0.11 ml of a 1.49M solution of butyllithium in hexane was added, at -78° C. and under an atmosphere of nitrogen, to a solution of 59 mg of 4-chloro-1-(diethylcarbamoyl)-3-(2-ethyl-6-methylphenylsulfonyl)pyrazole (prepared as described in Example 18) in 2 ml of dry tetrahydrofuran, and the resulting mixture was stirred for 30 minutes, after which 15 μl of methyl disulfide were added. The resulting reaction mixture was stirred for 30 minutes, and then mixed with an aqueous solution of ammonium chloride and extracted with diethyl ether. The extract was washed with water, dried over anhydrous sodium sulfate and concentrated by evaporation under reduced pressure. The concentrate was purified by column chromatography through silica gel, eluted with a 10:1 by volume mixture of hexane and ethyl acetate, to afford 28 mg (yield 35%) of the title compound as an oil.
