Process for preparing β-amino-α-hydroxycarboxamides

A process for preparing enantiomerically enriched compounds of general formula (I)

• in which
• R1, R2, R3, R4, R5 are each independently (C1-C8)-alkyl, HO—(C1-C8)-alkyl, (C2-C8)-alkoxyalkyl, (C6-C18)-aryl, (C7-19)-aralkyl, (C3-C18)-heteroaryl, (C4-C19)-heteroaralkyl, (C1-C8)-alkyl-(C6-C18)-aryl, (C1-C8)-alkyl-(C3-C18)-heteroaryl, (C3-C8)-cycloalkyl, (C1-C8)-alkyl-(C3-C8)-cycloalkyl, (C3-C8)-cycloalkyl-(C1-C8)-alkyl, or
• R4 and R5 and/or R2 and R3 together form a (C2-C8)-alkylene bridge,
• where R1, R2, R3, R4 may additionally be H and
• with the proviso that R1 is not phenyl when R4 and/or R5=H,
• said process comprising:
• a) reacting epoxycarboxamides of general formula (II)
• in which R1, R4, R5 are each as defined above,
• with ammonia or amines of the general formula (III)
• in which R2, R3 are each as defined above;
• wherein enantiomerically enriched compounds of general formula (I) are prepared using enantiomerically enriched compounds of formula (II);
• or as a second step
• b) enantioselectively crystallizing the salts of racemic diastereomerically enriched compounds of formula (I) using a chiral organic acid;
• and wherein one or more of the following conditions apply:
• i) R1 is a (C1-C8)-alkyl;
• ii) R4 is H;
• iii) R5 is a (C1-C8)-alkyl-(C3-C8)-cycloalkyl;
• iv) R5 is cyclopropyl.