Water → 3-(3-Fluoro-4-pyridinylamino)-1H-indole hydrochloride

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Reaction Steps

A solution of 3-aminoindole (7 g) and 4-chloro-3-fluoropyridine hydrochloride (13 g) in 200 mL of 1-methyl-2-pyrrolidinone was stirred at 75-80° C. for two hours, after which additional 4-chloro-3-fluoropyridine hydrochloride (5 g) was added. After stirring a total of three hours the mixture was cooled, stirred with water, basified with sodium carbonate and extracted with ethyl acetate. The dried (anhydrous magnesium sulfate) organic layer was filtered and concentrated to 20 g of a dark oil. Elution through silica gel first with dichloromethane and then with 50% ethyl acetate in dichloromethane via flash column chromatography yielded 17 g of a dark oil. This oil was eluted through silica with ether via flash column chromatography to yield 10.6 g of a dark oil. This oil was eluted through silica with 20% ethyl acetate in dichloromethane via HPLC to yield 8 g of a dark oil. A six gram portion was converted to the hydrochloride salt in methanol/ether to yield 3.5 g of a solid, m.p. >250° C. Recrystallization from 30% methanol in ether yielded 2.7 g of crystals, m.p. 256-258° C. (dec.).

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