Oxalyl chloride → Methyl 4-fluoro-3-nitrobenzoate

Participants

Reaction Steps

4-fluoro-3-nitrobenzoic acid (2.5 g, 14 mmol, 1.0 eq) was dissolved in MeOH (68 mL) and heated to reflux. 2.0M oxalyl chloride in CH2Cl2 (14 mL) was added to the refluxing solution slowly and stirred for 2 h at reflux. The reaction was concentrated in vacuo, crystallized at 0° C., and filtered to give 1.7 g (63%) of crude methyl 4-fluoro-3-nitrobenzoate as a white solid. The product was confirmed by LCMS (>98% @ 220 nm and 254 nm) and carried forward without purification. Methyl 4-fluoro-3-nitrobenzoate (1.7 g, 8.4 mmol, 1.0 eq) and 5% palladium on carbon (89 mg, 0.84 mmol, 0.10 eq) were dissolved in EtOH (40 mL) and stirred under H2 atmosphere (1 atm) for 24 h. The mixture was filtered through celite and concentrated in vacuo affording 1.4 g (97%) of crude methyl 3-amino-4-fluorobenzoate as a brown solid. The product was confirmed by LCMS (>98% @ 220 nm and 254 nm) and carried forward without purification. Methyl 3-amino-4-fluorobenzoate (1.4 g, 8.2 mmol, 1.2 eq), 5-bromopyrimidine (1.1 g, 6.8 mmol, 1.0 eq), cesium carbonate (3.1 g, 9.6 mmol, 1.4 eq), Bis(dibenzylideneacetone)palladium (0.50 g, 0.55 mmol, 0.080 eq), and 4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene (0.47 g, 0.82 mmol, 0.12 eq) were dissolved in Dioxane (17 mL) and stirred under argon at 100° C. overnight. The mixture cooled to rt and was filtered through celite and washed with 5% MeOH in CH2Cl2. The filtrate was collected, concentrated in vacuo, and purified by flash chromatography on silica gel afforded 1.5 g (90%) of the title compound as an orange solid: 1H NMR (400 MHz, DMSO-d6) δ 8.73 (s, 1H), 8.63 (s, 1H), 8.50 (s, 2H), 7.84 (dd, J=8.1, 2.1 Hz, 1H), 7.63 (ddd, J=8.5, 4.7, 2.1 Hz, 1H), 7.42 (dd, J=11.2, 8.6 Hz, 1H), 3.83 (s, 3H); ES-MS [M+1]+:248.1.

Provenance & Evidence