R¹ is α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4-or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R², R⁵, R⁶ and R⁷ are C₁-C₁₈-alkyl, or C₂-C₁₈-alkyl, C₂-C₁₈-alkenyl, C₆-C₁₂-aryl or C₅-C₁₂-cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R² is furthermore C₁-C₁₈-alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R¹—(C═Y)—,

Y is O, S, NR³, N—OR³ or N—NR³R⁴,

Z is O, S, NR³, N—OR³, N—NR³R⁴ or a free pair of electrons,

R³ is hydrogen, C₁- to C₄-alkyl, SO₃H, phenyl or acetyl,

R⁴ is hydrogen, C₁- to C₄-alkyl, COOR³, or C₆-C₁₂-aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N⁺R⁶R⁷R⁸, —O(CO)R⁵, —O(CO)OR⁵, —O(SO)Cl, —O(SO₂)OR⁵, —O(SO₂)R⁵ or —O(CO)Cl,

R⁵ is furthermore C₁-C₁₈-alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R⁸ is C₁-C₁₈-alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C₂-C₁₈-alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups.