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.