Synthesis
Step A: 3-Fluorotoluene (Compound 1, 18.7 g, 170 mmol) was added to a 500 mL three-necked flask under nitrogen protection and cooled to -78 °C. Subsequently, a THF solution of potassium tert-butoxide (11.0 g, 170 mmol) was slowly added via syringe.After 10 min, a pentane solution of tert-butyllithium (19.0 g, 170 mmol) was slowly added via cannula. The reaction mixture was stirred at -78 °C for 2.5 hours. Upon completion of the reaction, the reaction was quenched with a large amount of crushed fresh dry ice, removed from the -78 °C bath and manually stirred with a metal spatula until the dark brown substance was transformed into a light yellow slurry. After 20 minutes of manual mixing, approximately 500 mL of water was added and the reaction mixture continued to be stirred. Subsequently, the reaction mixture was washed with ether (Et2O) and then acidified with 6N hydrochloric acid to pH less than 3 and extracted again with ether. The organic phases were combined, washed with brine, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated to give compound 2 (10 g, 45% yield).1H NMR (400 MHz, CDCl3) δ 7.90 (t, 1H), 7.04 (d, 1H), 6.97 (d, 1H), 2.39 (s, 3H).
