Sodium Bicarbonate → 5-Amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-propanoylpyrazole

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Reaction Steps

p-Toluenesulphonic acid monohydrate (2.92 g) was added to a stirred solution of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-(prop-1-yn-1-yl)pyrazole (WO-A-97/07102; 2.1 g) in acetonitrile (40 ml) and the mixture stirred at room temperature for 1 hour. Further p-toluenesulphonic acid monohydrate (1.0) was added and this mixture stirred at room temperature for 16 hours. Further acetonitrile (20 ml) and yet more p-toluenesulphonic acid monohydrate (1.0 g) were added and stirring continued for 1 hour, then the reaction mixture was poured into saturated aqueous sodium bicarbonate solution (500 ml) and extracted with ether (2×100 ml). The combined organic extracts were washed with brine (100 ml), dried (Na2SO4) and evaporated under reduced pressure, then the residue purified by column chromatography on silica gel (70 g), using dichloromethane as eluant, to yield the title compound as a pale brown solid, m.p. 167-169° C. δ (CDCl3): 1.26 (t,3H), 3.03 (q,2H), 5.83 (br.s,2H), 7.80 (s,2H). MS (thermospray): M/Z [M+H] 377.2; C14H9Cl2F3N4O+H requires 377.0.

Provenance & Evidence