Synthesis
General method: To a stirred solution of isoquinoline-N-oxide (0.1 M in anhydrous CH2Cl2), POBr3 (1.2 eq.) was slowly added under argon protection at 0 °C, followed by dropwise addition of DMF (0.5 eq.). The reaction mixture was gradually warmed to 25 °C and stirred continuously until the reaction was complete (monitored by TLC). Upon completion of the reaction, saturated aqueous sodium carbonate solution was slowly added and the pH was adjusted to 7-8. The organic and aqueous phases were separated and the aqueous phase was fully extracted with CH2Cl2. All organic phases were combined, washed with brine, dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure to obtain the crude product. The crude product was purified by fast column chromatography with the eluent of petroleum ether/ethyl acetate (100:1).
References
[1] Organic Letters, 2015, vol. 17, # 12, p. 2948 - 2951
[2] Organic Letters, 2013, vol. 15, # 4, p. 792 - 795
[3] Tetrahedron, 2016, vol. 72, # 38, p. 5762 - 5768
[4] Organic Letters, 2016, vol. 18, # 9, p. 1956 - 1959
