Patent ID: 7501527

Claim:
A process for preparing fluoromethyl-substituted heterocycles of formula (I) in which R 1 is, fluorine or chlorine, R 2 is hydrogen, R 3 is C 1 -C 6 -alkyl, A is a pyrazole that is substituted by R 4 in the 1-position, and R 4 is C 1 -C 4 -alkyl, C 3 -C 6 -cycloalkyl, C 1 -C 4 -alkylthio-C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, or phenyl, comprising converting a chloromethyl-substituted heterocycle of formula (II) in which R 1 is chlorine, and R 2 , R 3 , and A are each as defined for formula (I), to a fluoromethyl-substituted heterocycle of formula (I) in the presence of a fluorinating agent selected from the group consisting of 3 HF/N(Et) 3 (Franz reagent), 3 HF/N(n-Bu) 3 , and HF/pyridine (Olah's reagent) and optionally in the presence of a diluent.