General
All reagents were purchased from commercial sources and used without further purification. Melting points were measured in open capillaries and are uncorrected. 1H-NMR spectra were recorded in CDCl3/DMSO-d6 on a Bruker Avance 300 spectrometer; chemical shifts (δ) are reported in parts per million (ppm) relative to tetramethylsilane (TMS), used as an internal standard. Mass spectra (MS) were obtained from Agilent 1100LC/MS Spectrometry Services. All compounds were routinely checked by TLC with silica gel GF-254 glass plates and viewed under UV light at 254 nm. The reported HPLC purity is the peak area calculated using Class-VP software on a Shimadzu 2010 instrument.
Methyl 4-hydroxy-3-methoxybenzoate (2). Thionyl chloride (30.0 g, 0.50 mol) was added dropwise at room temperature to a solution of 3-methoxy-4-hydroxybenzoic acid (1, 44.3 g, 0.26 mol) in methanol (500 mL). The mixture was stirred at room temperature for 2 h and the solvent was concentrated in vacuo. The oil formed was resolved in ice-water (50 mL), and pH was adjusted to 7-8 with saturated aqueous sodium bicarbonate solution. The solution was left standing in the refrigerator overnight, then the precipitate was collected by filtration, and air dried to give as brown power (49.0 g, 98% yield, 97.2% HPLC purity); 1H-NMR (CDCl3): 3.89 (s, 3H), 3.91 (s, 3H), 6.09 (s, 1H), 6.92 (d, J = 8.4 Hz, 1H), 7.55 (s, 1H), 7.62 (d, J = 8.3 Hz, 1H); 13C-NMR (CDCl3): 51.94, 56.08, 111.75, 114.07, 122.24, 124.17, 146.16, 150.12, 166.88; MS (ES) m/z 183.1 (M+1).
Methyl 4-(3-chloropropoxy)-3-methoxybenzoate (3). A mixture of methyl 4-hydroxy-3-methoxy- benzoate (2, 48.0 g, 0.26 mol), 1-bromo-3-chloropropane (50.0 g, 0.32 mol), and potassium carbonate (50.0 g, 0.36 mol) in DMF (125 mL) was heated at 70 ºC for 1 h. The reaction mixture was cooled to room temperature, and then poured slowly into ice-water (1.5 L) while stirring constantly. The solid formed was filtered off and washed with cold water. The off-white product was recrystallized from ethyl acetate (120 mL) to afford 3 (61.3 g, 90% yield, 99.3% HPLC purity); 1H-NMR (CDCl3): 2.29–2.33 (m, 2H), 3.77 (t, J = 6.2 Hz, 2H), 3.89 (s, 3H), 3.91 (s, 3H), 4.22 (t, J = 6.0 Hz, 2H), 6.89 (d, J = 8.5 Hz, 1H), 7.55 (d, J = 2.0 Hz, 1H), 7.67 (dd, J = 2.0 Hz, 1H); 13C-NMR (CDCl3): 32.02, 41.36, 51.93, 55.98, 65.41, 111.83, 112.46, 122.95, 124.43, 148.94, 152.16, 166.78; MS (ES) m/z 259.1 (M+1).
Methyl 4-(3-chloropropoxy)-5-methoxy-2-nitrobenzoate (4). Nitric acid (84.5 mL, 66%) was added dropwise at room temperature to a solution of methyl 4-(3-chloropropoxy)-3-methoxybenzoate (3, 51.6 g, 0.20 mol) in a mixture of acetic acid (150 mL). This mixture was stirred at 60 ºC for 3–4 h. Then the mixture was washed with ice-water (2 × 50 mL). The organic layer was washed with saturated sodium bicarbonate to neutrality. The oil formed was stirred till solidified and then collected by filtration to afford the product as light yellow solid (54.0 g, 89% yield, 98.7% HPLC purity); 1H-NMR (CDCl3): 2.28–2.42 (m, 2H), 3.77 (t, J = 6.2 Hz, 2H), 3.91 (s, 3H), 3.96 (s, 3H), 4.24 (t, J = 6.0 Hz, 2H), 7.08 (s, 1H), 7.49 (s, 1H); 13C-NMR (CDCl3): 31.82, 41.00, 53.21, 56.54, 66.03, 108.32, 111.02, 121.89, 141.08, 149.54, 152.84, 166.25; MS (ES) m/z 304.1 (M+1).
Methyl 2-amino-4-(3-chloropropoxy)-5-methoxybenzoate (5). Powdered iron (5.6 g, 0.10 mol) and ammonium chloride (8.4 g, 0.157 mol) were added to a mixture of methanol (70 mL) and water (30 mL). The resulting suspension was heated at reflux for 10 min, then a solution of methyl 4-(3-chloropropoxy)-5-methoxy-2-nitrobenzoate (4, 9.1 g, 0.03 mol) in heated methanol (100 mL) was added dropwise. The mixture was heated at reflux for 4 h. The catalyst was filtered, and the methanol was evaporated from the filtrate. The residue was air dried to afford the product as white solid (7.5 g, 91.5% yield, 98.2% HPLC purity); 1H-NMR (CDCl3): 2.26–2.34 (m, 2H), 3.73 (t, J = 6.2 Hz, 2H), 3.80 (s, 3H), 3.85 (s, 3H), 4.15 (t, J = 6.0 Hz, 2H), 5.58(s, 2H), 6.18 (s, 1H), 7.31 (s, 1H); 13C-NMR (CDCl3): 31.94, 41.43, 51.33, 56.70, 65.11, 100.58, 102.51, 113.65, 140.85, 146.97, 154.17, 168.10; MS (ES) m/z 274.1(M+1).
(E)-Methyl 4-(3-chloropropoxy)-2-(2-cyanovinylamino)-5-methoxybenzoate (6). 3,3-Diethoxy- propionitrile (2 mL, 13.34 mmol), trifluoroacetic acid (4 mL) and water (1 mL) were stirred for 6 h at 5–10 ºC under an atmosphere of N2, and then a solution of methyl 2-amino-4-(3-chloro- propoxy)-5-methoxybenzoate (5, 2.0 g, 7.32 mmol) in ethyl acetate (8 mL) was added. The mixture was stirred for 10 min. The solid formed was filtered off and air dried to afford the product as light yellow solid (2.0 g, 84.3% yield, 98.7% HPLC purity); 1H-NMR (CDCl3): 2.31–2.39 (m, 2H), 3.79 (t, J = 6.2 Hz 2H), 3.85 (s, 3H), 3.90 (s, 3H), 4.26 (t, J = 6.0 Hz, 2H), 4.68(d, J = 6.8 Hz, 2H), 6.58(s, 1H), 7.42 (s, 1H), 7.53 (t, J = 17.7 Hz, 1H), 10.55 (d, J = 6.5 Hz, 1H); 13C-NMR (CDCl3): 31.87, 41.15, 51.11, 56.37, 65.61, 71.96, 97.65, 105.26, 113.52, 117.41, 138.63, 142.95, 144.17, 153.94, 168.18; MS (ES) m/z 324.9 (M+1).
7-(3-Chloropropoxy)-4-hydroxy-6-methoxyquinoline-3-carbonitrile (7). A solution of (E)-methyl 4-(3-chloropropoxy)-2-(2-cyanovinylamino)-5-methoxybenzoate (6, 1.5 g, 4.36 mmol) in ethanol (20 mL), the pH was adjusted to 12–13 with sodium hydroxide. And then the solution was stirred at room temperature for 6 h, the solution was adjusted to nurture with water. The solid formed was filtered off and air dried to afford light yellow solid (1.16 g, 85.8% yield, 98.6% HPLC purity); 1H-NMR (CDCl3): 2.25–2.27 (m, 2H), 3.81 (t, J = 3.0 Hz, 2H), 3.88 (s, 3H), 4.20 (t, J = 3.7 Hz, 2H), 7.09(s, 1H), 7.48 (s, 1H), 8.59 (t, 1H), 12.53 (s, 1H); 13C-NMR (CDCl3): 31.56, 41.17, 56.03, 65.47, 93.78, 101.01, 104.89, 115.35, 119.99, 134.88, 144.49, 147.89, 152.14, 154.56; MS (ES) m/z 293.0 (M+1).
4-Chloro-7-(3-chloropropoxy)-6-methoxyquinoline-3-carbonitrile (8). A mixture of 7-(3-chloro- propoxy)-4-hydroxy-6-methoxyquinoline-3-carbonitrile (7, 1.0 g, 3.42 mmol) and phosphorus oxychloride (4.7 g, 30.10 mmol) in toluene (10 mL) was heated at reflux for 2 h. The solution was concentrated, and the pH was adjusted to 7 with saturated aqueous sodium bicarbonate. The resultant precipitate was collected by filtration to provide 8 (0.98 g, 92.4% yield, 98.1% HPLC purity); 1H-NMR (CDCl3): 2.36–2.44 (m, 2H), 3.81 (t, J = 6.2 Hz, 2H), 4.06 (s, 3H), 4.37 (t, J = 6.0 Hz, 2H), 7.42(s, 1H), 7.46 (s, 1H), 8.78 (s, 1H), 12.53 (d, s, 1H); 13C-NMR (CDCl3): 31.69, 41.13, 56.35, 65.62, 97.78, 102.06, 109.30, 113.57, 115.35, 142.96, 144.15, 148.19, 152.14, 154.64; MS (ES) m/z 311, 313 (M+1).
7-(3-Chloropropoxy)-4-(2,4-dichloro-5-methoxyphenylamino)-6-methoxyquinoline-3-carbonitrile (9). A mixture of 2,4-dichloro-5-methoxyaniline (0.54 g, 2.80 mmol), pyridine hydrochloride (0.276 g, 2.44 mmol), and 4-chloro-7-(3-chloropropoxy)-6-methoxyquinoline-3-carbonitrile (8, 0.80 g, 2.56 mmol) in 2-ethoxyethanol (10 mL) was heated at reflux for 2.5 h. The reaction mixture was partitioned between ethyl acetate and saturated aqueous sodium bicarbonate. The organic layer was washed with water, filtered, and concentrated in vacuo until a solid began to appear. This solid was collected by filtration to provide an off-white solid (0.68 g, 60.2% yield, 99.0% HPLC purity); 1H-NMR (DMSO-d6): 2.22–2.33 (m, 2H), 3.83 (t, J = 6.0 Hz, 2H), 3.86 (s, 3H), 3.95 (s, 3H), 4.29 (t, J = 6.0 Hz 2H), 7.34 (s, 1H), 7.37 (s, 1H), 7.75 (s, 1H), 7.85 (s, 1H), 8.42 (s, 1H), 9.64 (s, 1H); 13C-NMR (CDCl3): 31.75, 41.18, 55.52, 56.35, 65.62, 85.91, 102.06, 104.24, 109.30, 111.57, 116.57, 117.43, 132.34, 135.49, 144.92, 148.14, 150.16, 152.14, 154.64, 155.32 MS (ES) m/z 465.8, 467.8 (M+1).
4-(2,4-Dichloro-5-methoxyphenylamino]-6-methoxy-7-[3-(4-methylpiperazin-1-yl)propoxy]quinoline-3-carbonitrile (10). A mixture of 7-(3-chloropropoxy)-4-(2,4-dichloro-5-methoxyphenyl- amino)-6-methoxyquinoline-3-carbonitrile (9, 0.328 g, 0.7 mmol) and sodium iodide (0.11 g, 0.70 mmol) in N-methylpiperazine (4 mL) was heated at 80 ºC for 12 h. The reaction mixture was concentrated in vacuo and partitioned between ethyl acetate and saturated aqueous sodium bicarbonate. The organic layer was washed with brine, dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was purified by column chromatography, eluting with 30% methanol in dichloromethane. The fractions containing product were collected and concentrated in vacuo. Diethyl ether was added to the residue, and the light pink solid was collected by filtration (0.28 g, 75% yield, 98.7% HPLC purity): m.p. 116–120 ºC; 1H-NMR (DMSO-d6): 1.92–1.97 (m, 2H), 2.15 (s, 3H), 2.32–2.46 (m, 10H), 3.84 (s, 3H), 3.93 (s, 3H), 4.19 (t, J = 6.3 Hz, 2H), 7.31 (br s, 2H), 7.43 (s, 1H), 7.64 (s, 1H), 8.52 (s, 1H), 9.51 (s, 1H); 13C-NMR (CDCl3): 25.96, 45.68, 52.67, 52.67, 54.24, 54.72, 54.72, 56.01, 60.71, 66.87, 89.10, 101.66, 101.66, 109.12, 113.95, 117.17, 122.99, 122.99, 128.27, 137.88, 146.15, 148.13, 148.51, 149.50, 150.43, 153.03; MS (ES) m/z 530.2, 532.2 (M+1).