Bromoform → 5-Bromo-1-(2,6-dichloro-4-trifluoromethylphenyl)-3-cyano-4-trifluoromethylsulfonylpyrazole

Participants

Reaction Conditions

Reaction Steps

A suspension of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethanesulphonylpyrazole (43.8 g) was stirred in a mixture of bromoform (141 ml) and dry acetonitrile (63 ml). Tert-butyl nitrite (29.9 g) was added dropwise during 5 minutes, and the mixture heated at 60-70° C. for 2.75 hours. After cooling to 25° C. a further addition of tert-butyl nitrite (29.9 g) was made, and the heating resumed for 2 hours. Evaporation in vacuo gave a yellow oily solid which was triturated with hexane and filtered off. Two recrystallisations from toluene/hexane gave 5-bromo-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)4-trifluoromethanesulphonylpyrazole as a yellow solid (34.0 g), m.p. 136-137° C.

Provenance & Evidence