Synthesis
General procedure for the synthesis of 2-fluoro-3-nitropyridine from 2-chloro-3-nitropyridine: 2-chloro-3-nitropyridine (1.00 g, 6.76 mmol) was dissolved in DMSO (33.8 ml) at room temperature, followed by addition of CsF (2.053 g, 13.51 mmol). The reaction mixture was stirred in air at 110°C for 20 hrs. After completion of the reaction, the reaction mixture was quenched with ice water and extracted with EtOAc. The organic layer was separated, washed sequentially with water and brine, dried over anhydrous Na2SO4 and concentrated under reduced pressure. Purification of the residue by column chromatography (silica gel as stationary phase and EtOAc/hexane as eluent) afforded 2-fluoro-3-nitropyridine (0.639 g, 4.86 mmol, 71.9% yield) as a colorless oil. Similarly, compounds 3B'-8B' can be prepared according to the synthesis of 2B' above.
References
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[2] Tetrahedron Letters, 2015, vol. 56, # 44, p. 6043 - 6046
[3] Heterocycles, 1986, vol. 24, # 11, p. 3213 - 3221
[4] Journal of Labelled Compounds and Radiopharmaceuticals, 2004, vol. 47, # 6, p. 373 - 383
[5] Tetrahedron, 2001, vol. 57, # 4, p. 739 - 750
