Synthesis
Method B: Synthesis of 2-fluoro-6-(2H-1,2,3-triazol-2-yl)benzoic acid. In a 2L three-necked round-bottomed flask equipped with an overhead mechanical stirrer, a thermocouple probe, a heating jacket, a reflux condenser, and a nitrogen inlet, 2-fluoro-6-iodobenzoic acid (127.6 g, 480 mmol), copper iodide (4.57 g, 24 mmol), and Cs2CO3 (312.6 g, 959 mmol) were added in sequence. To the solid mixture was added dioxane (640 mL) followed by water (2.6 mL, 144 mmol), 1H-1,2,3-triazole (55.6 mL, 959 mmol) and trans-1,2-dimethylcyclohexane-1,2-diamine (15.1 mL, 96 mmol). The reaction mixture was gradually warmed up to 60°C for 30 minutes, then warmed up to 83°C for 30 minutes and finally warmed up to 100°C for 3 hours of reaction. After completion of the reaction, the mixture was cooled and 1 L of methyl tert-butyl ether (MTBE) and 1 L of water were added. After vigorous stirring, the organic and aqueous layers were separated. The aqueous layer was acidified with concentrated hydrochloric acid (148 mL) to pH 1.72. The acidified aqueous layer was extracted twice with ethyl acetate (EtOAc). The organic layers were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated to give a dark colored oil. The oil was dissolved in ethyl acetate (450 mL), stirred overnight and filtered to remove the precipitate. Concentration of the mother liquor gave a brown solid product (106.21 g, 75 wt%, quantitative HPLC showed 79.7 g, 80% yield).1H NMR (400 MHz, DMSO-d6) δ: 8.22-8.13 (broad peak, 2H), 7.84-7.80 (multiple peaks, 1H), 7.74-7.65 (multiple peaks, 1H), 7.50- 7.41 (multiple peaks, 1H).
