Synthesis
Sulfoxide chloride (SOCl2, 0.6 mL) was slowly added dropwise to anhydrous methanol (MeOH, 10 mL) at 0 °C. The reaction mixture was stirred continuously for 0.5 h at this temperature. Subsequently, 3-hydroxy-2-nitrobenzoic acid (0.6 g, 3.2 mmol) was added to the mixture. The reaction system was heated to reflux and maintained for 4 hours. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent ratio of petroleum ether: ethyl acetate = 1:1) to confirm the completion of the reaction. After completion of the reaction, the mixture was concentrated under vacuum to afford the target product methyl 2-nitro-3-hydroxybenzoate (0.63 g, 100% yield) as a brown solid.
References
[1] Patent: WO2007/125405, 2007, A2. Location in patent: Page/Page column 24; 72-73
[2] Nippon Kagaku Zasshi, 1953, vol. 74, p. 251
[3] Chem.Abstr., 1954, p. 3959
[4] Patent: US2002/52397, 2002, A1
[5] Patent: US5756510, 1998, A
