Dichloromethane → 3-Cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoroacetylpyrazole

Participants

Reaction Conditions

Reaction Steps

t-Butyl nitrite (12.45 ml) was added dropwise to a stirred solution of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoroacetylpyrazole (JP-A-8-311036; 30 g) in tetrahydrofuran (250 ml) and the mixture stirred at 55° C. for 16 hours. Further quantities of t-butyl nitrite added/subsequent periods of stirring at 55° C. were as follows: 9 ml/7 hours, 6 ml/16 hours, 9 ml/6 hours, 4.75 ml/16 hours, 6 ml/6 hours and 3.5 ml/22 hours. The reaction mixture was allowed to cool and evaporated under reduced pressure, then the residue combined with those obtained from three identical preparations. Purification by column chromatography on silica gel (1 Kg), using hexane:dichloromethane (6:4) and then dichloromethane as eluants, gave a yellow oil which, on trituration with hexane (3×50 ml) followed by dichloromethane (100 ml), provided the title compound as a white solid, m.p. 124-125° C. δ (CDCl3): 7.83 (s,2H), 8.30 (s,1H). MS (thermospray): M/Z [M+H] 401.7; C13H3Cl2F6N3O+H requires 401.96.

Provenance & Evidence