A solution of 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-N-methoxy-4-methylsulfinyl-1H-pyrazole-3-carboximidamide (0.5 g) in anhydrous THF was stirred at 0-5° C. and potassium tert-butoxide (0.13 g) and lodomethane (0.081 ml) added. After three hours further potassium tert-butoxide (0.068 g) and iodomethane (0.08 ml) were added at 0-5° C. The mixture was stirred at this temperature for 16 hours, evaporated and the residue purified by chromatography on silica gel eluting with 3:1 dichloromethane/ethyl acetate to give 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-N-methoxy-N′-methyl-4-methylsulfinyl-1H-pyrazole-3-carboximidamide (0.13 g), m.p. 139-142° C. Compound 50.
