Method for preparing a compound of formula where R1, R2, and R3 independently represent a hydrogen atom; a halogen atom; a hydroxy group, an alkyl group; a hydroxy alkyl group; a haloalkyl group; an alkoxy group having 1 to 4 carbon atoms; an amino group; an alkylamino group or an acylamido group having 1 to 10 carbon atoms; A represents a hydrogen atom; a C1-C5 alkyl group; or an alkoxycarbonyl group; B represents a nitrile group;a carboxylic acid group, a carboxylic acid ester group or a carboxylic acid amide group; the method comprising steps of- (a) forming a first reaction mixture comprising - a catalyst complex comprising Cu and a ligand, wherein the ligand is selected from mono-, bi- or polydentate amine ligands; - an organic sulphonate counterion; - a reactive solvent selected from (meth)acrylonitrile or alkyl (meth)acrylate; and - an aryl sulfonyl halide reactant; (b) allowing a reaction to proceed in the first reaction mixture at an elevated temperature, whereby an intermediate product is obtained; (c) separating the unreacted reactive solvent from the first reaction mixture, and dissolving the intermediate product to a low polarity solvent to form a second reaction mixture; (d) adding a base to the second reaction mixture, wherein the intermediate product undergoes a base-catalyzed elimination of the halogen atom from the intermediate product to form the compound according to Formula, preferably under cooling; and (e) separating the compound according to Formula from the second reaction mixture. R1, R2, and R3 independently represent a hydrogen atom; a halogen atom; a hydroxy group, an alkyl group; a hydroxy alkyl group; a haloalkyl group; an alkoxy group having 1 to 4 carbon atoms; an amino group; an alkylamino group or an acylamido group having 1 to 10 carbon atoms; A represents a hydrogen atom; a C1-C5 alkyl group; or an alkoxycarbonyl group; B represents a nitrile group;a carboxylic acid group, a carboxylic acid ester group or a carboxylic acid amide group; the method comprising steps of- (a) forming a first reaction mixture comprising - a catalyst complex comprising Cu and a ligand, wherein the ligand is selected from mono-, bi- or polydentate amine ligands; - an organic sulphonate counterion; - a reactive solvent selected from (meth)acrylonitrile or alkyl (meth)acrylate; and - an aryl sulfonyl halide reactant; (b) allowing a reaction to proceed in the first reaction mixture at an elevated temperature, whereby an intermediate product is obtained; (c) separating the unreacted reactive solvent from the first reaction mixture, and dissolving the intermediate product to a low polarity solvent to form a second reaction mixture; (d) adding a base to the second reaction mixture, wherein the intermediate product undergoes a base-catalyzed elimination of the halogen atom from the intermediate product to form the compound according to Formula, preferably under cooling; and (e) separating the compound according to Formula from the second reaction mixture. (a) forming a first reaction mixture comprising - a catalyst complex comprising Cu and a ligand, wherein the ligand is selected from mono-, bi- or polydentate amine ligands; - an organic sulphonate counterion; - a reactive solvent selected from (meth)acrylonitrile or alkyl (meth)acrylate; and - an aryl sulfonyl halide reactant; - a catalyst complex comprising Cu and a ligand, wherein the ligand is selected from mono-, bi- or polydentate amine ligands; - an organic sulphonate counterion; - a reactive solvent selected from (meth)acrylonitrile or alkyl (meth)acrylate; and - an aryl sulfonyl halide reactant; (b) allowing a reaction to proceed in the first reaction mixture at an elevated temperature, whereby an intermediate product is obtained; (c) separating the unreacted reactive solvent from the first reaction mixture, and dissolving the intermediate product to a low polarity solvent to form a second reaction mixture; (d) adding a base to the second reaction mixture, wherein the intermediate product undergoes a base-catalyzed elimination of the halogen atom from the intermediate product to form the compound according to Formula, preferably under cooling; and (e) separating the compound according to Formula from the second reaction mixture.