Acetic Acid → Methyl 8-chloro-1-cyclopropyl-9-methyl-4-oxo-quinolizine-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

Piperidine (7 mL, 70.9 mmol) and acetic acid (5.5 mL, 95 mmol) were added to a solution of 2-(3-methyl-4-chloro-pyridin-2-yl)-2-cyclopropyl-acetaldehyde (4.98 g, 23.75 mmol) in absolute ethanol (200 mL). Dimethyl malonate (16.44 mL, 144 mmol) was added and the reaction mixture was stirred at 100° C. for 5 h (the reaction mixture turned into a red solution). The solvent was evaporated under reduced pressure. The resulting mixture was diluted with ether (100 mL) and washed with water (100 mL) and brine (50 mL). The organic layer was separated and dried over sodium sulfate. The mixture was evaporated to dryness. Dowtherm A (110 mL) was added. This reaction mixture was heated to 240° C. under microwave irradiation and stirred at this temperature for 0.5 h during which the reaction mixture turned into a black solution. The residue was purified by reversed phase flash chromatography using a 5%-100% acetonitrile gradient in water with 1% TFA yielding the cyclized methyl ester (4 g, 51.4%). ESI-MS m/z: 292 (M+H)+; 1H NMR (400 MHz, CDCl3) δ ppm: 9.34 (d, J=7.8 Hz, 1H), 8.42 (s, 1H), 7.13 (d, J=7.8 Hz, 1H), 3.95 (s, 1H), 3.01 (s, 1H), 2.35-2.27 (m, 1H), 1.03-1.08 (m, 2H), 0.72-0.76 (m, 2H); 13C NMR (100 MHz CDCl3) δ ppm 166.6, 155.4, 148.4, 145.5, 142.3, 130.7, 129.0, 117.6, 115.6, 105.4, 52.3, 19.6, 17.0, 9.9 (2CH2).

Provenance & Evidence