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S.-M. Lu et al. / Journal of Organometallic Chemistry 692 (2007) 3065–3069
and [Ru(COD)Cl2]x were used as received. Iodine (Acros)
was purchased and ground before use. Quinoxaline, quino-
line and 2-methylquinoline were distilled before use. Other
quinolines derivatives were prepared from 2-methylquino-
line. The solvents used in the glovebox were purchased
(Acros) and used directly. All the solvents used under the
air were purchased (AR, Kermel company, China) and
used directly without any purification. The conversion
was determined by 1H NMR analysis recorded at
400 MHz on a Bruker DRX-400 spectrometer. Hydrogena-
tion reactions were performed with a stainless steel auto-
clave (300 mL internal volume). 1H NMR spectra were
recorded on a Bruker DRX-400 spectrometer and all chem-
ical shift values refer to dTMS = 0.00 ppm or CDCl3 (d,
7.26 ppm).
3H), 1.52 (m, 3H), 1.92 (m, 1H), 2.73 (m, 2H), 3.12 (m,
1H), 3.68 (br, 1H), 6.43 (d, J = 8.2 Hz, 1H), 6.56 (t,
J = 8.3 Hz, 1H), 6.92 (m, 2H).
2-Butyl-1,2,3,4-tetrahydroquinoline (2c) [10]: Yield:
1
82%, H NMR (400 MHz, CDCl3) 0.96 (t, J = 7.0 Hz,
3H), 1.49 (m, 7H), 1.95 (m, 1H), 2.75 (m, 2H), 3.21 (m,
2H), 3.71 (br, 1H), 6.45 (d, J = 8.2 Hz, 1H), 6.59 (m,
1H), 6.97 (m, 2H).
2-Phenethyl-1,2,3,4-tetrahydroquinoline
(2d)
[10]:
1
Yield: 83%, H NMR (400 MHz, CDCl3) 1.96 (m, 1H),
2.12 (m, 2H), 2.28 (m, 1H), 3.02 (m, 4H), 3.56 (m, 1H),
4.01 (br, 1H), 6.72 (d, J = 8.2 Hz, 1H), 6.91 (t, J = 7.3
Hz, 1H), 7.25 (m, 2H).
2-(30,40-Dimethoxyphenethyl)-1,2,3,4-tetrahydroquino-
1
line (2e) [10]: Yield: 83%, H NMR (400 MHz, CDCl3)
1.65 (m, 1H), 1.81 (m, 2H), 1.98 (m, 1H), 2.67 (m, 4H),
2.77 (m, 1H), 3.28 (m, 1H), 3.85 (s, 3H), 3.86 (s, 3H),
6.44 (d, J = 8.0 Hz, 1H), 6.59 (m, 1H), 6.74 (m, 3H), 6.94
(m, 2H).
4.2. Hydrogenation of 2-methyl-quinoline in the glovebox in
the presence of ligand
In a glovebox, to a mixture of [Ru(p-cymene)Cl2]2
(1.6 mg, 0.0025 mmol) and (rac)-MeO–BiPhep (3.2 mg,
0.0055 mmol) was added dry THF (2 mL). To another mix-
ture of I2 (6.4 mg, 0.025 mmol) and 2-methyl-quinoline
(72 mg, 0.5 mmol) was added THF (1 mL). Both of them
were stirred at room temperature for 10 min, then the
in situ prepared catalyst solution was added into the mix-
ture of I2 and substrate using a syringe. The hydrogenation
was performed at room temperature under H2 (600 psi) for
12 h. After carefully releasing the hydrogen, the reaction
mixture was concentrated and the conversion was deter-
6-Fluoro-2-mthyl-1,2,3,4-tetrahydroquinoline (2f) [10]:
Yield: 90%, H NMR (400 MHz, CDCl3) 1.13 (d, J = 6.0
Hz, 3H), 1.53 (m, 1H), 1.85 (m, 1H), 2.64 (m, 1H), 2.74
(m, 1H), 3.28 (m, 1H), 3.70 (br, 1H), 6.34 (m, 1H), 6.61
(m, 2H).
1
1-(1,2,3,4-tetrahydroquinolin-2-ylmethyl)-cyclohexanol
1
(2h) [10]: Yield: 76%, H NMR (400 MHz, CDCl3) 1.24
(m, 2H), 1.53 (m, 14H), 1.74 (m, 1H), 2.67 (m, 1H), 2.78
(m, 1H), 3.50 (m, 1H), 6.39 (m, 1H), 6.49 (m, 1H), 6.87
(m, 2H).
1,2,3,4-tetrahydroquinoline (2i) [10]: Yield: 64%, 1H
NMR (400 MHz, CDCl3) 1.93 (m, 2H), 2.76 (t, J = 6.4
Hz, 2H), 3.29 (t, J = 5.2 Hz, 2H), 3.79 (bs, 1H), 6.45 (m,
1H), 6.60 (m, 1H), 6.95 (m, 2H).
1
mined by H NMR analysis.
4.3. Typical procedure for the hydrogenation of quinolines 1
under the air
In the air, to the reaction bottle A was added [Ru(p-
cymene)Cl2]2 (1.6 mg, 0.0025 mmol) and 2 mL undistilled
THF. The mixture was stirred until the solution is homoge-
neous. At the same time, to the reaction bottle B was added
quinolines (0.5 mmol) and I2 (6.4 mg, 0.025 mmol), fol-
lowed by 1 mL THF. The mixture was stirred until the
iodine is dissolved. Then to the reaction bottle B was added
the solution of [Ru(p-cymene)Cl2]2 of THF in bottle A.
Then the resulting reaction mixture was placed in an auto-
clave. Finally the autoclave was pressurized to 600 psi
hydrogen and stirred at 20 °C for 12 h. After carefully
releasing the hydrogen, the reaction mixture was concen-
trated to afford the crude product. Purification was per-
formed by a silica gel column eluted with hexane/EtOAc
to give pure product.
Acknowledgements
We are grateful for the financial support from National
Science Foundation of China (20532050).
References
[1] (a) For reviews, see: F. Glorius, Org. Biomol. Chem. 3 (2005) 4171,
and references cited therein;
(b) S.-M. Lu, X.-W. Han, Y.-G. Zhou, Chin. J. Org. Chem. 25 (2005)
634, and references cited therein;
(c) For asymmetric hydrogenation of 2-methylquinoxaline, see: C.
Bianchini, P. Barbaro, G. Scapacci, J. Organomet. Chem. 621 (2001)
26;
(d) J.P. Henschke, M.J. Burk, C.G. Malan, D. Herzberg, J.A.
Peterson, A.J. Wildsmith, C.J. Cobley, G. Casy, Adv. Synth. Catal.
345 (2003) 300;
2-Methyl-1,2,3,4-tetrahydroquinoline (2a) [10]: Yield:
90%, 1H NMR (400 MHz, CDCl3) 1.24 (t, J = 6.5 Hz,
3H), 1.62 (m, 1H), 1.96 (m, 1H), 2.81 (m, 2H), 3.42 (m,
1H), 3.50 (br, 1H), 6.49 (d, J = 8.2 Hz, 1H), 6.63 (m 1H),
6.98 (m, 2H).
(e) C. Bianchini, P. Barbaro, G. Scapacci, E. Farnetti, M. Graziani,
Organometallics 17 (1998) 3308;
(f) C.J. Cobley, J.P. Henschke, Adv. Synth. Catal. 345 (2003) 195;
(g) , For asymmetric hydrogenation of indoles, see:R. Kuwano, K.
Sato, T. Kurokawa, D. Karube, Y. Ito, J. Am. Chem. Soc. 122
(2000) 7614;
2-Ethyl-1,2,3,4-tetrahydroquinoline (2b) [10]: Yield:
90%, 1H NMR (400 MHz, CDCl3) 0.95 (t, J = 7.6 Hz,
(h) R. Kuwano, K. Kaneda, T. Ito, K. Sato, T. Kurokawa, Y. Ito,
Org. Lett. 6 (2004) 2213;