PREPARATION OF TRIFLUOROMETHYL-PYRAZOLES AND TRIFLUOROMETHYL-PYRAZOLINES BY THE REACTION OF 2,2,2-TRIFLUORODIAZOETHANE WITH CARBON-CARBON MULTIPLE BONDS

1,3-Dipolar addition of 2,2,2-trifluorodiazoethane to a series of alkenes and alkynes gives good yields of the corresponding pyrazolines and pyrazoles. Chloromethyl and bromomethyl substituents activate the multiple bond more than does a phenyl substituent. A combination of electronics effects and steric hindrance accounts for the reactivity of 3,3,3-trichloropropene, methyl methacrylate, and allyl formate. © 1979.