Synthesis
GENERAL METHOD: To a solution of 2,3-dichloropyridine (1.00 g, 6.76 mmol) in dimethyl sulfoxide (DMSO, 33.8 mL) was added cesium fluoride (CsF, 2.053 g, 13.51 mmol) at room temperature. The reaction mixture was stirred in air at 110 °C for 20 hours. After completion of the reaction, the reaction mixture was quenched with ice water and extracted with ethyl acetate (EtOAc). The organic layer was separated, washed sequentially with water and saturated brine, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure. The residue was purified by silica gel column chromatography using ethyl acetate (EtOAc) in hexane as eluent to afford 3-chloro-2-fluoropyridine (0.639 g, 4.86 mmol, 71.9% yield) as a colorless oil. Compounds 3B'-8B' were prepared by a method similar to the synthetic procedure for compound 2B'.
References
[1] Tetrahedron Letters, 2015, vol. 56, # 44, p. 6043 - 6046
[2] Angewandte Chemie - International Edition, 2006, vol. 45, # 17, p. 2720 - 2725
[3] Patent: EP1595867, 2005, A1. Location in patent: Page/Page column 33-34
[4] Organic Letters, 2015, vol. 17, # 8, p. 1866 - 1869
[5] Patent: EP1726590, 2006, A1. Location in patent: Page/Page column 56
