Patent ID: 7335780

Claim:
A method for preparing a 3-halo-4,5-dihydro-1H-pyrazole compound of Formula I wherein L is an optionally substituted carbon moiety; each R is independently selected from optionally substituted carbon moieties; k is an integer from 0 to 4; and X 1 is halogen; comprising: contacting a 4,5-dihydro-1H-pyrazole compound of Formula II wherein X 2 is OS(O) m R 1 , OP(O) p (OR 2 ) 2 or a halogen other than X 1 ; m is 1 or 2; p is 0 or 1; R 1 is selected from alkyl and haloalkyl; and phenyl optionally substituted with from 1 to 3 substituents selected from alkyl and halogen; and each R 2 is independently selected from alkyl and haloalkyl; and phenyl optionally substituted with from 1 to 3 substituents selected from alkyl and halogen; with a compound of the formula HX 1 in the presence of a suitable solvent.