5-Chloro-3-fluoro-2-phenylsulfinylpyridine → 5-Chloro-3-fluoro-2-(4-chloro-2-fluoro-5-methoxyphenyl)pyridine

A Grignard solution of 12.9 g (0.049 mol) of 4-chloro-2-fluoro-5-methoxyphenylmagnesium bromide in 60 ml of THF was added with stirring at 23-30° C. to a solution of 10 g (0.0392 mol) of 5-chloro-3-fluoro-2-phenylsulfinylpyridine in 150 ml of THF over a period of 10 min, and the mixture was stirred at 23° C. for another 4 h. The reaction mixture was concentrated under reduced pressure, taken up in methylene chloride and extracted in succession with 1 N hydrochloric acid, 1 N of aqueous sodium hydroxide solution and with water, and dried. The solution was filtered with suction through silica gel, concentrated, stirred with pentane, filtered off with suction and dried, affording 5.7 g (50.1% of theory) of the title compound of mp. 120-122° C.