Dimethylformamide → 3-(3-fluoro-5chloro-2-pyridyl)-5-difluoromethoxy-1-methyl-[1H]-pyrazole

Participants

Reaction Conditions

Reaction Steps

46.0 g of 3-(3-fluoro-5-chloro-2-pyridyl)-5-hydroxy-1-methyl-[1H]-pyrazole (Example H14) and 84 g of potassium carbonate are initially introduced into 250 ml of dry dimethylformamide and the mixture is heated up to 85° C. Freon 22 (chlorodifluoromethane) is then passed in over a period of 2 hours, with thorough stirring. TLC analysis of a worked-up sample (silica gel 60 F254; n-hexane/ethyl acetate/glacial acetic acid 20/20/1, UV) shows that no further starting material is present. The reaction mixture is partitioned between water and diethyl ether (foaming on addition of water). After extraction by shaking and separation of the phases, the ether phase is washed twice with water and once with brine. After the organic phase has been dried over sodium sulfate and filtered, the filtrate is concentrated in vacuo and the residue is purified by means of flash chromatography (silica gel; eluting agent: n-hexane/ethyl acetate 2/1 (v/v)). 22.0 g of the desired title compound are obtained as a pale yellow solid.

Provenance & Evidence