Synthesis
The general procedure for the synthesis of 7-hydroxy-1,2,3,4-tetrahydroquinoline from 3,4-dihydro-7-hydroxy-2(1H)-quinolinone was as follows: 7-hydroxy-3,4-dihydroquinolin-2(1H)-one (2.00 g, 12.26 mmol) was dissolved in tetrahydrofuran (THF, 20 mL) and the solution was cooled down to 0 °C. Subsequently, sodium borohydride (NaBH4, 1.07 g, 28.19 mmol) was added, and then iodine (I2, 3.42 g, 13.48 mmol) dissolved in THF (20 mL) was slowly added dropwise through the addition funnel to the reaction mixture. After installing the condenser, the reaction mixture was refluxed overnight. After completion of the reaction, the reaction mixture was neutralized with 3 M hydrochloric acid solution and then extracted three times with dichloromethane. The organic layers were combined and dried with anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure to give a viscous yellow oil. Finally, the crude product was purified by fast column chromatography to afford 7-hydroxy-1,2,3,4-tetrahydroquinoline as a white crystalline solid (1.80 g, 98% yield).
References
[1] Angewandte Chemie - International Edition, 2013, vol. 52, # 2, p. 650 - 654
[2] Angew. Chem., 2013, vol. 125, # 2, p. 678 - 682,5
[3] Chinese Chemical Letters, 2018, vol. 29, # 10, p. 1497 - 1499
[4] Organic Letters, 2011, vol. 13, # 23, p. 6196 - 6199
[5] Organic and Biomolecular Chemistry, 2013, vol. 11, # 24, p. 3954 - 3962
