(4-Chloro-2-fluoro-5-propan-2-yloxyphenyl)hydrazine → 2-(2-Fluoro-4-chloro-5-isopropoxyphenyl)-4-methyl-5-trifluoromethylpyridazin-3-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 5.3 g (53.3 mmol) of sodium acetate mixed with about 100 ml of water was added under ice cooling 6.6 g (24.3 mmol) of 1,1-dibromo-3,3,3-trifluoroacetone, and the mixture was stirred at 70° C. for 20 minutes. The reaction mixture was cooled to room temperature, to which a solution of 5.8 g (21.5 mmol) of 2-fluoro-4-chloro-5-isopropoxyphenylhydrazine dissolved in about 20 ml of diethyl ether was added, and the mixture was stirred at room temperature for 1 hour. The ether layer was separated and then concentrated. About 60 ml of tetrahydrofuran (hereinafter referred to as THF) was added to the residue, to which 8.3 g (23.0 mmol) of (carbethoxyethylidene)triphenylphosphorane was added, and the mixture was heated under reflux for 2 hours. The THF was distilled out under reduced pressure, and the residue was subjected to silica gel column chromatography, which afforded 3.8 g (10.5 mmol) of 2-[2-fluoro-4-chloro-5-isopropoxyphenyl]-4-methyl-5-trifluoromethylpyridazin-3-one.

Provenance & Evidence