RSC Advances
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General procedure for the synthesis of quinolines
2-(4-Chlorophenyl)-4-methylquinoline (3g).22 White solid
(38.8 mg, 51%), mp 73–74 ꢀC. 1H-NMR (500 MHz, CDCl3) d 8.16
(d, J ¼ 10.5 Hz, 1H), 8.11–8.09 (m, 2H), 7.98 (d, J ¼ 10.5 Hz, 1H),
7.74–7.70 (m, 1H), 7.65 (s, 1H), 7.57–7.53 (m, 1H), 7.49–7.47 (m,
2H), 2.74 (s, 3H); 13C-NMR (125 MHz, CDCl3) d 155.5, 147.9,
144.9, 138.0, 135.3, 130.1, 129.4, 128.8, 128.6, 126.2, 126.1,
123.5, 119.1, 18.8.
Under O2 atmosphere, a Teon-valve-sealed Schlenk tube was
charged with o-aminocinnamonitriles and arylhydrazines,
PdCl2, L1, TfOH and toluene at room temperature. The reaction
mixture was stirred for 10 minutes at room temperature for
proper mixing of the reactants, and then heated at 90 ꢀC (oil
bath) with vigorous stirring for 24 hours. Aer the reaction
equilibrium, the mixture was poured into ethyl acetate, which
was washed with saturated NaHCO3 (2 ꢁ 10 mL) and then brine
(10 mL). The aqueous layer was extracted with ethyl acetate, the
combined organic layers were dried over anhydrous Na2SO4 and
evaporated under vacuum. The residue was puried by ash
column chromatography (hexane/ethyl acetate) to afford the
desired products.
2-(4-Bromophenyl)-4-methylquinoline (3h).21 White solid
(37.5 mg, 42%), mp 66–67 ꢀC. 1H-NMR (500 MHz, CDCl3) d 8.22–
8.15 (m, 2H), 8.05–8.03 (m, 1H), 8.00–7.98 (m, 1H), 7.74–7.71
(m, 1H), 7.66–7.63 (m, 2H), 7.57–7.51 (m, 2H), 2.77–2.76 (m,
3H); 13C-NMR (125 MHz, CDCl3) d 155.3, 148.0, 145.2, 141.8,
132.1, 130.6, 130.4, 130.3, 129.6, 127.4, 126.4, 126.1, 123.7,
123.1, 119.5, 19.0.
4-Methyl-2-(4-(triuoromethyl)phenyl)quinoline
(3i).23
4-Methyl-2-phenylquinoline (3a).17 White solid (53.2 mg,
1
Yellow oil (22.4 mg, 26%). 1H-NMR (500 MHz, CDCl3) d 8.27 (d, J
¼ 8.0 Hz, 2H), 8.20 (d, J ¼ 8.5 Hz, 1H), 8.02 (d, J ¼ 8.0 Hz, 1H),
7.78–7.24 (m, 4H), 7.60–7.57 (m, 1H), 2.79 (s, 3H); 13C-NMR (125
MHz, CDCl3) d 155.5, 148.0, 145.5, 143.0, 131.0 (d, J ¼ 32.5 Hz),
130.4, 129.7, 127.9, 127.5, 126.6, 125.7 (q, J ¼ 3.8 Hz), 124.2 (d, J
¼ 270.0 Hz), 123.7, 119.6, 19.0.
ꢀ
81%), mp 62–63 C. H-NMR (500 MHz, CDCl3) d 8.22 (d, J ¼
10.5 Hz, 1H), 8.19–8.17 (m, 2H), 7.97 (d, J ¼ 10.5 Hz, 1H), 7.75–
7.70 (m, 2H), 7.56–7.52 (m, 3H), 7.49–7.46 (m, 1H), 2.73 (s, 3H);
13C-NMR (125 MHz, CDCl3) d 157.0, 148.2, 144.8, 139.8, 130.3,
129.3, 129.2, 128.8, 127.6, 127.3, 126.0, 123.6, 119.7, 19.0.
4-Methyl-2-(p-tolyl)quinoline (3b).18 Yellow oil (59.4 mg,
1
6-Methyl-2-phenylquinoline (3j).24 White solid (42.7 mg,
65%), mp 68–69 ꢀC. 1H NMR (500 MHz, CDCl3) d 8.18–8.16 (m,
2H), 8.10 (d, J ¼ 11.0 Hz, 2H), 7.82 (d, J ¼ 11.0 Hz, 1H), 7.57–7.52
(m, 4H), 7.48–7.45 (m, 1H), 2.55 (s, 3H); 13C-NMR (125 MHz,
CDCl3) d 156.5, 146.8, 139.8, 136.2, 136.1, 132.0, 129.4, 129.2,
128.8, 127.5, 127.2, 126.3, 119.0, 21.6.
85%). H-NMR (500 MHz, CDCl3) d 8.20 (d, J ¼ 10.5 Hz, 1H),
8.09–8.07 (m, 2H), 7.98 (d, J ¼ 10.0 Hz, 1H), 7.74–7.70 (m, 2H),
7.55–7.51 (m, 1H), 7.34 (d, J ¼ 10.0 Hz, 2H), 2.74 (s, 3H), 2.45 (s,
3H); 13C-NMR (125 MHz, CDCl3) d 157.0, 148.1, 144.7, 139.3,
136.9, 130.2, 129.5, 129.3, 127.4, 127.2, 125.9, 123.6, 119.6, 21.3,
19.0.
6-Methoxy-2-phenylquinoline (3k).25 White solid (36.7 mg,
4-Methyl-2-(m-tolyl)quinoline (3c).18 Yellow oil (55.2 mg,
79%). 1H-NMR (500 MHz, CDCl3) d 8.22 (d, J ¼ 8.0 Hz, 1H), 8.02–
7.98 (m, 2H), 7.94 (d, J ¼ 8.0 Hz, 1H), 7.74–7.70 (m, 2H), 7.56–
7.52 (m, 1H), 7.44–7.41 (m, 1H), 7.29 (d, J ¼ 7.5 Hz, 1H), 2.75 (s,
3H), 2.50 (s, 3H); 13C-NMR (125 MHz, CDCl3) d 157.3, 148.1,
144.7, 139.8, 138.4, 130.3, 130.0, 129.3, 128.7, 128.3, 127.3,
126.0, 124.7, 123.6, 119.9, 21.6, 19.0.
1
ꢀ
52%), mp 125–126 C. H-NMR (500 MHz, CDCl3) d 8.15–8.14
(m, 1H), 8.13 (s, 1H), 8.11 (d, J ¼ 6.0 Hz, 1H), 8.08 (d, J ¼ 6.0 Hz,
1H), 7.83 (d, J ¼ 11.5 Hz, 1H), 7.52 (dd, J1 ¼ 9.5 Hz, J2 ¼ 9.0 Hz,
2H), 7.45 (d, J ¼ 9.5 Hz, 1H), 7.39 (dd, J1 ¼ 3.5 Hz, J2 ¼ 11.5 Hz,
1H), 7.08 (d, J ¼ 3.5 Hz, 1H), 3.94 (s, 3H); 13C-NMR (125 MHz,
CDCl3) d 157.8, 155.0, 144.4, 139.8, 135.5, 131.2, 128.9, 128.8,
128.2, 127.3, 122.3, 119.2, 105.1, 55.5.
4-Methyl-2-(o-tolyl)quinoline (3d).19 Yellow oil (36.3 mg,
52%). 1H NMR (500 MHz, CDCl3) d 8.20 (d, J ¼ 8.5 Hz, 1H), 8.04–
8.03 (m, 1H), 7.76–7.73 (m, 1H), 7.60–7.57 (m, 1H), 7.51–7.49
(m, 1H), 7.39 (s, 1H), 7.37–7.31 (m, 3H), 2.76 (s, 3H), 2.43 (s, 3H);
13C-NMR (125 MHz, CDCl3) d 160.3, 147.9, 144.3, 140.5, 136.0,
130.3, 130.0, 129.6, 129.3, 128.3, 126.0, 123.6, 123.1, 20.3, 18.8.
2-(4-Fluorophenyl)-4-methylquinoline (3e).20 Yellow oil
(54.1 mg, 76%). 1H-NMR (500 MHz, CDCl3) d 8.18 (d, J ¼
10.5 Hz, 1H), 7.99 (d, J ¼ 10.5 Hz, 1H), 7.92–7.90 (m, 2H), 7.75–
7.71 (m, 1H), 7.67 (s, 1H), 7.58–7.54 (m, 1H), 7.50–7.45 (m, 1H),
7.17–7.13 (m, 1H), 2.76 (s, 3H); 13C-NMR (125 MHz, CDCl3)
d 163.8 (d, J ¼ 247.5 Hz), 155.9, 148.1, 145.0, 135.9 (d, J ¼ 2.5
Hz), 130.2, 129.4, 129.3 (d, J ¼ 7.5 Hz), 127.2, 126.1, 123.6, 119.4,
115.7 (d, J ¼ 22.5 Hz), 19.0.
6-Fluoro-2-phenylquinoline (3l).16 White solid (41.5 mg,
62%), mp 94–95 ꢀC. 1H-NMR (500 MHz, CDCl3) d 8.21–8.19 (m,
2H), 8.17–8.15 (m, 2H), 7.91 (d, J ¼ 10.5 Hz, 1H), 7.56–7.44 (m,
5H); 13C-NMR (125 MHz, CDCl3) d 160.4 (d, J ¼ 248.0 Hz), 156.7
(d, J ¼ 2.8 Hz), 145.3, 139.2, 136.2 (d, J ¼ 5.2 Hz), 132.1 (d, J ¼ 9.1
Hz), 129.5, 128.9, 127.7 (d, J ¼ 10.0 Hz), 127.5, 119.9 (d, J ¼ 25.7
Hz), 119.7, 110.5 (d, J ¼ 21.7 Hz).
7-Fluoro-2-phenylquinoline (3m).25 White solid (38.8 mg,
1
ꢀ
58%), mp 88–89 C. H-NMR (500 MHz, CDCl3) d 8.22 (d, J ¼
8.0 Hz, 1H), 8.16 (d, J ¼ 7.5 Hz, 2H), 7.86–7.80 (m, 3H), 7.56–7.53
(m, 2H), 7.50–7.47 (m, 1H), 7.34–7.30 (m, 1H); 13C-NMR (125
MHz, CDCl3) d 163.3 (d, J ¼ 249.6 Hz), 158.3, 149.3 (d, J ¼ 12.9
Hz), 139.3, 136.6, 129.6, 129.4 (d, J ¼ 10.0 Hz), 128.9, 127.6,
124.2, 118.3 (d, J ¼ 2.5 Hz), 116.7 (d, J ¼ 25.5 Hz), 113.3 (d, J ¼
20.2 Hz).
2-(3-Fluorophenyl)-4-methylquinoline (3f).21 Yellow oil
(44.8 mg, 63%). 1H-NMR (500 MHz, CDCl3) d 8.18 (m, 3H), 7.86–
7.85 (m, 1H), 7.61–7.50 (m, 2H), 7.43–7.42 (m, 1H), 7.09–7.07
(m, 2H), 2.62 (s, 3H); 13C-NMR (125 MHz, CDCl3) d 163.4 (d, J ¼
243.8 Hz), 155.5 (d, J ¼ 2.5 Hz), 148.0, 145.1, 142.1 (d, J ¼ 7.5
Hz), 130.4, 130.2 (d, J ¼ 8.8 Hz), 129.5, 127.4, 126.4, 123.6, 123.0
(d, J ¼ 3.8 Hz), 119.4, 116.0 (d, J ¼ 21.3 Hz), 114.4 (d, J ¼ 22.5
Hz), 19.0.
6-Chloro-2-phenylquinoline (3n).26 White solid (40.3 mg,
56%), mp 109–110 C. 11H-NMR (500 MHz, CDCl3) d 8.16–8.11
ꢀ
(m, 4H), 7.89 (d, J ¼ 9.0 Hz, 1H), 7.84–7.80 (m, 1H), 7.66 (d, J ¼
9.0 Hz, 1H), 7.55–7.52 (m, 2H), 7.49–7.47 (m, 1H); 13C-NMR (125
MHz, CDCl3) d 157.5, 146.6, 139.2, 135.8, 132.0, 131.3, 130.6,
129.6, 128.9, 127.7, 127.5, 126.1, 119.8.
8590 | RSC Adv., 2020, 10, 8586–8593
This journal is © The Royal Society of Chemistry 2020