Ethyl chloroformate → Ethyl 3-(2-fluorophenyl)prop-2-ynoate

Participants

Reaction Steps

To a −78° C. solution of 1-ethynyl-2-fluorobenzene (0.94 g, 7.83 mmol) in anhyd. THF (25 mL) was added dropwise a solution of n-BuLi (1.6M in hexanes, 5.14 mL, 8.22 mmol). The solution was stirred for 10 min, then ethyl chloroformate (2.24 mL, 23.5 mmol) was added and the reaction mixture was allowed to warm to room temperature. The resulting mixture was poured onto ice water (200 mL) and extracted with Et2O. The organic layer was dried (MgSO4) and concentrated under reduced pressure to give ethyl 3-(2-fluorophenyl)prop-2-ynoate (1.68 g) as a yellow oil. The crude product was dissolved in MeOH (10 mL) and was added to a 5° C. mixture of a 1N NaOH solution (12.5 mL) and MeOH (30 mL). The reaction mixture was allowed to warm to room temperature, stirred for 1 h, treated with a 1N HCl solution (15 mL) and a saturated NaCl solution (20 mL). The resulting mixture was extracted with EtOAc, dried (MgSO4) and concentrated under reduced pressure to give 3-(2-fluorophenyl)prop-2-ynoic acid (1.22 g, 95% for two steps) as a tan solid: TLC (100% EtOAc) Rf 0.18; 1H NMR (acetone-d6) δ 7.30 (m, 2H), 7.60 (m, 2H), 12.0 (s, 1H).

Provenance & Evidence