Process for the preparation of enantiomeric forms of 2,3-diaminopropionic acid derivatives

A process for obtaining a compound of formula IV or a salt thereof:

• wherein
• R1 is a hydrogen atom, F, Cl, I, Br, (C1-C4)-alkyl or —CN;
• R2 is a heteroaryl residue selected from the series consisting of pyrrole, furan, thiophene, imidazole, pyrazole, oxazole, isoxazole, thiazole, isothiazole, tetrazole, 1,2,3,5-oxathiadiazole-2-oxides, triazolones, oxadiazolone, isoxazolone, oxadiazolidinedione, triazole, 3-hydroxypyrrole-2,4-diones, 5-oxo-1,2,4-thiadiazoles, pyridine, pyrazine, pyrimidine, indole, isoindole, indazole, phthalazine, quinoline, isoquinoline, quinoxaline, quinazoline, cinnoline and β-carboline, wherein the heteroaryl residue is unsubstituted or is substituted once, twice or three times, independently of each other, by substituents selected from the series consisting of (C1-C5)-alkyl, (C1-C5)-alkoxy, halogen, nitro, amino, trifluoromethyl, hydroxy, hydroxy-(C1-C4)-alkyl-, methylenedioxy, ethylenedioxy, formyl, acetyl, cyano, hydroxycarbonyl-, aminocarbonyl- and (C1-C4)-alkoxycarbonyl-, or an aryl residue selected from the series consisting of phenyl, naphthyl, biphenylyl, anthryl and fluorenyl, wherein the aryl residue is unsubstituted or is substituted once, twice or three times, independently of each other, by substituents selected from the series consisting of (C1-C5)-alkyl, (C1-C5)-alkoxy, halogen, nitro, amino, trifluoromethyl, hydroxy, hydroxy-(C1-C4)-alkyl-, methylenedioxy, ethylenedioxy, formyl, acetyl, cyano, hydroxycarbonyl-, am inocarbonyl- and (C1-C4)-alkoxycarbonyl-;
• R3 is a hydrogen atom,
• or (C1-C4)-alkyl,
• or an aryl residue selected from the series consisting of phenyl, naphthyl, biphenylyl, anthryl and fluorenyl, wherein the aryl residue is unsubstituted or is substituted, independently of each other, once, twice or three times by substituents selected from the series consisting of —NO2, —O—(C1-C4)-alkyl, F, Cl and Br,
• or —O—C(CH3)3,
• or —O—CH(R7)-aryl, wherein the aryl residue is selected from the series consisting of phenyl, naphthyl, biphenylyl, anthryl and fluorenyl and is unsubstituted or is substituted, independently of each other, once, twice or three times by substituents selected from the series consisting of —NO2, —O—CH3, F, Cl and Br, and wherein R7 is a hydrogen atom or (C1-C4)-alkyl;
• and
• R5 is —NH2, —N(H)—R6 or —N(R6)2, wherein R6 is (C1-C4)-alkyl or aryl, wherein the aryl residue is selected from the series consisting of phenyl, naphthyl, biphenylyl, anthryl and fluorenyl;
• said process comprising:
• a) mixing a compound of formula II:
• wherein R1, R2 and R3 are defined as in the compound of formula IV, in an organic solvent or a mixture of organic solvents with an enantiomerically pure auxiliary to form a salt composed of enantiomerically pure auxiliary and compound of formula I:
• wherein R1, R2 and R3 are defined as in the compound of formula IV;
• b) separating the salt composed of enantiomerically pure auxiliary and compound of formula I, by fractional crystallization;
• c) isolating the compound of formula I from the salt composed of enantiomerically pure auxiliary and compound of formula I;
• and
• d) converting the resulting compound of formula I with ammonia or an amine of the formula H2N—R6 or HN(R6)2, wherein R6 is (C1-C4)-alkyl or aryl, wherein the aryl residue is selected from the series consisting of phenyl, naphthyl, biphenylyl, anthryl and fluorenyl, into the compound of formula IV or a salt thereof.