A slurry of sodium hydride (45 mg of 60% in oil) in dimethyl sulfoxide (2 ml) was stirred at 75° C. for 45 minutes, cooled to room temperature, then (2-(trimethylsilyl)-ethoxymethyl)triphenylphosphonium chloride (480 mg) was added in one portion to produce a red solution. After 10 minutes, a solution of 5-(4-chloro-phenyl)-1-(2-chloro-phenyl)-4-formyl-1H-pyrazole-3-carboxylic acid ethyl ester (218 mg) in dimethylsulfoxide (1 ml) was added dropwise and the resulting solution was stirred for 1 hour. Saturated aqueous ammonium chloride was added and the reaction mixture was partitioned between diethyl ether and water. The organic phase was dried (Na2SO4) and concentrated in vacuo to afford a purple oil. Silica gel chromatography (30% ethyl acetate/hexanes) afforded the title compound (I-3a) as a golden oil, 210 mg.
