Synthesis of 3-benzoyl-4-styryl-2-pyrazolines and their oxidation to the corresponding pyrazoles

The 3-benzoyl-4-styryl-2-pyrazolines 2a-g were prepared from the regioselec tive 1,3-dipolar cycloaddition reactions of (E,E)-cinnamylideneacetophenone s 1a-g and diazomethane. The new compounds 3-(2-benzofuranyl)-4-styryl-2-py razolines (5c,d) were also obtained as by-products in some cases. The oxida tion of the 3-benzoyl-4-styryl-2-pyrazolines 2a-g into 3(5)-benzoyl-4-styry lpyrazoles 3a-g is also reported. Configurational and conformational featur es of all compounds were established by NMR spectroscopy.