To a mixture of 1-(3-tert-butyldiphenylsilyloxymethyl-2,4-dichlorophenyl)-2-cyanopyrrole (900 mg) and silicic acid (100 mg) in carbon tetrachloride (15 ml) was added a solution of tert-butyl hypochlorite (222 mg) in carbon tetrachloride (10 ml) in water bath, and the mixture was stirred for 30 minutes at the same temperature. The reaction mixture was filtered, and the filtrate was evaporated in vacuo. The residue was purified by silica gel column chromatography eluting with a mixture of n-hexane and ethyl acetate (15:1, V/V) to give 1-(3-tert-butyldiphenylsilyloxymethyl-2,4-dichlorophenyl)-4-chloro-2-cyanopyrrole (290 mg) as an oil.
