To a 25 mL suspension of thionyl chloride of methyl nitrosyl-2-hydroxynicotinate (4.62 g, 23.3 mmol) was added 1 mL of DMF and the reaction mixture was heated to reflux until the reaction was complete as detected by TLC. Subsequently, thionyl chloride was removed by evaporation under reduced pressure and azeotroped twice with toluene to remove residual thionyl chloride. The yellow semi-solid product obtained was cooled in an ice bath and treated with 50 mL of methanol. After stirring for 20 minutes, the mixture was poured into 200 mL of water and extracted with ethyl acetate (2 x 150 mL). The organic phases were combined and washed sequentially with dilute aqueous sodium hydroxide, water and brine, then dried with magnesium sulfate. 5.03 g (99% yield) of methyl 2-chloro-5-nitronicotinate was finally obtained as a yellow oil. Its 1H NMR (400 MHz, deuterated chloroform) data were as follows: δ 4.04 (s, 3H), 8.94 (d, J = 2.78 Hz, 1H), 9.33 (d, J = 2.78 Hz, 1H).
