy, alkynyloxy, alkenylthio, alkynylthio radical containing from 3 to 6 carbon atoms; a nitro or cyano group; an amino radical optionally mono- or disubstituted by an alkyl or acyl radical containing from 1 to 6 carbon atoms or alkoxycarbonyl radical containing from 2 to 6 carbon atoms; and a phenyl, phenoxy or pyridyloxy radical, these radicals being optionally substituted by from 1 to 3 identical or different R7 groups; and R7 represents a radical selected from: a fluorine, chlorine, bromine or iodine atom; a linear or branched alkyl radical containing from 1 to 6 carbon atoms; a linear or branched alkoxy or alkylthio radical containing from 1 to 6 carbon atoms; a linear or branched haloalkoxy or haloalkylthio radical containing from 1 to 6 carbon atoms; a nitrile radical; and a nitro radical, said process comprising the steps of: (A) dissolving a racemic hydantoin of formula (II): in a basic medium used in an amount of from 0.2 to 0.8 equivalent of base relative to the amount of said racemic hydantoin;(B) adding an enantiomeric resolving agent in an amount of from 0.2 to 1.0 equivalent of resolving agent relative to the amount of said racemic hydantoin; (C) separating the resolving agent from the reaction mixture; and (D) hydrolysing the reaction mixture in a basic medium in order to liberate the basic salt of the desired chiral amino acid, which process is conducted in a water/co-solvent mixture.