Tandem Addition/Cyclization/Halogenation Reaction of Difluoromethylated N -Acylhydrazones with Allyltrimethylsilanes.

As novel difluoromethyl building blocks, difluoromethylated N -acylhydrazones react with allyltrimethylsilanes and the halogen source via a tandem addition/cyclization/halogenation strategy, which produces various difluoromethylpyrazoline compounds in good yields. The method features mild reaction conditions, broad substrate scopes, and a transition metal-free process with easy operation. It also proves that difluoromethylated N -acylhydrazones are useful difluoromethyl building blocks for the construction of difluoromethylated nitrogen heterocycles.