Preparation of 3-amino-2-(het)aroyl-acrylic acid derivatives

A process for the preparation of a 3-amino-2-(het)aroylacrylic acid derivative of the formula ##STR41## in which Y represents a nitrile, an ester group --COOR.sub.1, or an acetyl group,

• R.sup.1 denotes C.sub.1 -C.sub.4 -alkyl and
• R denotes alkyl having 1 to 6 carbon atoms, 2-fluoroethyl, 2-chloroethyl, 2-hydroxyethyl, 1-(hydroxymethyl)-ethyl, cyclopropyl, methoxy, 4-fluorophenyl, 2,4-difluorophenyl, dimethylamino, formyl-methylamino or isopropylideneamino,
• A represents nitrogen or C-R.sub.2, where
• R.sub.2 denotes hydrogen, methyl, halogen, nitro, methoxy or cyano,
• X.sub.1 and X.sub.2 are identical or different and denote halogen, and
• X.sub.3 denotes hydrogen, halogen or nitro and
• X.sub.4 denotes halogen, nitro, methoxy or methylthio, which comprises reacting a 3-dialkylamino-2-(het)aroylacrylic acid derivative of the formula ##STR42## in which R.sub.3 and R.sub.4 are the same or different and represent an alkyl group having 1 to 4 carbon atoms or, together with the nitrogen atom to which they are bonded, form a 5- or 6-membered ring which additionally can contain the atoms or groups --O--, --S-- or --SO.sub.2 --,
• with a primary amine of the formula R--NH.sub.2 in the presence of at least one equivalent of an acid HX in a solvent or in excess acid.