Phosphorus oxychloride → Ethyl 4-chloro-3-cyanopyrrolo[1,2-b]pyridazine-6-carboxylate

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Reaction Conditions

Reaction Steps

To a round bottom flask was added POCl3 (200 mL) and ethyl 3-cyano-4-hydroxypyrrolo[1,2-b]pyridazine-6-carboxylate (20 g, 80 mmol). The reaction was heated under nitrogen at 75° C. for 2 hours. The reaction was cooled to room temperature and POCl3 was removed under vacuum. The residue was poured onto ice-water. The aqueous solution was extracted with CH2Cl2. The organic layer was washed with saturated sodium carbonate solution, dried and concentrated. The resulting residue was purified by flash silica gel column chromatography to yield 10 g (48%) of the title compound as a yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm: 8.33 (1H, d, J=1.3 Hz), 8.11 (1H, s), 7.41 (1H, d, J=1.6 Hz), 4.41 (2H, q, J=6.8 Hz), 1.41 (3H, t, J=6.8 Hz).

Provenance & Evidence