5-(4-Chloro-5-difluoromethoxy-1-methyl-1H-pyrazol-3-yl)-2,4-dichlorobenzoic acid → N-[2-(1,3-dioxolan-2-yl)ethyl]-N-methyl-5-(4-chloro-5-difluoromethoxy-1-methyl-1H-pyrazol-3-yl)-2,4-dichlorobenzamide

After a solution of 1 g (2.7 mmol) of 5-(4-chloro-5-difluoromethoxy-1-methyl-1H-pyrazol-3-yl)-2,4-dichlorobenzoic acid and 0.66 g (4.1 mmol) of 1,1-carbonyldiimidazole had been stirred for 1 hour in 20 ml of tetrahydrofuran, 0.55 g (4.1 mmol) of N-[2-(1,3-dioxolan-2-yl)-ethyl]-N-methylamine were added. The mixture was subsequently stirred for a further 16 hours at approximately 20° C. The reaction mixture was then concentrated. The crude product was purified by chromatography on silica gel (eluent: hexane/ethyl acetate=1:1). Yield: 0.4 g.