Reaction Steps
To a solution of 8-diphenylphosphinoyl-2-methyl-1,2,3,4-tetrahydroquinoline (6) (1.5 g, 4.5 mmol) in dry degassed toluene (40 mL) was added degassed Et3N (3.15 mL, 22.5 mmol) followed by trichlorosilane (2.25 mL, 22.5 mmol). The mixture was stirred at 80° C. for 30 minutes before cautiously adding 2N NaOH (150 mL) and cooling down to room temperature. Products were then extracted with EtOAc, washed with water and saturated aqueous NaCl, dried (MgSO4) and evaporated to give a yellow oil. This oil was taken up in CH2Cl2 (100 mL), and filtered over silica gel (˜25 mL) eluting with further portions of CH2Cl2 (4×100 mL). The combined filtrates were then evaporated to give compound 7 (1.2 g) as a light yellow oil in 80% yield. 1H NMR (400.13 MHz, CDCl3) δ 7.4-7.3 (m, 10H, Ph-H), 6.99 (d, 1H, J=7.2 Hz, C5—H), 6.62 (ddd, 1H, J=7.2, 6.0, 1.2 Hz, C7—H), 6.52 (t, 1H, J=7.6 Hz, C6—H), 4.65 (bs, 1H, N1—H), 3.4-3.3 (m, 1H, C2—H), 2.9-2.7 (m, 2H, C4a/b—H), 2.0-1.9 (m, 1H, C3a—H), 1.6-1.5 (m, 1H, C3b—H), 1.11 (d, 3H, J=6.4 Hz, C1′—CH3) ppm; 13C NMR (100.61 MHz, CDCl3) δ 147.9 (d, J=18.2 Hz), 147.7 (d, J=18.2 Hz), 136.1 (d, J=12.1 Hz), 136.0 (d, J=13.1 Hz), 135.8 (d, J=13.1 Hz), 135.7 (d, J=13.1 Hz), 134.1-133.5 (m), 132.5 (d, J=12.1 Hz), 132.4 (d, J=12.1 Hz), 130.5, (d, J=13.1 Hz), 128.7-128.4 (m), 120.7 (d, J=12.1 Hz), 117.0, (d, J=12.1 Hz), 116.3 (d, J=12.1 Hz), 47.4, 39.6, 26.8, 22.4 ppm; 31P NMR (161.97 MHz, CDCl3) δ −21.9 ppm.
