Synthesis
General procedure for the synthesis of 1-chloro-6,7-dimethoxyisoquinolin-1(2H)-one from 6,7-dimethoxyisoquinolin-1(2H)-one: a mixed solution of 6,7-dimethoxyisoquinolin-1(2H)-one (200 mg, 0.97 mmol) and phosphorus trichloride (0.268 mL, 2.92 mmol) in acetonitrile (5 mL) was placed in a microwave reactor at 110 °C for 5 min with stirring. Upon completion of the reaction, the reaction was quenched with saturated aqueous sodium bicarbonate solution and stirring was continued for 1 h at room temperature. The reaction mixture was filtered through a diatomaceous earth pad and washed with ethyl acetate. The filtrate was concentrated to dryness under reduced pressure. The crude product was purified by fast column chromatography with the eluent being a solvent mixture of heptane and ethyl acetate (the ratio was tapered from 1:0 to 0:1) to afford the target product, 1-chloro-6,7-dimethoxyisoquinoline, as a gel (99 mg, 45.4% yield). Mass spectrometry analysis showed m/z 224.0 [M + H]+ (ESI).
References
[1] Angewandte Chemie - International Edition, 2017, vol. 56, # 22, p. 6276 - 6279
[2] Angew. Chem., 2017, vol. 129, # 22, p. 6373 - 6376,4
[3] Bioorganic and Medicinal Chemistry Letters, 2014, vol. 24, # 14, p. 3199 - 3203
