A solution of t-butyl nitrite (1.14 ml) in CHCl3 (3 ml) was added dropwise to a solution of 5-[4-(benzyloxy)phenyl]-1-(4-methoxyphenyl)-3-amino-1H-pyrazole (1.5 g) and dimethyldisulfide (1.15 ml) in CHCl3 (10 ml). After all of t-butyl nitrite solution was added, the temperature of reaction mixture began to rise and reached to reflux. After the reflux ceased, the mixture was stirred at ambient temperature for 1 hour. The mixture was concentrated in vacuo and the residue was purified by silica gel column chromatography eluted with AcOEt/n-hexane=25% to give 5-[4-(benzyloxy)phenyl]-1-(4-methoxyphenyl)-3-(methylthio)-1-H-pyrazole (635.2 mg) as an oil.
