Uses
2-Chloro-6-fluorobenzoic Acid is a versatile reactant used in the synthesis of biaryls via decarboxylative Pd-catalyzed cross-coupling with aryl iodides. Also used in the preparation of fluorinated biaryls and heterobiaryls using copper catalyzed decarboxylative cross-coupling of aryl and heteroalyl iodides or bromides with potassium polyfluorobenzoates.
Synthesis
General procedure for the synthesis of 2-chloro-6-fluorobenzoic acid from 2-chloro-6-fluorobenzaldehyde: H3PO4 (454 mg, 3.78 mmol) was added to a solution of 2-chloro-6-fluorobenzamide (1.0 g, 6.31 mmol) in 25 mL of THF and 10 mL of H2O. The reaction mixture was stirred at room temperature for 10 min, followed by the addition of NaClO (1.88 g, 20.81 mmol) and 1.4 mL H2O2 (30% w/w). The reaction was continued to be stirred for 3 h at room temperature. After completion of the reaction, the reaction mixture was extracted with EtOAc. The combined organic layers were washed with 1 M NaOH aqueous solution. The combined aqueous layer was acidified with 1 M HCl aqueous solution to pH ≈ 1 and extracted again with EtOAc. The combined organic layers were washed with brine and dried with anhydrous Na2SO4. After filtration, the solvent was removed in vacuum to afford 1.10 g (99% yield) of 2-chloro-6-fluorobenzoic acid as a colorless solid, which could be used without further purification.1H NMR (400 MHz, CDCl3) δ: 7.44-7.37 (m, 1H), 7.31-7.27 (m, 1H) , 7.10-7.07 (m, 1H).
References
[1] ChemMedChem, 2016, vol. 11, # 23, p. 2607 - 2620
[2] Patent: WO2018/52903, 2018, A1. Location in patent: Page/Page column 47-48
[3] Tetrahedron Letters, 1988, vol. 29, # 16, p. 1967 - 1970
[4] Chemische Berichte, 1936, vol. 69, p. 2253,2255
[5] Tetrahedron Letters, 1988, vol. 29, # 16, p. 1967 - 1970
