N([O-])=O.[Na+].N[C:6]1[CH:15]=[C:14]([Cl:16])[CH:13]=[CH:12][C:7]=1[C:8]([O:10][CH3:11])=[O:9].S(=O)(=O)(O)O.[C:22]([OH:26])(=[O:25])[CH:23]=[CH2:24]>O.C/C(/[O-])=C/C(C)=O.C/C(/[O-])=C/C(C)=O.[Pd+2]>[Cl:16][C:14]1[CH:13]=[CH:12][C:7]([C:8]([O:10][CH3:11])=[O:9])=[C:6]([CH:24]=[CH:23][C:22]([OH:26])=[O:25])[CH:15]=1At 2° C., a solution of 5.96 g of sodium nitrite in 11.3 ml of water is added to a mixture of 14 g of methyl 2-amino-4-chlorobenzoate, 59 ml of water and 14.3 ml of concentrated sulfuric acid. The reaction mixture is subsequently stirred for 20 minutes and then added a little at a time to 6.9 g of acrylic acid, 57 mg of palladium acetylacetonate being added after the first portion. After 4 hours at 40° C., the precipitated solid is filtered off, giving, after washing and drying, 18.5 g of methyl 4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)-benzoate.
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