Synthesis and Anticancer Activity of Some New Fused Pyrazoles and Their Glycoside Derivatives

4‐(4‐Chlorobenzylidene)‐2,5‐diphenyl‐2,3‐dihydro‐3 H ‐pyrazol‐3‐one 3a and 4‐(3,4‐dimethoxybenzylidene)‐5‐phenyl‐2,3‐dihydro‐3 H ‐pyrazol‐3‐one 3b were prepared and were reacted with phenylhydrazine, thiosemicarbazide, hydroxylamine hydrochloride, ethyl acetoacetate, diethylmalonate, malononitrile, ethyl cyanoacetate, and thiourea yielding fused pyrazole derivatives. Some of the new compounds were reacted with cyclic and acyclic sugars to produce new S ‐, O ‐, and N ‐glycoside derivatives. The antitumor activity against the human breast cancer cells (MCF‐7) was assessed. Four of the new compounds showed IC 50 values less than those of the positive control, indicating that these four compounds are better anticancer agents than doxorubicin.