3,5-Difluoropyridine → Methyl 4-chloro-1-(3,5-difluoropyridin-4-yl)isoquinoline-7-carboxylate

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Reaction Steps

Under argon gas atmosphere, n-butyllithium (1.6 M THF solution, 0.7 mL) was added dropwise to a mixture of 3,5-difluoropyridine (123 mg) and THF (3 mL) at −78° C., followed by stirring at the same temperature for one hour. Then, zinc chloride (146 mg) was added, and stirred for an additional hour. Methyl 4-chloro-1-{[(trifluoromethyl)sulfonyl]oxy}isoquinoline-7-carboxylate (330 mg) and tetrakis(triphenylphosphine)palladium (206 mg) were added thereto, followed by heating under stirring in an oil bath at 60° C. for 3 hours. The reaction mixture was concentrated under reduced pressure and purified under silica gel column chromatography (hexane/ethyl acetate) to obtain methyl 4-chloro-1-(3,5-difluoropyridin-4-yl)isoquinoline-7-carboxylate (62 mg).

Provenance & Evidence