Phosgene → N-(2,2,3,3-tetrafluorobenzofuran-5-yl)-3-(4-difluoromethoxyphenyl)-4-phenylpyrazoline-1-carboxamide

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Reaction Steps

A solution of 0.75 g (0.0036 mole) of the 5-amino-2,2,3,3-tetrafluorobenzofuran of part A, dissolved in 109 ml of toluene, was added dropwise to a stirred solution of 8.0 ml 20% phosgene in toluene. After complete addition the mixture was heated at reflux for two hours. The mixture was cooled and the solvent removed by evaporation under reduced pressure leaving a residue. This residue was dissolved in 15 ml of diethyl ether and added to a stirred solution of 1.04 g (0.0036 mole) 3-(4-difluoromethoxyphenyl)-4-phenylpyrazoline and three drops of triethylamine in 100 ml of diethyl ether. After complete addition the mixture was heated at reflux for one hour, then cooled to room temperature and stirred for approximately 18 hours. The solvent was removed from the reaction mixture by evaporation under reduced pressure leaving a solid residue. Recrystallization from ethanol provided 0.99 g of N-(2,2,3,3-tetrafluorobenzofuran-5-yl)-3-(4-difluoromethoxyphenyl)-4-phenylpyrazoline-1-carboxamide (mp 155°-159° C.). The nmr spectrum and elemental analysis were consistent with the proposed structure.

Provenance & Evidence