Synthesis
Step B: Synthesis of methyl 3-amino-4-fluorobenzoate; Methyl 4-fluoro-3-nitrobenzoate (6.57 g, 33 mmol) was dissolved in EtOAc (75 mL) and 10% palladium carbon catalyst (0.66 g) was added. The reaction mixture was transferred to a Fisher-Porter flask and mounted on a hydrogenation unit. The flask was charged with hydrogen (25 psi) and the reaction mixture was stirred overnight at room temperature. Upon completion of the reaction, the catalyst was removed by filtration through a diatomaceous earth pad, followed by concentration of the filtrate to give a yellow oily product which deepened in color on standing and in quantitative yield (5.51 g, 33 mmol). Mass spectrometry (ESI) showed m/z = 170 [M + H]+.
References
[1] Patent: WO2009/76140, 2009, A1. Location in patent: Page/Page column 186
[2] Journal of Organic Chemistry, 1990, vol. 55, # 7, p. 2034 - 2044
[3] Synlett, 2010, # 20, p. 3019 - 3022
[4] Patent: WO2010/126922, 2010, A1. Location in patent: Page/Page column 62
[5] Zhurnal Organicheskoi Khimii, 1972, vol. 8, p. 803,804; engl. Ausg. S. 813, 814
