A process for the preparation of a β-amino amide compound of formula la, comprising: (i) providing a 2-nitropropionic acid derivative of formula (IIc) wherein Z is (i-1) a substituent defined by the following compound of formula (III') wherein Q is N, CH, C-CF 3, or C-phenyl, preferably N, and R 10 is H, C 1 -C 4 -alkyl or fluorinated C 1 -C 2 -alkyl, preferably trifluoromethyl, or (i-2) OH, OR 1, NR 2 R 3 or OSiR 4 R 5 R 6, wherein R 1 is C 1 -C 6 -alkyl or aryl-C 1 -C 2 -alkyl, R 2 is H, C 1 -C 4 -alkyl, arylmethyl, C 1 -C 4 -alkoxy or arylmethoxy, R 3 is H, C 1 -C 4 -alkyl or arylmethyl, and R 4, R 5 and R 6 independently are C 1 -C 4 -alkyl or phenyl, (ii) carrying out a coupling reaction (condensation) of the 2-nitropropionic acid derivative of formula (IIc) with an aldehyde of formula Ar-CHO, preferably in the presence of a base substance, wherein Ar is respectively unsubstituted or substituted phenyl, alkyl-aryl, alkoxy-aryl, and obtaining a compound of formula (VIIIa) or (Via) or (iii-1) subjecting the compound of formula (VIIIa) or (VIa) to a conversion reaction to obtain a compound of formula (IXa) by a reaction selected from the group of esterification, dehydration, reduction, hydrogenation, elimination and combinations thereof, or (iii-2) subjecting the compound of formula (VIIIa) to a reduction reaction to obtain optionally forming a salt thereof; wherein the stereogenic center marked with an * is either in - or -configuration at marked center, or it is in racemic form; (iv) if Z is as defined in (i-2), subjecting Z to structural modification, wherein the structural modification comprises steps of • converting a compound of formula (XIIIa) (if Z is other than OH) to compound of formula (XIVa), • activating the carboxylic group in the compound of formula (XIVa) and converting the activated derivative of formula (XIVa) to compound of formula (IXb) by reacting with compound of formula wherein Ar, *, Q and R 10 are as defined above yielding a β-nitro amide compound; (v) if the process optionally proceeds via (iii-1) or (iv), reducing the nitro group in compound of formula (IXa) or the reaction products of (iv) to an amino group to obtain a compound of formula la, optionally forming a salt thereof. (i) providing a 2-nitropropionic acid derivative of formula (IIc) wherein Z is (i-1) a substituent defined by the following compound of formula (III') wherein Q is N, CH, C-CF 3, or C-phenyl, preferably N, and R 10 is H, C 1 -C 4 -alkyl or fluorinated C 1 -C 2 -alkyl, preferably trifluoromethyl, or (i-2) OH, OR 1, NR 2 R 3 or OSiR 4 R 5 R 6, wherein R 1 is C 1 -C 6 -alkyl or aryl-C 1 -C 2 -alkyl, R 2 is H, C 1 -C 4 -alkyl, arylmethyl, C 1 -C 4 -alkoxy or arylmethoxy, R 3 is H, C 1 -C 4 -alkyl or arylmethyl, and R 4, R 5 and R 6 independently are C 1 -C 4 -alkyl or phenyl, (i-1) a substituent defined by the following compound of formula (III') wherein Q is N, CH, C-CF 3, or C-phenyl, preferably N, and R 10 is H, C 1 -C 4 -alkyl or fluorinated C 1 -C 2 -alkyl, preferably trifluoromethyl, or (i-2) OH, OR 1, NR 2 R 3 or OSiR 4 R 5 R 6, wherein R 1 is C 1 -C 6 -alkyl or aryl-C 1 -C 2 -alkyl, R 2 is H, C 1 -C 4 -alkyl, arylmethyl, C 1 -C 4 -alkoxy or arylmethoxy, R 3 is H, C 1 -C 4 -alkyl or arylmethyl, and R 4, R 5 and R 6 independently are C 1 -C 4 -alkyl or phenyl, (ii) carrying out a coupling reaction (condensation) of the 2-nitropropionic acid derivative of formula (IIc) with an aldehyde of formula Ar-CHO, preferably in the presence of a base substance, wherein Ar is respectively unsubstituted or substituted phenyl, alkyl-aryl, alkoxy-aryl, and obtaining a compound of formula (VIIIa) or (Via) or (iii-1) subjecting the compound of formula (VIIIa) or (VIa) to a conversion reaction to obtain a compound of formula (IXa) by a reaction selected from the group of esterification, dehydration, reduction, hydrogenation, elimination and combinations thereof, or (iii-2) subjecting the compound of formula (VIIIa) to a reduction reaction to obtain optionally forming a salt thereof; wherein the stereogenic center marked with an * is either in - or -configuration at marked center, or it is in racemic form; (iv) if Z is as defined in (i-2), subjecting Z to structural modification, wherein the structural modification comprises steps of • converting a compound of formula (XIIIa) (if Z is other than OH) to compound of formula (XIVa), • activating the carboxylic group in the compound of formula (XIVa) and converting the activated derivative of formula (XIVa) to compound of formula (IXb) by reacting with compound of formula wherein Ar, *, Q and R 10 are as defined above yielding a β-nitro amide compound; • converting a compound of formula (XIIIa) (if Z is other than OH) to compound of formula (XIVa), • activating the carboxylic group in the compound of formula (XIVa) and converting the activated derivative of formula (XIVa) to compound of formula (IXb) by reacting with compound of formula wherein Ar, *, Q and R 10 are as defined above yielding a β-nitro amide compound; (v) if the process optionally proceeds via (iii-1) or (iv), reducing the nitro group in compound of formula (IXa) or the reaction products of (iv) to an amino group to obtain a compound of formula la, optionally forming a salt thereof.