Chemistry
General
Reagents of the highest commercial quality were purchased and used without further purification unless otherwise specified.
Synthesis of 4-(Pyridin-4-yl) thiazol-2-amine (2)
Step 1. To a solution of 4-acetylpyridine (4.90 g, 41.30 mmol) and 48% HBr (7.0 mL) in acetic acid (46.0 mL), a solution of bromine (2.30 mL, 45.00 mmol) in acetic acid (8.0 mL) at 0 °C was added dropwise. After addition, the reaction mixture was allowed to stir at 70 °C for 1 h. The mixture was cooled to 0 °C and treated with diethyl ether. The resultant white solid was isolated by vacuum filtration to give 9.90 g (87%) of bromoketone as the HBr salt, which was used in the next step as obtained.
Step 2. A mixture of the above intermediate (10.00 g, 35.59 mmol), thiourea (2.71 g, 35.59 mmol), and absolute EtOH (100 mL) was refluxed overnight. After cooling to room temperature, the reaction mixture was diluted with water (400 mL), and the pH was adjusted to 11 with concentrated ammonium hydroxide solution and was further stirred for 2 h. The resulting precipitate was filtered, washed, and dried to provide the title compound as a yellowish solid (5.85 g, 93% yield). (m.p. 270-272 ºC) (
26).
Synthesis of 4-Methyl-N-(4-(pyridine-4-yl) thiazol-2-yl) benzamide (3)
To a solution of p-toluic acid (1.10 g, 5.64 mmol) in 10 mL DCM, EDCI (1.60 g, 8.46 mmol) and HOBt (0.76 g, 5.64 mmol) were added at room temperature. The mixture was stirred at room temperature for 30 min, then a solution of compound 2 (1.00 g, 5.64 mmol) in 10 mL DCM was added slowly. The resulting reaction mixture was stirred at room temperature for 8 h until TLC indicated that all the starting material was consumed. The reaction mixture was diluted with water and extracted with DCM. The organic phase was washed with water and brine, dried, filtered, and concentrated. The residue was purified by chromatography to afford the title compound 3 (1.62 g, 83% yield) as a yellow solid and used in the next step.
Synthesis of 5-aryl-4-aminomethyl-thiazole -2-amines (4)
To a mixture of compound 3 (1.9 g, 10.7 mmol, 1.0 equiv.), appropriate amine (1.2 equiv.) in acetic acid was paraformaldehyde (3 equiv.) at room temperature. The reaction mixture was allowed to stir at 70 °C for 1 h. After removing the extra acetic acid under reduced pressure, the residue was diluted with ethyl acetate. The solution was neutralized with saturated sodium bicarbonate. The organic layer was separated, washed with water and brine, dried, filtered, and concentrated. The residue was purified by flash chromatography to afford the title compound.
4-Methyl-N-(5-(morpholinomethyl)-4-(pyridin-3-yl) thiazol-2-yl) benzamide (4a)
White solid. m.p.198-199 °C; 1H NMR (400 MHz, CD3OD) δ: 9.29-9.30 (m, 1H, ArH), 8.94-8.98 (m, 2H, ArH), 8.21-8.25 (m, 1H, ArH), 7.91-7.93 (m, 2H, ArH), 7.37-7.39 (m, 2H, ArH), 4.86-4.92 (m, 2H, ArCH2), 3.87-3.99 (m, 4H, 2XOCH2) 3.50 (s, 2H, CH2), 3.23 (s, 2H, CH2), 2.43 (s, 3H, CH3); 13C NMR (125 MHz, DMSO-d6) δ: 164.8, 159.3, 145.6, 143.1, 142.9, 142.8, 142.3, 131.8, 128.7, 128.0, 127.7, 125.9, 116.1, 65.7, 62.5, 49.8, 49.5, 30.1, 20.5; HRMS calcd. for C21H23N4O2S [M++1] 395.1536, found 395.1533.
4-Methyl-N-(5-((4-methylpiperazin-1-yl) methyl)-4-(pyridin-3-yl) thiazol-2-yl) benz-amide (4b)
White solid. m.p. 180-182 ℃; 1H NMR (400 MHz, CD3OD) δ: 9.37 (s, 1H, ArH), 9.06 (s, 1H, ArH), 8.88 (s, 1H, ArH), 8.22 (s, 1H, ArH), 7.93 (s, 2H, ArH), 7.38 (s, 2H, ArH), 4.36 (s, 2H, ArCH2), 3.30-3.65 (m, 4H, 2XNCH2), 2.95 (s, 3H, CH3), 2.44 (s, 3H, CH3); 13C NMR (125 MHz, DMSO-d6) δ: 165.8, 158.9, 144.5, 143.8, 142.5, 141.8, 133.5, 129.7, 129.2, 128.8, 127.5, 66.8, 50.9, 48.4, 42.3, 21.6; HRMS calcd. for C22H26N5OS [M++1] 408.1853, found 408.1847.
N-(5-((i-Propyl(methyl)amino) methyl)-4-(pyridin-3-yl) thiazol-2-yl)-4-methylbenzamide (4c)
White solid. m.p. 184-185 ℃; 1H NMR (400 MHz, MeOD) δ: 8.90-8.91(m, 1H, ArH), 8.84-8.85 (m, 1H, ArH), 8.16-8.19 (m, 1H, ArH), 7.91-7.93 (m, 2H, ArH), 7.50-7.53 (m, 1H, ArH), 7.35-7.37 (m, 2H, ArH), 3.84 (s, 2H, CH2), 2.94-3.01 (m, 1H, CH), 2.43 (s, 3H, CH3), 2,23 (s, 3H, CH3), 1.05 (t, J = 6.8 Hz, 6H, 2CH3); 13C NMR (125 MHz, DMSO-d6) δ: 165.4, 157.7, 149.5, 148.8, 143.3, 142.3, 136.0, 131.3, 130.3, 129.7, 129.6, 128.7, 123.9, 53.0, 49.8, 36.9, 21.6, 18.0; HRMS calcd. for C21H25N4OS [M++1] 381.1744, found 381.1749.
3,4-Dichloro-N-(5-(morpholinomethyl)-4-(pyridin-3-yl) thiazol-2-yl) benzamide (4d)
White solid. m.p. 208-210 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.84-8.85 (m, 1H, ArH), 8.53-8.55 (m, 1H, ArH), 8.33-8.34 (m, 1H, ArH), 8.00-8.04 (m, 2H, ArH), 7.78-7.80 (m, 1H, ArH), 7.45-7.47 (m, 1H, ArH), 3.73 (s, 2H, CH2), 3.54-3.56 (m, 4H, 2XOCH2), 2.42 (m, 4H, 2XNCH2); 13C NMR (100 MHz, DMSO-d6) δ: 167.5, 151.7, 149.6, 149.1, 136.2, 136.0, 133.1, 132.3, 132.1, 131.5, 130.7, 129.3, 129.0, 124.8, 124.1, 66.8, 54.4, 53.7; HRMS calcd. for C20H19Cl2N4O2S [M++1] 449.0600, found 449.0604.
3,4-Dichloro-N-(5-((4-methylpiperazin-1-yl) methyl)-4-(pyridin-3-yl) thiazol-2-yl) benzamide (4e)
White solid. m.p. 179-181 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.84-8.85 (m, 1H, ArH), 8.53-8.55(m, 1H, ArH), 8.34-8.35 (m, 1H, ArH), 8.02-8.03 (m, 2H, ArH), 8.00-8.01(m, 1H, ArH), 7.79-7.81(m, 1H, ArH), 3.74 (s, 2H, CH2), 2.46-2.47 (m, 8H, 4XNCH2), 2.24 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ: 163.7,149.6, 149.1, 144.4, 143.3, 136.2, 136.0, 133.0, 132.1, 131.5, 131.0, 130.7, 128.9,127.7,124.1, 54.7, 53.8, 52.3, 45.3; HRMS calcd. for C 21H22Cl2N5OS [M++1] 462.0917, found 462.0911.
3,4-Dichloro-N-(5-((i-propyl(methyl)amino) methyl)-4-(pyridin-3-yl) thiazol-2-yl) benzamide (4f)
Yellow solid. m.p. 171-172 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 12.82 (br s, 1H, NH), 8.87-8.88 (m, 1H, ArH), 8.56-8.57 (m, 1H, ArH), 8.37-8.38 (m, 1H, ArH), 8.05-8.06 (m, 2H, ArH), 7.83-7.85 (m, 1H, ArH), 7.49-7.51(m, 1H, ArH), 3.80 (s, 2H, ArCH2), 2.91-2.92 (m, 1H, CH), 2.16 (s, 3H, CH3), 1.10 (s, 6H, 2CH3); 13C NMR (100 MHz, DMSO-d6) δ: 163.6, 151.3, 149.5, 149.0, 136.0, 135.9, 133.2, 132.0, 131.5, 131.2, 130.9, 130.7,128.9, 124.0, 123.0, 53.2, 49.9, 37.0, 18.1; HRMS calcd. for C20H21Cl2N4OS [M++1] 435.0808, found 435.0811.
N-(5-((4-Methylpiperazin-1-yl) methyl)-4-(pyridin-3-yl) thiazol-2-yl) benzamide (4g)
White solid. m.p. 198-199 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.83-8.84 (m, 1H, ArH), 8.53-8.54 (m, 1H, ArH), 8.05-8.08 (m, 2H, ArH), 8.00-8.03 (m, 1H, ArH), 7.58-7.60 (m, 1H, ArH), 7.45-7.53 (m, 3H, ArH), 3.73 (s, 2H, CH2), 2.49 (m, 8H, 4XNCH2), 2.25 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ: 172.6, 165.8, 157.9, 149.6, 149.1, 143.5, 136.3, 133.20, 132.5, 131.1, 129.2, 128.7, 124.1, 54.0, 53.6, 53.1, 51.3; HRMS calcd. for C21H24N5OS [M++1] 394.1696, found 394.1699.
N-(5-((dimethylamino)methyl)-4-(pyridin-3-yl) thiazol-2-yl) isonicotinamid (4h)
white solid. m. p.201-202 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.84-8.85 (m, 1H, ArH), 8.76-8.77 (m, 2H, ArH), 8.53-8.55 (m, 1H, ArH), 8.01-8.04 (m, 1H, ArH), 7.95-7.96 (m, 2H, ArH), 7.49-7.50 (m, 1H, ArH), 3.65 (s, 2H, ArCH2), 2.19 (s, 6H, CH3); 13C NMR (100 MHz, DMSO) δ: 164.4, 157.4, 150.9, 149.1, 143.1, 139.7, 136.2, 131.0, 128.6, 124.0, 122.3, 55.3, 45.5; HRMS calcd. for C17H18N5OS [M++1] 340.1154, found 340.1158.
N-(5-(morpholinomethyl)-4-(pyridin-3-yl) thiazol-2-yl) isonicotinamide (4i)
Yellow solid. m. p.185-187 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.86-8.87 (m, 1H, ArH), 8.79-8.80 (m, 2H, ArH), 8.65-8.66 (m, 1H, ArH), 8.09-8.12(m, 1H, ArH), 7.96-7.98 (m, 2H, ArH), 7.56-7.59 (m, 1H, ArH), 4.34 (s, 2H, ArCH2), 3.65-3.67 (m, 4H, 2XOCH2), 2.93-2.94 (m, 4H, 2XOCH2); 13C NMR (100 MHz, DMSO-d6) δ: 190.0, 164.8, 158.9, 150.9, 149.1, 148.9, 139.5, 137.8, 130.6, 127.2, 124.6, 122.3, 64.6, 51.8, 26.8; HRMS calcd. forC20H19N5O2S [M++1] 382.4540, found 382.4544.
N-(5-((dimethylamino)methyl)-4-(pyridin-3-yl) thiazol-2-yl)-2,3-dihydrobenzo[b] [1,4] dioxine-2-carboxamide (4j)
white solid. m. p.192-196 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.80-8.81 (m, 1H, ArH), 8.52-8.53 (m, 1H, ArH), 7.97-8.00 (m, 1H, ArH), 7.43-7.47 (m, 1H, ArH), 6.96-6.99 (m, 1H, ArH), 6.81-6.87 (m, 3H, ArH), 5.11-5.13 (m, 1H, XOCH), 4.40-4.41 (m, 2H, XOCH2), 3.62 (s, 2H, ArCH2), 2.16 (s, 6H, CH3); 13C NMR (100 MHz, DMSO-d6) δ: 166.6, 156.4, 149.5, 149.0, 143.3, 143.0, 136.1, 130.9, 124.0, 122.3, 121.9, 117.7, 117.5, 72.4, 65.0, 55.4, 45.4; HRMS calcd. for C20H21N4O3S[M++1] 397.4650, found 397.4652.
N-(4-(pyridin-3-yl)-5-(pyrrolidin-1-ylmethyl) thiazol-2-yl)-2,3-dihydrobenzo[b] [1,4] dioxine-2-carboxamide (4k)
Yellow solid. m.p.181-182 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.79-8.80 (m, 1H, ArH), 8.52-8.53 (m, 1H, ArH),7.96-7.99 (m, 1H, ArH), 7.44-7.47 (m, 1H, ArH), 6.95-6.97 (m, 1H, ArH), 6.80-6.88 (m, 3H, ArH), 5.16-5.17 (m,1H, XOCH), 4.36-4.45 (m, 2H, XOCH2), 3.69 (s, 2H, ArCH2), 3.50-3.52 (m, 4H, CH2), 2.36-2.38 (m, 4H, CH2); 13C NMR (100MHz, DMSO-d6) δ: 166.8, 149.5, 149.1, 143.4, 143.0, 136.1, 130.9, 127.5, 124.1, 122.3, 121.9, 117.6, 117.5, 72.3, 66.7, 55.4, 54.3, 53.6; HRMS calcd. forC22H23N4O3S[M++1] 423.5030, found 423.5034.
N-(5-(morpholinomethyl)-4-(pyridin-3-yl) thiazol-2-yl)-2,3-dihydrobenzo[b] [1,4] dioxine-2-carboxamide (4l)
Yellow solid. m. p. 177-179 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.81-8.82 (m, 1H, ArH), 8.51-8.53 (m, 1H, ArH), 7.97-8.00 (m, 1H, ArH), 7.43-7.47 (m, 1H, ArH), 6.96-6.98 (m, 1H, ArH), 6.81-6.88 (m, 3H, ArH), 5.11-5.13 (m,1H, XOCH), 4.40-4.42 (m, 2H, XOCH2), 3.83 (s, 2H, ArCH2), 2.46-2.48 (m, 4H, CH2), 1.66-1.67 (m, 4H, CH2); 13C NMR (100MHz, DMSO-d6) δ:166.9, 156.3, 149.5, 149.0, 143.4, 143.0, 136.0, 131.0, 124.0, 122.3, 121.9, 117.7, 117.5, 72.3, 65.0, 55.4, 54.1, 23.7; HRMS calcd. forC22H23N4O4S[M++1] 439.1362, found 439.1366.
4-Methyl-N-(5-(morpholinomethyl)-4-(pyridin-4-yl) thiazol-2-yl) benzamide (4m)
White solid. m.p. 148-149℃; 1H NMR (600 MHz, DMSO-d6) δ: 12.67 (br s, 1H, NH), 8.65-8.67 (m, 2H, ArH), 8.01-8.03 (m, 2H, ArH), 7.68-7.69 (m, 2H, ArH), 7.34-7.37 (m, 2H, ArH), 3.81 (s, 2H, ArCH2), 3.59-3.61 (m, 4H, 2XOCH2), 2.49-2.50 (m, 4H, 2XNCH2), 2.33 (s, 3H, CH3); 13C NMR (125 MHz, DMSO-d6) δ: 165.6, 157.9, 150.4, 143.6, 143.5, 142.3, 129.7, 129.6, 129.1, 128.8, 123.3, 66.8, 54.4, 53.7, 21.6; HRMS calcd. for C 21H23N4O2S [M++1] 395.1536, found 395.1533.
4-Methyl-N-(5-((4-methylpiperazin-1-yl) methyl)-4-(pyridin-4-yl) thiazol-2-yl) benzamide (4n)
White solid. m. p. 148-150 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 12.62 (br s, 1H, NH), 8.65-8.66 (m, 2H, ArH), 8.01-8.03 (m, 2H, ArH), 7.67-7.69 (m, 2H, ArH), 7.34-7.36 (m, 2H, ArH), 3.80 (s, 2H, ArCH2), 2.33-2.39 (m, 8H, 4XNCH2), 2.23 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ: 165.6, 161.4, 157.8, 150.4, 143.4, 143.3, 142.4, 129.8, 129.7, 128.7, 123.3, 55.2, 54.1, 53.2, 46.1, 21.6; HRMS calcd. for C22H26N5OS [M++1] 408.1853, found 408.1849.
3,4-Dichloro-N-(5-((4-methylpiperazin-1-yl) methyl)-4-(pyridin-4-yl) thiazol-2-yl) benzamide (4o)
Yellow solid. m.p. 201-203 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.66-8.67 (m, 2H, ArH), 8.38-8.39 (m, 1H, ArH), 8.06-8.07 (m, 1H, ArH), 7.84-7.85 (m,1H, ArH), 7.67-7.68 (m, 2H, ArH), 3.83 (s, 2H, ArCH2), 2.49 (s, 8H, 2XNCH2), 2.27 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ: 163.8, 157.5, 150.5, 147.2, 142.2, 136.0, 132.9, 132.5, 132.1, 131.5, 130.7, 129.0, 123.3, 66.8, 60.3, 54.4, 53.7; HRMS calcd. for C21H22Cl2N5OS [M++1] 462.0917, found 462.0911.
3,4-Dichloro-N-(5-(morpholinomethyl)-4-(pyridin-4-yl) thiazol-2-yl) benzamide (4p)
White solid. m.p.163-164 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.67-8.68 (m, 2H, ArH), 8.38-8.39 (m, 1H, ArH), 8.06-8.07 (m, 1H, ArH), 7.84-7.85 (m,1H, ArH), 7.67-7.68 (m, 2H, ArH), 3.83 (s, 2H, ArCH2), 3.60 (s, 4H, 2XOCH2), 2.49 (s, 4H, 2XNCH2); 13C NMR (100 MHz, DMSO-d6) δ: 163.7, 157.6, 150.4, 143.4, 142.2, 136.0, 133.0, 132.1, 131.5, 130.7, 130.3, 129.0, 123.3, 54.8, 53.9, 52.5; HRMS calcd. for C20H19Cl2N4O2S [M++1] 449.0600, found 449.0597.
N-(5-((4-Methylpiperazin-1-yl) methyl)-4- (pyridin-4-yl) thiazol-2-yl) isonicotinamide (4q)
White solid. m.p. 203-205 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 12.93 (br s, 1H, NH), 8.76-8.77 (m, 2H, ArH), 8.61-8.62 (m, 2H, ArH), 7.94-7.96 (m, 2H, ArH), 7.62-7.63 (m, 2H, ArH), 3.72 (s, 2H, ArCH2), 2.39 (m, 4H, CH2), 1.46-1.47 (m, 4H, CH2), 1.33-1.34 (m, 2H, CH2); 13C NMR (100 MHz, DMSO-d6) δ: 164.4, 157.3, 150.9, 150.4, 143.1, 142.2, 139.6, 131.3, 123.3, 122.3, 54.9, 54.6, 26.1, 24.3; HRMS calcd. for C20H22N6OS [M++1] 380.1467, found 380.1465.
N-(4-(Pyridin-4-yl)-5-(pyrrolidin-1-ylmethyl) thiazol-2-yl) isonicotinamide (4r)
White solid; m.p. 192-195℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.76-8.77 (m, 2H, ArH), 8.61-8.63 (m, 2H, ArH), 7.94-7.96 (m, 2H, ArH), 7.64-7.65 (m,1H, ArH), 3.90 (s, 2H, ArCH2), 2.53 (s, 4H, CH2), 1.69 (s, 2H, CH2); 13C NMR (100 MHz, DMSO-d6) δ: 164.5, 160.8, 151.0, 150.9, 150.5, 143.3, 142.2, 139.7, 123.2, 122.3, 54.2, 51.9, 23.8; HRMS calcd. for C19H20N5OS [M++1] 366.1383, found 366.1391.
N-(5-(morpholinomethyl)-4-(pyridin-4-yl) thiazol-2-yl) isonicotinamide (4s)
White solid. m.p.175-178℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.77-8.78(m, 2H, ArH), 8.62-8.64 (m, 2H, ArH), 7.95-7.96 (m, 2H, ArH), 7.64-7.65 (m, 2H, ArH),3.80 (s, 2H, ArCH2), 3.55-3.58 (m, 4H, 2XOCH2), 2.45-2.46 (m, 4H, 2XOCH2); 13C NMR (100MHz, DMSO-d6) δ: 164.50, 157.38, 150.99, 150.98, 150.46, 142.14, 139.59, 129.91, 123.31, 122.30, 66.76, 54.45, 53.75; HRMS calcd. forC19H20N5O2S[M++1] 382.1259, found 382.1263.
N-(5-(Morpholinomethyl)-4-(pyridine-4-yl) thiazol-2-yl) nicotinamide (4t)
White solid. m.p.178-180 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 9.17-9.18 (m, 1H, ArH), 8.74-8.75 (m, 1H, ArH), 8.62-8.63 (m, 2H, ArH), 7.37-7.39 (m,1H, ArH), 7.55-7.56 (m, 2H, ArH), 7.52-7.53 (m, 1H, ArH), 3.78 (s, 2H, ArCH2), 3.56 (s, 4H, 2XOCH2), 2.44 (s, 4H, 2XNCH2); 13C NMR (100 MHz, DMSO-d6) δ: 164.5, 157.5, 153.5, 150.4, 149.7, 143.5, 142.2, 136.4, 129.6, 128.4, 124.1, 123.3, 66.7, 54.4, 53.7; HRMS calcd. for C19H20N5O2S [M++1] 382.1332, found 382.1329.
N-(5-(Piperidin-1-ylmethyl)-4-(pyridin-4-yl) thiazol-2-yl) nicotinamide (4u)
White solid. m.p.169-171 ℃. 1H NMR (400 MHz, DMSO-d6) δ: 9.18-9.20 (m, 1H, ArH), 8.75-8.77 (m, 1H, ArH), 8.62-8.63 (m, 2H, ArH), 7.38-7.40 (m, 1H, ArH), 7.65-7.66 (m, 2H, ArH), 7.54-7.56 (m, 1H, ArH), 3.76 (s, 2H, ArCH2), 2.42 (s, 4H, 2XNCH2), 1.48-1.50 (m, 4H, 2CH2), 1.33-1.34 (m, 2H, CH2); 13C NMR (100MHz, DMSO-d6) δ: 164.5, 153.5, 150.4 (2C), 149.7(2C), 142.5, 136.4 (2C), 128.5, 124.1, 123.4, 54.9, 54.6, 26.0, 24.3; HRMS calcd. for C20H22N5OS [M++1] 380.1540, found 380.1538.
N-(5-(morpholinomethyl)-4-(pyridin-4-yl) thiazol-2-yl)-2,3-dihydrobenzo[b] [1,4] dioxine-2-carboxamide (4v)
yellow solid; m. p.178-180℃; 1H NMR (400 MHz, CD3OD) δ: 8.55-8.57 (m, 2H, ArH), 7.74-7.76 (m, 2H, ArH), 7.05-7.07 (m, 1H, ArH), 6.85-6.89 (m, 3H, ArH), 5.01-5.04 (m,1H, XOCH), 4.40-4.43 (m, 2H, XOCH2), 3.78 (s, 2H, ArCH2), 3.66-3.68 (m, 4H, CH2), 2.49-2.50 (m, 4H, CH2); 13C NMR (100MHz, CD3OD) δ: 166.8, 156.3, 148.8, 143.3, 141.9, 130.0, 123.4, 121.9, 121.7, 117.3, 117.0, 72.8, 66.6, 64.4, 54.0, 53.3; HRMS calcd. For C22H23N4O4S [M++1] 439.1362, found 439.1364.
Enzyme-based ROCK II inhibitory activity studies
The enzyme-based ROCK II inhibitory activity assay was performed using the Rho kinase assay kit (CY-1160, Cycle, Nagoya, Japan). All operation was guided by the manufacturer’s instructions. Briefly, the compounds at 10 µM were pre-incubated in a system wherein ROCK II (0.02 ng/µL) phosphorylates the myosin-binding subunit (MBS) of kinase substrate pre-absorbed onto the microplate in the presence of Mg2+ and ATP. Then, the system was washed after incubation at 30 ◦C for 30 min. 100 µL of antibody was added to the wells and then incubated for 30 min at room temperature. 100 µL of substrate reagent and 100 µL stop solution were successively added to each well. The plates were read on the Viewlux in HTRF mode within 30 min.
Molecular docking
Molecular docking was performed using the Surflex-Dock module in Sybyl 2.0 software package. The crystal structure of human ROCK II (PDB code: 4L6Q) was download from RCSB Protein Data Bank. Before the docking process, the natural co-crystallized ligand was extracted, and water molecules were removed from the crystal structure, H atoms were added, and side chains were fixed during protein preparation. Subsequently, the protein was prepared using the Biopolymer module implemented in Sybyl. Protein structure minimization was performed by applying the Tripos force field, and partial atomic charges were calculated by the Gasteiger-Huckel method. All parameters were set to default values.
Synthesis of 4-aryl-5-aminomethyl-thiazole-2-amines. Reagents and conditions: (a) 1) Br2, AcOH, 48% HBr, 2) thiourea, EtOH, reflux; (b) EDCI, HOBt, R1C6H5COOH, DIPEA, DMF, r.t.; (c) HNR2R3, (CH2O) n, AcOH, 70 ºC
Structures of Fasudil and ROCK inhibitors under clinical trials
The design of 4-aryl-5-aminoalkyl-thiazole-2-amines
(A) Predicted binding mode of compound 4v (yellow) with ROCK II (PDB ID:4L6Q); (B) Predicted binding mode of compound I (yellow) and II (blue) with ROCK II (PDB ID:4L6Q). The residues in ROCK II are shown in green sticks. Hydrogen bonds are shown as red dashed lines
| Compd. | ROCK II (µM) | Compd. | ROCK II (µM) |
|---|
| 4k | 1.56 ± 0.23 | 4t | 9.12 ± 2.46 |
| 4i | 9.83 ± 1.45 | 4l | 1.02 ± 0.07 |
| 4v | 0.02 ± 0.01 | 4j | 0.96 ± 0.12 |
| 4s | 8.56 ± 067 | II | 0.01 ± 0.003 |