Synthesis
General procedure for the synthesis of 6-fluoroquinoline from 6-fluoro-1,2,3,4-tetrahydroquinoline: To a 10 mL round-bottomed flask fitted with a magnetic stirring bar, 6-fluoro-1,2,3,4-tetrahydroquinoline (0.5 mmol), 40 wt% toluene solution (2.2 equiv., 1.1 mmol, 0.5 mL), and a DEAD solution of CHCl3 ( 1.0 mL). The reaction mixture was stirred at room temperature for 12 hours. After completion of the reaction, the mixture was concentrated using a rotary evaporator. The residue was purified by column chromatography using EtOAc: hexane (1:5) as eluent to give 6-fluoroquinoline. For compounds 2f and 2m, the product spot was close to the spot of residual DEAD. To remove residual DEAD, 1 equivalent of PPh3 was added after the reaction and the reaction mixture was stirred for 10 min. Subsequently, the reaction mixture was concentrated using a rotary evaporator. The residue was purified by column chromatography using CHCl3: hexane (1:1) as eluent to give the final 6-fluoroquinoline.
References
[1] Organic Letters, 2015, vol. 17, # 18, p. 4404 - 4407
[2] Angewandte Chemie - International Edition, 2017, vol. 56, # 11, p. 3080 - 3084
[3] Angew. Chem., 2017, vol. 129, # 11, p. 3126 - 3130,5
[4] Organic Letters, 2016, vol. 18, # 24, p. 6300 - 6303
[5] Synthetic Communications, 2018, vol. 48, # 11, p. 1291 - 1298
