Synthesis
Methyl 2-methyl-4-nitrobenzoate (Intermediate 5) (3.25 g, 16.6 mmol) was used as raw material, which was dissolved in ethanol, 10% Pd/C (catalytic amount) and ammonium formate (10.5 g, 0.17 mmol) were added. The reaction mixture was stirred at 40 °C for 2 hours. After completion of the reaction, the mixture was filtered through diatomaceous earth and the diatomaceous earth was washed with ether. The filtrate and washings were combined and the solvent was evaporated under reduced pressure to give the crude product. The crude product was dissolved in ether and washed with water to remove water-soluble impurities. The organic phase was separated, dried with anhydrous Na2SO4, filtered and evaporated the solvent under reduced pressure to give methyl 2-methyl-4-aminobenzoate as a brown oil (2.8 g, quantitative yield). The structure of the product was confirmed by 1H NMR (300 MHz, CDCl3): δ 7.74 (d, 1H, J = 9.20Hz), 6.41 (m, 2H), 3.75 (s, 3H), 2.47 (s, 3H).
References
[1] Patent: WO2009/47240, 2009, A1. Location in patent: Page/Page column 29
[2] Bioorganic and Medicinal Chemistry Letters, 2008, vol. 18, # 3, p. 942 - 945
[3] Bioorganic and Medicinal Chemistry Letters, 2008, vol. 18, # 3, p. 946 - 949
[4] Bulletin de la Societe Scientifique de Bretagne, 1956, vol. 31, p. Sonderheft S.9,41
[5] Patent: WO2006/7542, 2006, A1. Location in patent: Page/Page column 24
