4-Pyrrolidinopyridine → 1-(2-chloro-4-methyl-7,8-dihydro-1,6-naphthyridin-6(5H)-yl)-3-cyclopropylpropane-1,3-dione

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Reaction Steps

Microwave was used to irradiated a suspension of 2-chloro-4-methyl-5,6,7,8-tetrahydro-1,6-naphthyridine hydrochloride (1.00 g, 4.56 mmol), methyl 3-cyclopropyl-3-oxopropanoate (1.298 g, 9.13 mmol), 4-pyrrolidinopyridine (0.068 g, 0.456 mmol) and DIPEA (1.20 mL, 6.85 mmol) in toluene (10 mL) at 150° C. for 45 min. The mixture was cooled to rt and diluted with 1 M HClaq (10 mL) and EtOAc. The products were extracted twice with EtOAc. The combined organic layer was washed with a mixed solution of 1M HClaq/brine (1 mL/2 mL), dried over Na2SO4, filtered, and concentrated to give crude. The residue was purified by flash column chromatography on 12 g of silica gel (eluent: DCM/EtOAc=90:10 to 0:100) to give crude 1-(2-chloro-4-methyl-7,8-dihydro-1,6-naphthyridin-6(5H)-yl)-3-cyclopropylpropane-1,3-dione (0.70 g): MS (ESI+) m/z 293.31 (M+H)+. The obtained material was used without further purification.

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