1-(4-Chlorophenyl)-4,4,4-trifluorobutane-1,3-dione → 4-(5-(4-Chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide

Participants

Reaction Steps

4-Sulphonamidophenylhydrazine hydrochloride (982 mg, 4.4 mmol 1,1-equivalent) was added to a stirred solution of 4,4,4-trifluoro-1-[4-(chloro)phenyl]-butane-1,3-dione from Step 1 (1.00 g, 4.0 mmol) in ethanol 150 mL). The reaction was heated to reflux and stirred for 20 hours. (HPLC area percent showed a 96:3 ratio of 4-[4-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide to its regioisomer (4-[3-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide. After cooling to room temperature, the reaction mixture was concentrated in vacuo. The residue was taken up in ethyl acetate, washed with water and with brine, dried over MgSO4, filtered, and concentrated in vacuo to give a light brown solid which was recrystallized from ethyl acetate and iso-octane to give the pyrazole (1.28 g, 80%, mp 143-145° C.). HPLC showed that the purified material was a 99.5:0.5 mixture of 4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide to its regioisomer. 1H NMR (CDCl3/CD3OD 10/1) d 5.2 (s, 2H), 6.8 (s, 1H), 7.16 (d, j=8.5 Hz, 2H), 7.35 (d, j=8.5 Hz, 2H), 7.44 (d, j=8.66, 2H), 7.91 (d, j=8.66, 2H.); 13C NMR (CDCl3/CD3OD 10/1) d 106.42 (d, j=0.03 Hz), 121.0 (q, j=276 Hz), 125.5, 126.9, 127.3, 129.2, 130.1, 135.7, 141.5, 143.0, 143.9 (q, j=37 Hz), 144.0; 19F NMR (CDCl3/CD3OD 10/1) d −62.9. EI GC-MS M+=401.

Provenance & Evidence