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0 °C

Nitrosomethyl urea (8 g, 78.16 mmol), taken in diethyl ether (30 ml) was cooled to 0° C. and 25% aqueous KOH solution was added slowly under cooling. The ether layer was collected, dried over KOH and added dropwise to a stirring solution of 2,4-Dichloronicotinic acid (3 g, 15.62 mmol) in methanol (5 mL) at 0° C. The reaction mixture was allowed to come to room temperature within 1 hour. The organic solvent was removed under reduced pressure and the crude residue was purified by column chromatography (5-10% EtOAc in hexane) to obtain the pure methyl 2,4-dichloronicotinate (3.00 g, 99%) as colorless oil. 1H NMR (400 MHz, CDCl3): δ 8.34 (d, J=5.3 Hz, 1H), 7.33 (d, J=5.4 Hz, 1H), 3.99 (s, 3H).

1. temperatureunder cooling
2. customThe ether layer was collected
3. dry with materialdried over KOH
4. customThe organic solvent was removed under reduced pressure
5. customthe crude residue was purified by column chromatography (5-10% EtOAc in hexane)