Synthesis
General method for the synthesis of 2-phenyl-1,2,3,4-tetrahydroisoquinoline (1) [3]: copper (I) iodide (0.20 g, 1.0 mmol) and potassium phosphate (4.25 g, 20.0 mmol) were added to a Schlenk tube. The Schlenk tube was evacuated and backfilled three times with nitrogen. 2-Propanol (10.0 mL), ethylene glycol (1.11 mL, 20.0 mmol), 1,2,3,4-tetrahydroisoquinoline (2.0 mL, 15 mmol), and iodobenzene (1.12 mL, 10.0 mmol) were added sequentially via microsyringe. The reaction mixture was heated and stirred at 85-90°C for 24 hours and subsequently cooled to room temperature. Diethyl ether (20 mL) and water (20 mL) were added to the reaction mixture and the organic layer was extracted with ether (2 x 20 mL). The combined organic phases were washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation and the crude product was purified by silica gel column chromatography (eluent: ethyl acetate/hexane, 1:20, v/v) to afford the target product 2-phenyl-1,2,3,4-tetrahydroisoquinoline (1). The product was a yellow viscous liquid in 75% yield. Thin layer chromatography (TLC) Rf = 0.70 (silica gel plate, ethyl acetate/hexane, 1:20).1H NMR (400 MHz, CDCl3) δ: 7.43-7.19 (m, 6H), 7.08 (d, J = 7.4 Hz, 2H), 6.92 (t, J = 6.5 Hz, 1H), 4.50 (s, 2H), 3.65 (d, J = 6.4 Hz, 2H). = 6.4 Hz, 2H), 3.08 (d, J = 5.7 Hz, 2H).13C NMR (101 MHz, CDCl3) δ: 150.66, 134.99, 134.58, 129.32, 128.64, 126.66, 126.44, 126.14, 118.78, 115.26, 50.85. 46.65, 29.25. High resolution mass spectrometry (HRMS-ESI) m/z: [M + H]+ Calculated value 210.1277, measured value 210.1269. Infrared spectra (IR, KBr) ν: 3063, 3028, 2927, 2813, 1737, 1662, 1601, 1500, 1456, 1386, 1242, 1036, 931, 752. 1036, 931, 752, 695 cm-1.
References
[1] Chemical Communications, 2017, vol. 53, # 93, p. 12536 - 12539
[2] Australian Journal of Chemistry, 2015, vol. 68, # 12, p. 1890 - 1893
[3] Advanced Synthesis and Catalysis, 2017, vol. 359, # 16, p. 2832 - 2846
[4] Journal of Molecular Catalysis A: Chemical, 2017, vol. 426, p. 398 - 406
[5] Monatshefte fur Chemie, 2017, vol. 148, # 1, p. 91 - 104
