Compound of formula ** Formula ** in which R 1 represents phenyl, the phenyl being substituted with 1 to 3 substituents, the substituents being selected independently from each other from the group consisting of halogen, hydroxyl, cyano, nitro, trifluoromethyl, trifluoromethoxy, trifluoromethylthio, (C1-C4) alkyl and (C1-C4) alkoxy, in which (C1-C4) alkyl and (C1-C4) alkoxy, in turn, can be mono to trisubstituted, in the same or different manner, with radicals selected from the series comprising halogen, cyano, hydroxyl, (C1-C4) alkoxy, amino, mono (C1-C4) amino, dialkyl (C1-C4) amino, cycloalkyl (C3-C7) and 4-heterocyclyl to 7 members, the cycloalkyl and heterocyclyl radicals mentioned last being, in turn, in each case, even trisubstituted, in the same or different manner, with halogen, cyano, (C1-C4) alkyl, trifluoromethyl, hydroxyl, alkoxy (C1-C4), trifluoromethoxy, oxo, amino, mono (C1-C4) alkyl and amino quil (C1-C4) amino, R2 represents phenyl, the phenyl being substituted with 1 to 3 substituents, the substituents being selected independently from each other from the group consisting of halogen, hydroxyl, cyano, nitro, trifluoromethyl, trifluoromethoxy, trifluoromethylthio, alkyl (C1-C4) and (C1-C4) alkoxy, in which (C1-C4) alkyl and (C1-C4) alkoxy, in turn, can be mono to trisubstituted, in the same or different manner, with selected radicals of the halogen, cyano, hydroxyl, (C1-C4) alkoxy, amino, mono (C1-C4) amino, dialkyl (C1-C4) amino, cycloalkyl (C3-C7) and 4- to 7-membered heterocyclyl series, being able to be the cycloalkyl and heterocyclyl radicals mentioned last, in turn, in each case even trisubstituted, in the same or different manner, with halogen, cyano, (C1-C4) alkyl, trifluoromethyl, hydroxyl, (C1-C4) alkoxy, trifluoromethoxy , oxo, amino, mono (C1-C4) alkyl and dialkyl (C1-C4) amino, and R3 represents a radical nitrogen-linked heterocyclyl, the heterocyclyl radical being substituted with 1 to 3 substituents, the substituents being selected in
