Chemistry
Melting points are uncorrected and were find out in open capillary tubes in sulphuric acid bath. TLC was carrying out on silica gel-G, and spotting was done using UV light. IR spectra were recorded using Perkin-Elmer 1000 instrument in KBr phase, The 1H NMR spectra were record on a Varian as 400 MHz instrument in DMSO, chemical shifts are given in δ ppm relative to TMS, and coupling constants (J) are expressed in hertz (Hz). Combinations of the following abbreviations are used to describe NMR spectra: s-singlet; d-doublet; t-triplet; m-multiplet. 13C NMR spectra were recorded with a Bruker Advance 400 (100 MHz) spectrometer. Mass spectra on Agilent LC–MS instrument giving only (M++H) values.
5-((2-Benzoylbenzofuran-5-yl)methyl)-2-hydroxybenzaldehyde (3a)
The mixture of 3g compound 2 (0.015 mmol), 1.51 g phenacyl bromide (0.007 mmol), and 3.10 g K2CO3 (0.022 mmol, 1.5 eq) was stirred in acetone (15 cm3) at room temperature for 12 h [24]. The completion of the reaction was monitored by TLC; the product was washed with water (15–25 cm3) and extracted from ethyl acetate. The pure compound 3 was separated through column chromatography using petroleum ether/ethyl acetate (70:30, v/v) as white solid (2.7 g, 90%). m.p.: 120–125 °C; 1H NMR (400 MHz, CDCl3): δ = 10.95 (s, 1H, Ar–CHO), 9.85 (s, 1H, OH), 8.03 (d, 2H, J = 7.93 Hz, Ar–H), 7.66–7.46 (m, 4H, Ar–H), 7.40–7.30 (m, 5H, Ar–H), 6.95 (d, 2H, J = 8.39 Hz, Ar–H), 3.98 (s, 2H, –CH2–) ppm; 13C NMR (100 MHz, CDCl3): δ = 191.3, 182.1, 159.2, 154.0, 151.4, 137.9, 137.3, 136.8, 135.3, 132.3, 132.1, 130.9, 129.8 (2C), 128.7 (2C), 126.9, 123.0, 122.0, 117.4, 117.1, 112.1, 42.0 ppm; IR (KBr): \(\bar{\nu }\) = 3550, 2800, 1650, 1579, 1720 cm−1; MS (ESI+): m/z = 357.1 ([M+H]+); and HRMS m/z calcd for C23H17O4 ([M+H]+) 357.11214, found 357.11204.
5-((2-(4-Chlorobenzoyl)benzofuran-5-yl)methyl)-2-hydroxybenzaldehyde (3b)
A mixture of 3g compound 2 (0.012 mmol, 1 eq), 1.386 g phenacyl bromide (0.06 mol, 0.5 eq), and 2.48 g K2CO3 (0.018 mol, 1.5 eq) was stirred in acetone (15 cm3) at a room temperature for 24 h. After completion of the reaction as indicated by TLC, the reaction mixture was filtered and washed with acetone (3–15 cm3). The filtrate was concentrated and the residue was chromatographer on silica gel (petroleum ether:ethyl acetate 70:30, v/v) to afford the compounds (3b) as white solid (2.46 g, 82%). m.p.: 128–130 °C; 1H NMR (400 MHz, CDCl3): δ = 10.95 (s, 1H, Ar–CHO), 9.85 (s, 1H, Ar–OH), 8.05 (d, 2H, J = 7.93 Hz, Ar–H), 7.66–7.25 (m, 6H, Ar–H), 6.90 (d, 2H, J = 8.39 Hz, Ar–H), 3.97 (s, 2H, –CH2–) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 191.2 (CHO), 182.1 (CO), 159.9 (C–OH), 154.3, 138.4, 137.5 (3C), 136.8, 134.4, 132.3, 131.1 (2C), 129.8, 128.2 (2C), 127.4, 123.5, 117.6, 112.4, 41.7 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3550, 2850, 1650, 1729 cm−1; MS (ESI+): m/z = 391.09 ([M+H]+), 413.0; and HRMS m/z calcd for C23H16ClO4 ([M+H]+) 391.07341, found 391.07316.
General procedure of the synthesized benzimidazole derivatives (4a–u)
o-Phenylenediamine, 0.068 g (0.632 mmol), was slowly added to a solution of 0.150 g (0.421 mmol) of 5-((2-benzoylbenzofuran-5-yl)methyl)-2-hydroxybenzaldehyde (3a) in glacial acetic acid, and the mixture was refluxed (70 °C) for 4–6 h under N2 atmosphere, the progress of the reaction being monitored by TLC. The mixture was cooled to room temperature, then, the mixture was poured into ice cold water and neutralised with sodium bicarbonate solution, after the mixture was washed with water and DCM for two times, the DCM layer was separated and dried over anhydrous sodium sulphate. Fatherly DCM solvent was removed in vacuo, the residue was purified by column chromatography on silica gel to give the corresponding products 4a. The other compounds 4b–u was also prepared by the similar procedure.
(5-(3-(1H-Benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4a)
From 0.150 g compound 3a (0.421 mmol, 1 eq), and 0.068 g and amine (0.632 mmol, 1.5 eq), the compound 4a was obtained as white solid (0.13 g, 87%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (80:20, v/v). m.p.: 236–240 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.18 (s, 1H, NH), 12.53 (s, 1H, Ar–OH), 8.0 (t, 2H, J = 7.28 Hz, Ar–H), 7.77–7.45 (m, 8H, Ar–H), 7.33–7.21 (m, 5H, Ar–H), 7.00 (t, 2H, J = 8.53 Hz), 4.05 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.3 (C=O), 158.3, 155.8, 153.4 (N–C–N), 151.6 (C–OH), 141.2 (2C), 138.6, 137.9, 135.3, 132.5, 131.0, 129.8 (2C) 129.5, 128.7 (2C), 123.9, 122.9 (2C), 119.0, 117.2, 118.6, 117.3, 117.2, 112.2 (2C), 41.9 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3580, 3420, 1740, 1665, 1597 cm−1; MS (ESI+): m/z = 445.08 ([M+H]+); and HRMS: m/z calcd for C29H21N2O3 ([M+H]+) 445.180721, found 445.180745.
(5-(3-(5-Bromo-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4b)
From 0.200 g compound 3a (0.561 mmol, 1 eq), and 0.157 g amine (0.842 mmol, 1.5 eq), the compound 4b was obtained as brown solid (0.16 g, 83%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 235–238 °C; 1H NMR (400 MHz, DMSO-d6): δ = 12.96 (s, 1H, NH), 12.49 (s, 1H, Ar–OH), 8.02 (d, 2H, J = 7.17 Hz, Ar–H), 7.84 (s, 1H, Ar–H), 7.62–7.29 (m, 10H, Ar–H), 7.02 (d, 1H, J = 8.3 Hz, Ar–H), 4.12 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.3 (C=O), 156.5, 154.0, 152.9 (N–C–N), 151.3 (C–OH), 140.9, 140.3, 13.0, 137.7, 135.5, 132.6, 131.9 (2C), 130.7 (2C), 128.6 (2C), 126.9, 124.7, 119.8, 118.9, 115.6, 117.9 (2C), 116.5, 112.1, 42.6 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3480, 3415, 1740, 1659, 1584 cm−1; MS (ESI+): m/z = 423.14 ([M+H]+); and HRMS: m/z calcd for C29H20BrN2O3 ([M+H]+) 423.13940, found 423.13905.
(5-(4-Hydroxy-3-(5-methyl-1H-benzo[d]imidazol-2-yl)benzyl)benzofuran-2-yl)(phenyl)methanone (4c)
From 0.180 g compound 3a (0.505 mmol, 1 eq), and 0.093 g amine (0.758 mmol, 1.5 eq), the compound 4c was obtained as brick red solid (0.14 g, 82%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 240–245 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.07 (s, 1H, NH), 11.76 (s, 1H, OH), 7.99 (d, 2H, J = 6.7 Hz, Ar–H), 7.77 (s, 1H, Ar–H), 7.75–7.68 (m, 4H, Ar–H), 7.63–7.48 (m, 5H, Ar–H), 7.43 (s, 1H, Ar–H), 7.26 (t, 1H, J = 8.28 Hz, Ar–H), 7.10 (d, 2H, J = 8.5 Hz, Ar–H), 6.99 (s, 1H, Ar–H), 4.10 (s, 2H, CH2), 2.45 (s, 3H, CH3) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.2 (C=O), 156.9, 154.2, 153.2 (N–C–N), 151.8 (C–OH), 141.6 (2C), 138.9, 137.9, 136.7, 132.8, 131.2, 129.8, 128.4 (2C), 126.0, 122.1, 121.6, 119.4, 118.6, 117.2, 117.3, 112.5 (2C), 112.1, 42.3 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3469, 3423, 1720, 1622, 1569 cm−1; MS (ESI+): m/z = 459.1 ([M+H]+), and HRMS: m/z calcd for C30H23N2O3 ([M+H]+) 459.11540, found 459.11505.
(5-(3-(5,6-Dichloro-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4d)
From 0.200 g compound 3a (0.561 mmol, 1 eq), and 0.148 g amine (0.842 mmol, 1.5 eq), the compound 4d was obtained as white solid (0.15 g, 75%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (80:20, v/v). m.p.: 2245–250 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.20 (s, 1H, NH), 12.21 (s, 1H, OH), 8.05–7.96 (m, 4H, Ar–H), 7.78–7.68 (m, 4H, Ar–H), 7.94–7.81 (t, 2H, J = 7.78 Hz, Ar–H), 7.76 (s, 1H, Ar–H), 7.30 (t, 2H, J = 6.02 Hz, Ar–H), 7.02 (d, 1H, J = 8.51, Ar–H) 4.04 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.3 (C=O), 157.9, 156.8, 153.0, 151.8 (C–OH), 140.0, 138.7, 134.6, 131.9, 131.7, 131.0, 130.9 (2C), 129.7 (3C), 128.6 (2C), 126.9 (2C), 12.9, 121.7, 117.3, 117.0 (2C), 116.9, 116.5, 112.1, 42.3 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3415, 1720, 1569 cm−1; MS (ESI+): m/z = 445.0 ([M+H]+), and HRMS: m/z calcd for C29H19Cl2N2O3 ([M+H]+) 445.09540, found 445.09515.
(5-(4-Hydroxy-3-(6-nitro-1H-benzo[d]imidazol-2-yl)benzyl)benzofuran-2-yl)(phenyl)methanone (4e)
From 0.200 g compound 3a (0.561 mmol, 1 eq), and 0.129 g amine (0.842 mmol, 1.5 eq), the compound 4e was obtained as yellow solid (0.16 g, 83%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 230–235 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.74 (s, 1H, NH), 11.81 (s, 1H, OH), 8.3 (d, 2H, J = 8.1 Hz, Ar–H), 7.99–7.76 (m, 4H, Ar–H), 7.72–7.69 (m, 5H, Ar–H), 7.65 (d, 3H, Ar–H) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.3 (C=O), 156.9, 155.8, 152.9 (N–C–N), 150.2 (C–OH), 147.9, 143.7 (C–NO2), 139.8, 138.2, 137.9, 134.6, 131.9, 130.0, 129.7 (3C), 128.5 (2C), 123.9, 119.8, 118.9, 118.4, 116.9, 116.2, 113.0, 112.0, 42.0 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3510, 3450, 1785, 1665, 1587 cm−1; MS (ESI+): m/z = 490.0 ([M+H]+), and HRMS: m/z calcd for C29H20N3O5 ([M+H]+) 490.10145, found 490.10175.
(5-(3-(5-Fluoro-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4f)
From 0.180 g compound 3a (0.505 mmol, 1 eq), and 0.092 g amine (0.758 mmol, 1.5 eq), the compound 4f was obtained as off white solid (0.15 g, 85%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 235–238 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.21 (s, 1H, NH), 12.52 (s, 1H, OH), 8.02 (d, 3H, J = 7.2 Hz, Ar–H), 7.80–7.41 (m, 8H, Ar–H), 7.42–6.89 (m, 4H, Ar–H), 4.01 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.1 (C=O), 159.1, 156.7, 154.1, 153.1, 151.4 (C–OH), 144.2, 137.9, 137.5, 136.7, 135.5, 132.4, 132.0, 131.9, 131.0, 129.8 (2C), 128.7 (2C), 128.3, 125.4 (2C), 119.7, 118.5, 117.4, 117.3, 117.1, 112.1, 109.9, 102.3, 42.1 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3453, 3405, 2550, 1735, 1655, 1587 cm−1; MS (ESI+): m/z = 463.1 ([M+H]+); and HRMS: m/z calcd for C29H20FN2O3 ([M+H]+) 463.14446, found 463.14142.
(5-(3-(5,6-Dimethyl-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4g)
From 0.250 g compound 3a (0.702 mmol, 1 eq), and 0.145 g amine (1.053 mmol, 1.5 eq), the compound 4g was obtained as brick red solid (0.187 g, 75%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 250–255 °C; 1H NMR (400 MHz, DMSO-d6): δ = 12.95 (s, 1H, NH), 9.81 (s, 1H, OH), 8.01–7.90 (m, 4H, Ar–H), 7.77–7.65 (m, 7H, Ar–H), 7.53–7.17 (m, 3H, Ar–H), 6.95 (s, 1H, Ar–H), 4.10 (s, 2H, CH2), 2.31 (s, 6H, CH3) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.0 (C=O), 156.4, 154.0, 152.6 (N–C–N), 151.5 (C–OH), 142.8 (2C), 138.9, 137.7, 136.7, 132.1, 131.9, 129.1, 128.6 (2C), 126.1, 122.9, 122.5, 119.4, 118.6, 117.2, 117.0, 112.5 (2C), 112.1, 45.2, 21.0 (2C) ppm; IR (KBr): \(\bar{\nu }\) = 3480, 3413, 2550, 1724, 1645, 1567 cm−1; MS (ESI+): m/z = 473.2 ([M+H]+); and HRMS: m/z calcd for C31H25N2O3 ([M+H]+) 473.18430, found 473.18597.
(5-(3-(5-Chloro-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4h)
From 0.200 g compound 3a (0.561 mmol, 1 eq), and 0.199 g amine (0.842 mmol, 1.5 eq), the compound 4h was obtained as off white color solid (154 g, 78%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 235–240 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.12 (s, 1H, NH), 11.59 (s, 1H, OH), 8.02 (d, 2H, J = 7.5 Hz, Ar–H), 7.66–7.15, (m, 11H, Ar–H), 6.91 (d, 2H, J = 7.25 Hz, Ar–H), 3.94 (s, 2H, –CH2–) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.0 (C=O), 156.5, 155.1, 152.9, 150.1 (C–OH), 140.2, 138.9, 137.7, 132.9, 132.6, 131.9, 131.0, 129.2, 129.7 (2C), 127.6 (2C), 124.9, 119.2, 118.1, 115.3 (2C), 112.1, 107.9, 101.8, 42.3 ppm; IR (KBr): \(\bar{\nu }\) = 3458, 3430, 2570, 1775, 1655, 1597 cm−1; MS (ESI+): m/z = 509.21 ([M+H]+); and HRMS: m/z calcd for C29H20ClN2O3 ([M+H]+) 509.19560, found 509.19515.
(5-(3-(1H-Benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(4-chlorophenyl)methanone (4i)
From 0.200 g compound 3b (0.512 mmol, 1 eq), and 0.083 g amine (0.769 mmol, 1.5 eq), the compound 4i was obtained as white solid (0.168 g, 84%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 240–242 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.32 (s, 1H, NH), 12.02 (s, 1H, OH), 8.0 (t, 2H, J = 7.28 Hz, Ar–H), 7.79 (s, 1H, Ar–H), 7.77–7.45 (m, 8H, Ar–H), 7.33–7.21 (s, 1H, Ar–H), 7.00 (t, 2H, J = 8.53 Hz, Ar–H), 4.05 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.9 (C=O), 56.8, 154.5, 152.1, 151.9 (C–OH), 141.7 (2C), 138.0, 137.2, 135.7, 133.4, 132.6, 131.4 (3C), 129.6, 129.1 (2C), 127.5, 126.6 (2C), 123.4, 117.7, 117.5 (2C), 113.0 (2C), 112.6, 43.8 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3580, 3423, 2570, 1740, 1565, 1597 cm−1; MS (ESI+): m/z = 478.09 ([M+H]+); and HRMS: m/z calcd for C29H20ClN2O3 ([M+H]+) 478.10960, found 478.10944.
(5-(3-(6-Bromo-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(4-chlorophenyl)methanone (4j)
From 0.150 g compound 3b (0.384 mmol, 1 eq), and 0.106 g amine (0.576 mmol, 1.5 eq), the compound 4j was obtained as white solid (0.124 g, 83%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (70:30, v/v). m.p.: 235–240 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.00 (s, 1H, NH), 12.75 (s, 1H, OH), 8.02 (d, 2H, J = 7.17 Hz, Ar–H), 7.66 (s, 1H, Ar–H), 7.62–7.35 (m, 9H, Ar–H), 6.92 (d, 1H, J = 8.8 Hz, Ar–H), 4.13 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.2 (C=O), 156.7, 155.1, 153.9 (N–C–N), 150.8 (C–OH), 139.9 (2C), 138.0, 137.9 (2C), 134.6, 132.7, 131.0 (3C), 129.7 (2C), 126.0, 121.2, 119.9, 116.9 (2C), 116.8, 112.5, 109.6, 102.9, 42.3 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3580, 3425, 2570, 1740, 1560, 1585 cm−1; MS (ESI+): m/z = 557.0 ([M+H]+); and HRMS: m/z calcd for C29H19BrClN2O3 ([M+H]+) 557.01960, found 557.01944.
(4-Chlorophenyl)(5-(4-hydroxy-3-(6-methyl-1H-benzo[d]imidazol-2-yl)benzyl)benzofuran-2-yl)methanone (4k)
From 0.180 g compound 3b (0.461 mmol, 1 eq), and 0.084 g amine (0.692 mmol, 1.5 eq), the compound 4k was obtained as brown solid (0.153 g, 85%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (80:20, v/v). m.p.: 250–255 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.04 (s, 1H, NH), 11.55 (s, 1H, OH), 8.01 (d, 2H, J = 6.7 Hz, Ar–H), 7.79 (s, 1H, Ar–H), 7.74–7.49 (m, 7H, Ar–H), 7.38 (s, 1H, Ar–H), 7.26 (d, 1H, J = 8.03 Hz, Ar–H), 7.09 (t, 1H, J = 4.08 Hz, Ar–H), 6.97 (s, 1H, Ar–H), 4.10 (s, 2H, CH2), 2.45 (s, 3H, CH3) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.9 (C=O), 156.8, 152.1, 152.0, 151.6 (C–OH), 138.0, 137.2, 136.4, 135.8, 133.4, 132.6, 132.4, 131.4 (3C), 130.2 (2C), 129.6, 126.7, 123.4, 117.7, 117.5, 116.9, 113.0, 112.6, 43.6 (–CH2–), 21.5 (–CH3) ppm; IR (KBr): \(\bar{\nu }\) = 3395, 2700, 1720, 1622, 1570 cm−1; MS (ESI+): m/z = 493.10 ([M+H]+); and HRMS: m/z calcd for C30H23ClN2O3 ([M+H]+) 493.10960, found 493.10904.
(4-Chlorophenyl)(5-(3-(5,6-dichloro-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl) benzo furan-2-yl)methanone (4l)
From 0.200 g compound 3b (0.512 mmol, 1 eq), and 0.134 g amine (0.769 mmol, 1.5 eq), the compound 41 was obtained as brick red solid (0.17 g, 85%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (70:30, v/v). m.p.: 250–255 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.20 (s, 1H, NH), 12.00 (s, 1H, OH), 8.05 (d, 3H, J = 8.2 Hz, Ar–H), 7.79 (s, 1H, Ar–H), 7.74–7.63 (m, 4H, Ar–H), 7.50 (d, 1H, J = 8.2, Ar–H), 7.30 (d, 1H, J = 8.2, Hz, Ar–H), 7.01 (d, 1H, J = 8.2 Hz, Ar–H), 4.10 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.2 (C=O), 156.8, 155.2, 153.1, 150.0 (C–OH), 139.5, 136.4, 135.9, 130.9, 131.1 (3C), 130.2 (2C), 129.5 (C), 129.0 (2C), 128.6 (2C), 124.2 (C), 119.5 (C), 118.0, 117.3 (2C), 116.0, 112.0 (C), 43.0 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3423, 2500, 1720, 1622, 1595 cm−1; MS (ESI+): m/z = 547.10 ([M+H]+); and HRMS: m/z calcd for C30H18ClN2O3 ([M+H]+) 547.11960, found 547.11904.
(4-Chlorophenyl)(5-(4-hydroxy-3-(6-nitro-1H-benzo[d]imidazol-2-yl)benzyl)benzofuran-2-yl)methanone (4m)
From 0.150 g compound 3b (0.384 mmol, 1 eq), and 0.088 g amine (0.576 mmol, 1.5 eq), the compound 4m was obtained as pale yellow (0.127 g, 85%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 250–255 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.74 (s, 1H, NH), 11.90 (s, 1H, OH), 8.3 (d, 2H, J = 8.1 Hz, Ar–H), 8.00–7.76 (m, 4H, Ar–H), 7.68–7.69 (m, 4H, Ar–H), 7.65 (d, 3H, Ar–H), 4.12, (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.2 (C=O), 156.4, 155.0, 153.8 (N–C–N), 150.9 (C–OH), 149.2, 140.3 (C–NO2), 139.8, 138.2 (C–Cl), 137.6, 136.2, 132.9, 131.2 (3C), 130.0, 129.2 (2C), 126.0, 119.0, 118.8, 116.9 (2C), 116.1, 112.5, 112.0, 42.2 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3510, 3450, 2590, 1790, 1664, 1600 cm−1; MS (ESI+): m/z = 524.10 ([M+H]+); and HRMS: m/z calcd for C29H19ClN3O5 ([M+H]+) 524.10660, found 524.10604.
(4-Chlorophenyl)(5-(3-(6-fluoro-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)methanone (4n)
From 0.150 g compound 3b (0.384 mmol, 1 eq), and 0.072 g amine (0.576 mmol, 1.5 eq), the compound 4n was obtained as white solid (0.120 g, 80%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (80:20, v/v). m.p.: 240–254 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.02 (s, 1H, NH), 12.52 (s, 1H, Ar–OH, D2O exchangeable), 8.55 (d, 3H, J = 7.2 Hz, Ar–H), 7.80–7.46 (m, 7H, Ar–H), 7.45–6.85 (m, 4H, Ar–H), 4.00 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.2 (C=O), 156.9, 155.1, 150.9 (N–C–N), 150.3 (C–OH), 139.9, 138.0, 137.5 (2C), 134.6, 132.0, 131.0 (3C), 129.4 (2C), 126.0, 121.4, 119.9, 116.5 (2C), 116.8, 112.0, 109.5, 102.0, 42.0 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3460, 3423, 1735, 1655, 1587 cm−1; MS (ESI+): m/z = 463.21 ([M+H]+); and HRMS: m/z calcd for C29H19ClFN2O3 ([M+H]+) 463.19608, found 463.19642.
(4-Chlorophenyl)(5-(3-(5,6-dimethyl-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl) benzo furan-2-yl)methanone (4o)
From 0.200 g compound 3b (0.512 mmol, 1 eq), and 0.104 g amine (0.769 mmol, 1.5 eq) the compound 4o was obtained as brick red (0.15 g, 75%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (70:30, v/v). m.p.: 250–255 °C; 1H NMR (400 MHz, DMSO-d6): δ = 12.95 (s, 1H, NH), 10.81 (s, 1H, OH), 8.01–7.90 (m, 4H, Ar–H), 7.77–7.70 (m, 6H, Ar–H), 7.53–6.98 (m, 3H, Ar–H), 6.95 (s, 1H, Ar–H), 4.09 (s, 2H, CH2), 2.38 (s, 6H, 2CH3) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.5 (C=O), 157.0, 156.8, 153.0 (N–C–N), 151.6 (C–OH), 137.9 (C–Cl), 137.6 (2C), 136.0, 134.5, 132.8 (2C), 132.0, 131.1 (2C), 128.5 (2C), 127.0, 124.8, 120.0, 118.7, 116.3 (2C), 113.9 (2C), 112.6, 42.2 (–CH2–), 21.0 (2C) ppm; IR (KBr): \(\bar{\nu }\) = 3480, 3423, 1724, 1645, 1567 cm−1; MS (ESI+): m/z = 507.8 ([M+H]+); and HRMS: m/z calcd for C31H24ClN2O3 ([M+H]+) 507.86082, found 507.86020.
(5-(3-(6-Chloro-1H-benzo[d]imidazol-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(4-chlorophenyl)methanone (4p)
From 0.150 g compound 3b (0.384 mmol, 1 eq), and 0.081 g amine (0.576 mmol, 1.5 eq), the compound 4p was obtained as light red solid (0.112 g, 75%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 235–237 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.12 (s, 1H, NH), 12.00 (s, 1H, OH), 8.02 (d, 2H, J = 7.5 Hz, Ar–H), 7.66–7.00 (m, 10H, Ar–H), 7.00 (d, 2H, J = 7.25 Hz, Ar–H), 4.00 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.2 (C=O), 155.9, 154.1, 153.4, 151.4, 137.9, 137.6 (2C), 135.3, 132.8, 132.1 (3C), 131.0, 129.9 (2C), 128.8 (2C), 126.9, 122.9, 118.3, 117.2 (3C), 116.6, 112.6, 42.0 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3458, 3400, 2570, 1795, 1655, 1597 cm−1; MS (ESI+): m/z = 513.1 ([M+H]+); and HRMS: m/z calcd for C29H19Cl2N2O3 ([M+H]+) 513.16082, found 513.16020.
(5-(4-Hydroxy-3-(1H-naphtho[2,3-d]imidazol-2-yl)benzyl)benzofuran-2-yl)(phenyl)methanone (4q)
From 0.200 g compound 3a (0.561 mmol, 1 eq), and 0.133 g amine (0.842 mmol, 1.5 eq) the compound 4q was obtained as white solid (0.172 g, 86%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 255–260 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.21 (s, 1H, NH), 9.97 (s, 1H, OH), 8.23 (s, 1H, Ar–H), 8.11 (s, 2H, Ar–H), 8.08–7.96 (m, 2H, Ar–H), 7.79–7.58 (m, 5H, Ar–H), 7.52 (t, 3H, J = 6.78 Hz, Ar–H), 7.51 (t, 1H, J = 5.7 Hz, Ar–H), 7.42 (s, 1H, Ar–H), 7.35 (s, 1H, Ar–H), 7.04 (d, 1H, J = 8.2 Hz, Ar–H), 4.18 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.1 (C=O), 156.3, 154.0, 152.9 (N–C–N), 151.5 (C–OH), 141.7 (2C), 138.2, 137.1, 136.7, 132.7, 131.9, 129.1, 128.6 (2C), 127.5 (2C), 127.0 (2C), 126.1, 122.9 (2C), 119.4, 118.6, 117.2, 117.0, 112.9 (2C), 112.2, 42.1 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3420, 2450, 1724, 1645,1547 cm−1; MS (ESI+): m/z = 495.23 ([M+H]+); and HRMS: m/z calcd for C33H23N2O3 ([M+H]+) 495.17081, found 495.17032.
(5-(4-Hydroxy-3-(1H-imidazo[4,5-b]pyridin-2-yl)benzyl)benzofuran-2-yl)(phenyl)methanone (4r)
From 0.150 g compound 3a (0.421 mmol, 1 eq), and 0.068 g amine (0.632 mmol, 1.5 eq), the compound 4r was obtained as white solid (0.120 g, 80%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 240–245 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.84 (s, 1H, NH), 12.83 (s, 1H, OH), 8.18–7.95 (m, 4H, Ar–H), 7.81–7.62 (m, 4H, Ar–H), 7.65-7.57 (t, 2H, Ar–H), 7.52 (d, 1H, J = 8.7 Hz, Ar–H), 7.32 (s, 2H, Ar–H), 7.01 (t, 1H, J = 8.2 Hz, Ar–H), 4.09 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.3 (C=O), 157.9, 153.2 (C–OH), 154.3, 151.4, 150.5, 144.5, 137.8, 136.9, 136.7, 135.3, 131.0, 130.3, 129.7, 129.7 (2C), 127.9 (2C), 126.9, 123.1, 121.8, 118.4, 117.7, 116.9 (2C), 112.2 (2C), 44.3 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3450, 3420, 1725, 1645, 1557 cm−1; MS (ESI+): m/z = 446.19 ([M+H]+); and HRMS: m/z calcd for C28H20N3O3 ([M+H]+) 446.11531, found 446.11570.
(5-(3-(5-Bromo-1H-imidazo[4,5-b]pyridin-2yl)4hydroxybenzyl)benzofuran-2-yl)(phenyl)methanone (4s)
From 0.180 g compound 3a (0.505 mmol, 1 eq), and 0.141 g amine (0.758 mmol, 1.5 eq), the compound 4s was obtained as yellow solid (0.140 g, 78%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 230–235 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.22 (s, 1H, NH), 12.58 (s, 1H, OH), 8.05 (s, 3H, Ar–H), 7.80–7.38 (m, 8H, Ar–H), 7.28 (s, 1H, Ar–H), 7.12 (d, 1H, Ar–H), 7.01 (s, 1H, Ar–H), 4.04 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 183.3 (C=O), 156.1, 154.0, 153.4, 151.6, 137.4, 136.7, 134.5, 134.1, 132.9, 132.2, 131.9, 130.0, 129.8 (2C), 129.0 (2C), 128.6 (2C), 126.4, 122.9, 121.7, 117.3, 116.9, 112.1, 42.3 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3580, 3423, 2650, 1730, 1651, 1554 cm−1; MS (ESI+): m/z = 423.99 ([M+H]+); and HRMS: m/z calcd for C28H19BrN3O3 ([M+H]+) 423.72551, found 423.72571.
(4-Chlorophenyl)(5-(4-hydroxy-3-(3H-imidazo[4,5-b]pyridin-2-yl)benzyl)benzofuran-2-yl)methanone (4t)
From 0.200 g compound 3b (0.512 mmol, 1 eq), and 0.083 g amine (0.769 mmol, 1.5 eq), the compound 4t was obtained as white solid (0.160 g, 80%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 240–245 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.85 (s, 1H, NH), 12.80 (s, 1H, Ar–OH, D2O exchangeable), 8.40 (m, 1H, Ar–H), 8.20–8.00 (m, 4H, Ar–H), 7.85–7.67 (m, 3H, Ar–H), 7.40–7.20 (d, 3H, J = 8.6 Hz, Ar–H), 7.38 (m, 2H, Ar–H), 4.05 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.2 (C=O), 159.2, 154.1, 153.1 (C–OH), 151.4, 150.5, 144.3 (C=N), 137.9, 137.6, 136.7, 135.3, 131.0, 130.9, 129.9, 129.5 (2C), 128.3 (2C), 126.9, 122.9, 122.0, 118.5, 117.3, 117.2 (2C), 112.2, 44.0 (–CH2–) ppm; IR (KBr): \(\bar{\nu }\) = 3450, 3425,1725, 1645, 1557 cm−1; MS (ESI+): m/z = 480.1 ([M+H]+); and HRMS: m/z calcd for C28H19ClN3O3 ([M+H]+) 480.09541, found 480.09581.
(5-(3-(5-Bromo-3H-imidazo[4,5-b]pyridin-2-yl)-4-hydroxybenzyl)benzofuran-2-yl)(4-chloro phenyl)methanone (4u)
From 0.250 g compound 3b (0.641 mmol, 1 eq), and 0.178 g amine (0.961 mmol, 1.5 eq), the compound 4u was obtained as light brown solid (0.195 g, 78%) after purified using chromatography on a silica gel column with petroleum ether/ethyl acetate (90:10, v/v). m.p.: 230–235 °C; 1H NMR (400 MHz, DMSO-d6): δ = 13.29 (s, 1H, NH), 12.35 (s, 1H, OH), 8.03 (s, 4H, Ar–H), 7.83–7.63 (m, 5H, Ar–H), 7.43 (t, 2H, Ar–H), 7.33 (s, 1H, Ar–H), 7.02 (d, 1H, J = 6.5, Ar–H), 4.04 (s, 2H, CH2) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 182.1 (C=O), 159.1, 155.4, 153.1, 151.6, 142.5, 140.1, 137.9, 134.5, 133.9, 132.9, 132.6, 131.9 (2C), 129.1 (2C), 129.8 (2C), 128.7 (2C), 126.9, 122.9, 119.4, 117.4, 117.3, 117.0, 112.9, 42.6 (–CH–) ppm; IR (KBr): \(\bar{\nu }\) = 3580, 3435, 2650, 1730, 1651, 1554 cm−1; MS (ESI+): m/z = 557.0 ([M+H]+); and HRMS: m/z calcd for C28H18BrClN3O3 ([M+H]+) 557.02551, found 557.02621.
In vitro antimicrobial assay
Antimicrobial activity was evaluated using agar well diffusion method. The activity was determined by measuring the diameter of the inhibition zone (in mm). Samples of the tested compounds (50 μL, 1 mg/mL concentration) were loaded into the wells on the plates. All solutions were prepared in DMSO and pure DMSO was loaded as control. The plates were kept for incubation at 35 °C for 1–5 days and then were examined for the formation of inhibition zone. Each inhibition zone was measured three times to get an average value. The test was performed three times for each bacterium culture [26,27,28].
Minimal inhibitory concentration (MIC) measurement
The microorganism’s susceptibility tests in nutrient and potato dextrose broths were used for the determination of MIC. Stock 1000 μg/mL solutions of the tested compounds, ciprofloxacin and nystatin were prepared in DMSO followed by dilutions to 250–25 μg/mL concentrations. Inoculated microorganism suspensions were incubated at 37 °C for 1–5 days for MIC determination. The microorganism suspensions were inoculated into the concentrations of corresponding compounds and control experiments and listed in Tables 1 and 2 respectively.
Evaluation of cell cytotoxicity
Hela, Supt1 cancer cell lines were used to evaluate the impact on cell viability of each compound. Hela cells were maintained in DMEM, Supt1 cells in RPMI, all the mediums were supplemented with 10% fetal bovine serum (FBS) cells were maintained in keratinocyte serum free media with 0.1 ng/mL human recombinant EGF, 0.05 mg/mL bovine pituitary extract and additional CaCl2 44.1 mg/mL (final concentration 0.4 mM), 2 mM l-glutamine at 37 °C under a 5% CO2 atmosphere. For each cell line, 70% confluent cell culture flask was trypsinized and were seeded cells in a 96-well plate at a density of 5000 cells by well in the appropriate complete media; These cells were treated with increasing concentrations of drugs, and incubated for 24 h. The cells were washed with media and resuspended in new medium. To this, 20 mL of 5 mg/mL MTT (Sigma-Aldrich) was added and incubated for 4f. The medium was removed from cells, and dissolved in DMSO (DMSO 0.1% in phosphate saline buffer) and read in an ELISA micro plate reader at 570 nm; 48 h after treatment, viability was accessed by MTT assay.