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10. General procedure of thiolation of pyrazolones with aryl sulfonyl
chloride in the presence of PPh3: Pyrazolones 5-methyl-2-phenyl-
2,4-dihydro-3H-pyrazol-3-one (1a) (87 mg, 0.5 mmol), 4-
methylbenzenesulfonyl chloride (2a) (114 mg, 0.6 mmol), PPh3
(262 mg, 1.0 mmol) and KI (17 mg, 0.1 mmol) in 1,4-dioxane (1.0
mL) were mixed in a sealed tube. The mixture was stirred at 80 oC
for 12 hours. Then, the solvent was evaporated under reduced
pressure and the residue was purified by silica gel column
chromatography to afford 3-methyl-1-phenyl-4-(p-tolylthio)-1H-
pyrazol-5-ol (3aa) (133 mg, 90%) as a white solid.