Water → Dimethyl 7-chloroquinoline-2,3-dicarboxylate

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Reaction Steps

A stirred mixture of dimethyl 4,7-dichloroquinoline-2,3-dicarboxylate (5.00 g, 15.9 mM), sodium formate (1.63 g, 23.9 mM) and tetrakis(triphenylphosphine)palladium(O) (0.92 g, 0.80 mM) in anhydrous dimethylformamide (75 mL) under a nitrogen atmosphere was heated at 90°-95° C. for 7 hr. No reaction occurred so the reaction mixture was degassed and an additional quantity of tetrakis(triphenylphosphine)palladium(O) (0.92 g, 0.80 mM) was added and the reaction mixture again heated at 90°-95° C. for 6 hr. The cooled reaction mixture was poured into water and the resulting mixture extracted with ethyl acetate. The combined extracts were dried (MgSO4), filtered and concentrated to leave an gummy solid (6.0 g). Trituration of this residue with ethyl acetate and subsequent filtration separated a crystalline solid which was shown to be dimethyl 7-chloro-4-hydroxyquinoline-2,3-dicarboxylate. The filtrate was concentrated and the residue was flash chromatographed over silica gel (eluant: hexane/ethyl acetate, 3/2) to provide the title diester (1.13 g, 25.4%) as a light yellow crystalline solid; MS(CI): 280 (M+H). 300-MHz 1H NMR (DMSO d6), 9.15 (s, 1H), 8.33 (d, 1H, J=9 Hz), 8.25 (d, 1H, J=2 Hz), 7.86 (dd, 1H, J=9 Hz, 2 Hz), 3.93 (s, 3H), 3.92 (s, 3H).

Provenance & Evidence