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Structure-Activity Relationship of New Anti-Hepatitis C Virus Agents: Heterobicycle-Coumarin Conjugates Johan Neyts,*,† Erik De Clercq,† Raghunath Singha,‡ Yung Hsiung Chang,‡ Asish R. Das,‡ Subhasish K. Chakraborty,‡ Shih Ching Hong,‡ Shwu-Chen Tsay,‡ Ming-Hua Hsu,‡ and Jih Ru Hwu*,‡,§ Rega Institute for Medical Research, Katholieke UniVersiteit LeuVen, Minderbroedersstraat 10, B-3000 LeuVen, Belgium, Department of Chemistry, National Tsing Hua UniVersity, Hsinchu, Taiwan 30013, R.O.C., Department of Chemistry, National Central UniVersity, Jhongli City, Taiwan 32001, R.O.C. ReceiVed July 22, 2008
For establishment of the structure-activity relationship, 19 heterobicycle-coumarin conjugated compounds with the -SCH2- linker were synthesized and found to possess significant antiviral activities. Prominent examples included imidazopyridine-coumarin 12c, purine-coumarin 12d, and benzoxazole-coumarin 14c, which inhibited HCV replication at an EC50 of 6.8, 2.0, and 12 µM, respectively. The heteroatoms in bicycles and the substituent effect on coumarin played essential roles. Scheme 1. Synthesis of Benzimidazole Derivatives
Introduction The benzimidazole moiety exists in many biologically active natural products and synthetic compounds.1 Some of them show clinical value toward breast cancer,2 leukemia,3 tumor cells,4 etc. Some possess potent antiviral activities.5 Beaulieu and coworkers6 synthesized a series of non-nucleoside benzimidazoles that are conjugated with pyridines or furans. Those hybrids show important antihepatitis C virus (HCV) effects. Hashimoto et al.7 also reported 2-arylbenzimidazole-5-carboxylic acids that possess inhibitory activity against HCV NS5B RNA polymerase. Recently, our laboratory found that the benzimidazole moiety conjugated with a coumarin moiety with a methylenethio linker exhibited potent inhibitory effects on HCV.8 We therefore planned to design and synthesize a series of analogues by incorporating heteroatoms into the benzimidazole moiety. Also, modification of the coumarin moiety and attachment onto it with different functional groups was performed. It was our goal to establish the structure-activity relationship (SAR) for antiviral activity on the basis of this new compound library. Hepatitis C virus is a small enveloped RNA virus that belongs to the family Flaviviridae and the genus Hepaci-Virus.9Currently, about 170 million people around the world suffer from chronic HCV infection, which causes a progressive liver disease.10 Between 40% and 85% of patients do not clear the virus, and most of these develop chronic hepatitis C. Use of interferon R-2 alone or its combination with ribavirin is the only treatment option available nowadays.11,12 Unfortunately, sustained response is observed in only about 40% of the patients; meanwhile, the treatment is associated with serious adverse effects. Herein we report our approaches on the synthesis of various conjugated compounds in the family of benzimidazole, imidazopyridine, purine, benzoxazole, and benzothiazole. Their antiviral activities were evaluated and a structure-activity relationship was established. Synthesis of Benzimidazole Derivatives 3 and 5a-d. To understand the essential role of coumarin moiety in conjugated * To whom correspondence should be addressed. For J.R.H: phone, 88635-725813; fax, 886-35-721594; E-mail,
[email protected]. For J.N.: phone, 0032-16-337353; fax, 0032-16-337340; E-mail, johan.neyts@ rega.kuleuven.be. † Katholieke Universiteit Leuven. ‡ National Tsing Hua University. § National Central University.
compounds with antiviral activities, we replaced the coumarin moiety with a naphthalene, benzene, or pyridine moiety. Thus we treated thiones 113 with 2-(chloromethyl)naphthalene (2), benzyl chloride (4a), or 4-(chloromethyl)pyridine (4b) in the presence of 35% NH4OH in water and acetonitrile (see Scheme 1). Upon workup and purification by chromatography, benzimidazole analogues 3 and 5a-d were produced individually in 70-77% yields. Furthermore, we followed a reported procedure8 to silylate 2-mercaptobenzimidazole (1a) with N,O-bistrimethylsilylactamide (BTSA). The intermediate was then coupled with Operacetyl-pyranose 6 in the presence of Me3SiOTf at 80 °C (Scheme 2). The resultant 2-thiobenzimidazole 78 was alkylated with p-nitrobenzyl bromide (8) at room temperature to give N-(glucopyranosyl)benzimidazole 9. Syntheses of Imidazopyridine and Purine Derivatives 12. Incorporation of heteroatoms in the benzimidazole nucleus would provide valuable information on establishment of an SAR. Consequently, we coupled imidazopyridine-2-thione (10a)13 with 3-(chloromethyl)coumarins 1114 to give the desired imidazopyridine-coumarin conjugates 12a-c (Scheme 3). Under the same conditions, purine-8-thione (10b) was successfully converted to the purine-coumarin conjugates 12d and 12e.
10.1021/jm801240d CCC: $40.75 2009 American Chemical Society Published on Web 02/04/2009
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Scheme 2. A Synthetic Pathway to Generate an N-(Glucopyranosyl)benzimidazole
Scheme 3. Synthesis of Imidazopyridine- and Purine-Coumarin Conjugates
The overall yields of 12a-e ranged from 65% to 83% and their purity was >98%, as determined by HPLC, 1H NMR, 13C NMR, and HRMS. We confirmed the structures of conjugates 12 on the basis of their spectroscopic characteristics. For example, the conjugate 12c possessed an odd mass number 387. Given the nitrogen rule,15 it must contain an odd number of nitrogen atoms. Its IR spectrum showed one strong absorption band at 1720 cm-1, which was attributed to the carbonyl stretching vibration of the coumarin moiety. Its 13C NMR spectrum exhibited a resonance at 30.31 ppm for the SCH2 carbon. On the other hand, the two characteristic singlets occurred at 8.75 and 8.91 ppm in the 1H NMR spectrum of conjugate 12e. These peaks came from the protons in the purine nucleus. The OCH3 protons attached to the coumarin moiety showed resonance at 3.80 ppm; the two protons in the SCH2 spacer appeared as a singlet at 4.48 ppm. Synthesis of Benzoxazole and Benzothiazole Derivatives 14. We allowed thiones 1313 to react with coumarins 11 and 35% aqueous NH4OH in acetonitrile (see Scheme 4). Five new compounds in the family of benzoxazole-coumarin conjugate (i.e., 14a-c) and benzothiazole-coumarin conjugate (i.e., 14d and 14e) were produced in 69-89% yields. Thus one of the two nitrogen atoms in the imidazole nucleus of benzimidazolecoumarin conjugates was successfully replaced by an oxygen or a sulfur atom. Synthesis of Benzimidazole-Coumarin Nucleosides 17. Xu et al.16 isolated O-galloyl-β-D-glucoses from traditional Chinese medicine Galla Chinese. Three glucose esters in this family are identified as inhibitors of hepatitis C virus NS3 protease.
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Scheme 4. Synthesis of Benzoxazole- and Benzothiazole-Coumarin Conjugates
Scheme 5. A Synthetic Pathway to Generate Benzimidazole-Coumarin Nucleoside
Consequently, we planned to attach a pyranose moiety onto 2-thiobenzimidazoles 1a,b as shown in Scheme 5. Glycosylation8 of 1a,b with O-peracetyl-2-deoxy-β-D-glucose (15) in the presence of Me3SiOTf generated intermediates 16a,b, respectively. The thione moiety therein allowed these compounds to be coupled with coumarins 11 to produce the desired target compounds 17a-c with β configuration in 75-92% yields. Their structures were confirmed by spectroscopic methods. For example, the mass spectrum of 17c in the positive ion mode under electrospray ionization method exhibited two peaks at 659.06 and 661.06 for the species [M + H]+, which indicates the molecular formula to be C29H27BrN2O9S. The three moieties joined together included benzimidazole, coumarin, and dexoyglucopyranose. The -NdC(-N)(-S) carbon resonated at the
1488 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 5 Table 1. Inhibitory Effects of Conjugated Compounds on HCV HCV compdsa 3 5a 5b 5c 5d 7 9 12a 12b 12c 12d 12e 14a 14b 14c 14d 14e 17a 17b 17c 18ae 18be 19e
CC50,µMb 56 197 107 196 199 104 83 95 30 128 109 94 45 18 131 153 40 11 26 16 90 27 74
EC50, µMc 76 197 100 184 199 104 63 59 11 6.8 2.0 20 12 19 12 80 29 1.8 12 4.1 27 10 15
SId 0.73 1.0 1.1 1.1 1.0 1.0 1.3 1.6 2.8 19 54 4.8 3.9 0.96 11 1.9 1.4 6.4 2.2 4.0 3.4 2.8 4.9
a Interferon R-2b was used as a (positive) reference compound at 10000 units/well and reduced the signal in the viral RNA (luciferase) assay to background levels without any cytotoxic activity. b Minimum cytotoxic concentration required to cause a microscopically detectable alteration of normal cell morphology. c Minimum inhibitory concentration required to reduce virus-induced cytopathogenicity by 50%. d Selectivity index (ratio of CC50 to EC50). e Synthesis reported in the ref 8.
150.20 ppm in the 13C NMR spectrum. On the other hand, the two diastereotopic SCH2 protons appeared at 4.56 and 4.48 ppm as two doublets with J ) 13.6 Hz in its 1H NMR spectrum. Of importance is the glycosidic proton, which resonated at the 5.71 ppm as a doublet of doublet with J ) 8.4 and 1.6 Hz. Often R anomers possess two small coupling constants (e.g., 3.6 and 1.1 Hz)17 and β anomers possess one big (∼9.5 Hz) and one small (∼2.0 Hz) coupling constant.18 Accordingly we assign compound 17c as a β-D-pyranoside. Our assignment is also on the basis of related works reported by Nord,19 Mulligan,20 and co-workers. They found that coupling of either R or β acetylated/ benzoylated 2-deoxy-D-hexopyranoses with silylated bases in the presence of Me3SiOTf affords the β anomers. Antiviral Evaluation in the HCV Genotype 1b Subgenomic Replicon. All compounds were evaluated in the HCV subgenomic replicon system in Huh 5-2 cells, which were kindly provided by Prof. R. Bartenschlager, University of Heidelberg, Germany.21 The antiviral assays and cytostatic determination assays have been described in detail before.22 Three out of the 19 newly synthesized conjugated compounds were found to inhibit HCV subgenomic replicon replication in the Huh 5-2 cell line with potency. The 50% inhibitory concentrations for virus replication (EC50), host cell growth (CC50), and the selectivity index (SI ) CC50/EC50), are shown inTable1.Imidazopyridine-coumarinconjugate12c,purine-coumarin conjugate 12d, and benzoxazole-coumarin conjugate 14c inhibited HCV replication at EC50 values of 6.8, 2.0, and 12 µM, respectively. Structure-Activity Relationship. We used the -SCH2linker to connect two heterocyclic nuclei for the formation of various conjugated compounds. The sulfur atom was attached to a benzimidazole, imidazopyridine, purine, benzoxazole, or benzothiazole moiety. The methylene terminal was attached to a substituted arene, pyridine, or coumarin. We deduce the
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following SAR by scrutinizing their EC50 and CC50 values shown in Table 1. (1) Attachment of an imidazopyridine (e.g., 12c) or benzoxazole (e.g., 14c) nucleus to the thio terminal of the coumarin conjugates may offer a convenient approach to obtain compounds with appealing anti-HCV activity (EC50 6.8-12 µM) and significant selectivity index values (11-19). (2) Replacement of a carbon atom with a nitrogen atom in the imidazopyridine nucleus (i.e., purine) of the conjugated coumarins increased the HCV inhibition by a factor of 29-fold (cf. 12a vs 12d). (3) Attachment of the coumarin moiety to the methylene terminal is key to gain biological activities for the conjugated heterobicyclic compounds. This essential moiety cannot be replaced by an aryl (e.g., 3) or pyridyl group (e.g., 5a-d). (4) Placement of a Br- substituent onto the coumarin nucleus of its imidazopyridine conjugate (cf. 12a vs 12c) enhanced the HCV inhibition by a factor of 8.7-fold. (5) Placement of a Br- substituent onto the coumarin nucleus of its benzoxazole conjugate (cf. 14a vs 14c) reduced the cytotoxicity by a factor of 2.9-fold. (6) Placement of an MeO- substituent on the coumarin nucleus of its imidazopyridine conjugate (cf. 12a vs 12b) improved the antiviral activity by a factor of 5.4-fold. (7) Incorporation of an arene moiety to benzimidazoleperacetyl glucose conjugate (cf. 7 vs 9) made limited contribution to its HCV inhibition. (8) Incorporation of a peracetyl 2-deoxy-β-D-glucose moiety onto the benzimidazole-coumarin conjugates increased both the HCV inhibition (8.2-fold) and cytotoxicity (cf. 17a vs 19). Conclusion The -SCH2- linker was used to connect a heterobicycle with various aromatic rings by chemically synthetic methods to form hybrid compounds for antiviral bioassays. The heterobicycles included benzimidazole, imidazopyridine, purine, benzoxazole, and benzothiazole; the aromatic rings included naphthalene, benzene, pyridine, and coumarin with substituents. In this new compound library, three heterobicycle-coumarin conjugates exhibited low micromolar EC50s against HCV. A purine-coumarin conjugate 12d exhibited potent anti-HCV activity at an EC50 value of 2.0 µM. More important is the establishment of a structure-activity relationship, which discloses the essential scaffold including heterobicycles and the substituents on coumarin. Experimental Section Standard Procedure for the Preparation of Conjugated Compounds. To a solution containing a thione (1.0 equiv) in acetonitrile (15 mL) was added aqueous ammonium hydroxide (35%, 0.52 mL). After the solution was stirred at room temperature for 30 min, an organic chloride (1.0 equiv) in acetonitrile (2.0 mL) was added. It was stirred for another 18 h to give precipitates, which were collected by vacuum filtration. The residues were purified by use of column chromatography packed with silica gel and eluented with a mixture of EtOAc and hexanes. The resultant solids were recrystallized with a mixture of EtOAc and hexanes to give the desired products with purity >98%, determined by HPLC, 1H NMR, 13 C NMR, and HRMS. 2-(6′-Bromocoumarin-3′-yl)methylthio-1H-imidazo[4,5-b]pyridine (12c). The Standard Procedure was followed by use of imidazopyridine-2-thione13 (10a, 76 mg, 0.50 mmol, 1.0 equiv) and 6-bromo-3-(chloromethyl)coumarin14 (11c, 138 mg, 0.503, 1.0 equiv). After workup and purification, the solids were recrystallized with 40% EtOAc in hexanes to give 12c (161 mg, 0.416 mmol) in 83% yield as white solids; mp (recrystallized from EtOAc)
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332-333 °C. 1H NMR (DMSO-d6, 400 MHz) δ 8.20 (d, J ) 4.0 Hz, 1 H, ArH), 8.16 (s, 1 H, ArH), 7.86 (s, 1 H, ArH), 7.74 (d, J ) 2.8 Hz, 1 H, ArH), 7.68 (d, J ) 2.4 Hz, 1 H, ArH), 7.37 (d, J ) 4.8 Hz, 1 H, ArH), 7.17-7.14 (m, 1 H, ArH), 4.43 (s, 2 H, SCH2). 13C NMR (DMSO-d6, 100 MHz) δ 160.45, 152.59, 143.11, 141.72, 140.31, 135.35, 134.76, 131.44, 131.12, 126.34, 121.39, 119.04, 118.14, 117.5, 116.08, 31.08. IR (KBr) 3157 (br, N-H), 1720 (s, CdO), 1597 (m), 1481 (m), 1419 (m) cm-1. MS (ESI) m/z (M + H)+ 388.0, 340.0. HRMS m/z calcd for C16H10BrN3O2S, 386.9677; found, 386.9674. Anal. (C16H10BrN3O2S) C, H, N. 8-[(Coumarin-3′-yl)methylthio]purine (12d). The Standard Procedure was followed by use of purine-8-thione13 (10b, 53 mg, 0.35 mmol, 1.0 equiv) and 3-(chloromethyl)coumarin14 (11a, 69 mg, 0.36 mmol, 1.0 equiv). After workup and purification, the solids were recrystallized with 40% EtOAc in hexanes to give 12d (80 mg, 0.26 mmol) in 74% yield as light-brown solids; mp (recrystallized from EtOAc) 151-152 °C. 1H NMR (DMSO-d6, 400 MHz) δ 8.78 (s, 1 H, ArH), 8.40 (s, 1 H, ArH), 8.19 (s, 1 H, ArH), 7.69-7.65 (m, 2 H, 2 × ArH), 7.33-7.28 (m, 2 H, 2 × ArH), 4.44 (s, 2 H, SCH2). 13C NMR (DMSO-d6, 100 MHz) δ 160.23, 156.47, 152.90, 152.38, 151,05, 142.00, 141.30, 134.84, 131.87, 128.49, 124.74, 124.03, 118.78, 116.10, 30.50. IR (KBr) 3139 (br, N-H), 1712 (s, CdO), 1612 (m), 1404 (s) cm-1. MS (ESI) m/z (M + H)+ 311.0. HRMS m/z calcd for C15H10N4O2S, 310.0524; found, 310.0527. Anal. (C15H10N4O2S) C, H, N. 8-[(8′-Methoxycoumarinyl)methylthio]purine (12e). The Standard Procedure was followed by use of purine-8-thione13 (10b, 50 mg, 0.33 mmol, 1.0 equiv) and 3-chloromethyl-8-methoxycoumarin14 (11b, 77 mg, 0.34 mmol, 1.0 equiv). After workup and purification, the solids were recrystallized with 50% EtOAc in hexanes to give 12e (84 mg, 0.25 mmol) in 75% yield as lightbrown solids; mp (recrystallized from EtOAc) 153-154 °C. 1H NMR (DMSO-d6, 400 MHz) δ 8.91 (s, 1 H, ArH), 8.75 (s, 1 H, ArH), 8.16 (s, 1 H, ArH), 7.26-7.19 (m, 4 H, 4 × ArH), 4.46 (s, 2 H, SCH2), 3.80 (s, 3 H, OCH3). 13C NMR (DMSO-d6, 100 MHz) δ 160.62, 156.49, 151.90, 151.71, 147,04, 142.87, 142.19, 141.90, 134.85, 125.36, 124.86, 120.25, 120.01, 114.77, 56.75, 31.15. IR (KBr) 3132 (br, N-H), 1714 (s, CdO), 1608 (m), 1406 (m) cm-1. MS (ESI) m/z (M + H)+ 341.0. HRMS m/z calcd for C16H12N4O3S, 340.0630; found, 340.0632. Anal. (C16H12N4O3S) C, H, N. 2-(6′-Bromocoumarin-1′-yl)methylthio-1-(3′′,4′′,6′′-tri-O-acetyl2′′-deoxy-β-D-glucopyranos-1′′-yl)benzimidazole (17c). The Standard Procedure was followed by use of benzimidazole-2-thione8 (16a, 80 mg, 0.19 mmol, 1.0 equiv) and 6-bromo-3-(chloromethyl)coumarin14 (11c, 55 mg, 0.20 mmol, 1.0 equiv). After workup and purification, the solids were recrystallized with 30% EtOAc in hexanes to give 17c (98 mg, 0.15 mmol) in 79% yield as white solids; mp (recrystallized from EtOAc) 198-199 °C. 1H NMR (CDCl3, 400 MHz) δ 7.98 (s, 1 H, ArH), 7.64 (d, J ) 7.6 Hz, 1 H, ArH), 7.52-7.47 (m, 2 H, 2 × ArH), 7.24-7.18 (m, 4 H, 4 × ArH), 5.71 (dd, J ) 8.4 Hz, J ) 1.6 Hz, 1 H, H-1′), 5.21-5.16 (m, 2 H, H-3′, H-4′), 4.56 (d, J ) 13.6 Hz, SCH2), 4.48 (d, J ) 13.6 Hz, SCH2), 4.23-4.17 (m, 2 H, H-6′), 3.87-3.83 (m, 1 H, H-5′), 2.43-2.38 (m, 2 H, H-2′), 2.03 (s, 3 H, CH3), 2.02 (s, 3 H, CH3), 1.99 (s, 3 H, CH3). 13C NMR (CDCl3, 100 MHz) δ 170.51 (CdO), 169.93 (CdO), 169.33 (CdO), 160.46 (CdO), 152.27, 150.20, 143.58, 140.24, 134.52, 134.13, 130.18, 125.99, 125.71, 122.62, 122.48, 120.63, 118.60, 116.98, 111.11, 81.21 (C1′), 74.65 (C5′), 70.46 (C4′), 67.26 (C3′), 61.80 (C6′), 34.41 (SCH2), 31.52 (C2′), 20.97 (CH3), 20.89 (CH3), 20.66 (CH3). IR (KBr) 1753 (s, CdO), 1726 (s, CdO), 1442 (m), 1368 (m), 1249 (s), 1212 (m), 1059 (m), 741 (m) cm-1. MS (ESI) m/z (M + H)+ 659.06, 661.06. HRMS m/z calcd for C29H27BrN2O9S, 658.0621; found, 658.0626. Anal. (C29H27BrN2O9S) C, H, N.
Acknowledgment. For financial support, we thank the National Science Council and Ministry of Education of R.O.C. The work in Leuven was supported by the Fonds voor Wetenschappelijk Onderzoek Vlaanderen (G.0267.03) and by the VIRGIL European Network of Excellence on Antiviral Drug
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Resistance grant (LSHM-CT-2004-503359) from the Priority 1 “Life Sciences, Genomics and Biotechnology for Health” program in the 6th framework program of the EU. We thank Mrs. Katrien Geerts for fine experimental assistance and Wellbeing Biochemical Corporation for its support on instrumentation. Supporting Information Available: 1H NMR, 13C NMR, and HRMS data for all the compounds disclosed. This material is available free of charge via the Internet at http://pubs.acs.org.
References (1) For recent reviews, see: (a) Boiani, M.; Gonza´lez, M. Imidazole and benzimidazole derivatives as chemotherapeutic agents. Mini ReV. Med. Chem. 2005, 5, 409. (b) El-On, J. Benzimidazole treatment of cystic echinococcosis. Acta Trop. 2003, 85, 243–252. (2) (a) For recent reports, see: Andrzejewska, M.; Ye´pez-Mulia, L.; Cedillo-Rivera, R.; Tapia, A.; Vilpo, L.; Vilpo, J.; Kazimierczuk, Z. Synthesis, antiprotozoal and anticancer activity of substituted 2-trifluoromethyl- and 2-pentafluoroethylbenzimidazoles. Eur. J. Med. Chem. 2002, 37, 973–978. (b) Gumus, F.; Algul, O.; Eren, G.; Erolu, H.; Diril, N.; Gur, S.; Ozkul., A. Synthesis, cytotoxic activity on MCF-7 cell line and mutagenic activity of platinum(II) complexes with 2-substituted benzimidazole ligands. Eur. J. Med. Chem. 2003, 38, 473–480. (c) Kamal, A.; Ramulu, P.; Srinivas, O.; Ramesh, G.; Kumar, P. P. Synthesis of C8-linked pyrrolo[2,1-c][1,4]benzodiazepinebenzimidazole conjugates with remarkable DNA-binding affinity. Bioorg. Med. Chem. Lett. 2004, 14, 4791–4794. (d) Chauhan, P. M. S.; Martins, C. J. A.; Horwell, D. C. Synthesis of novel heterocycles as anticancer agents. Bioorg. Med. Chem. 2005, 13, 3513–3518. (3) For recent representative works, see: (a) Garuti, L.; Roberti, M.; Malagoli, M.; Rossi, T.; Castelli, M. Synthesis and antiproliferative activity of some benzimidazole-4,7-dione derivatives. Bioorg. Med. Chem. Lett. 2000, 10, 2193–2195. (b) Demirayak, S.; Mohsen, U. A.; Karaburun, A. C. Synthesis and anticancer and anti-HIV testing of some pyrazino[1,2-a]benzimidazole derivatives. Eur. J. Med. Chem. 2002, 37, 255–260. (4) For recent reports, see: (a) Lukevics, E.; Arsenyan, P.; Shestakova, I.; Domracheva, I.; Nesterova, A.; Pudova, O. Synthesis and antitumour activity of trimethylsilylpropyl substituted benzimidazoles. Eur. J. Med. Chem. 2001, 36, 507-515; (b) Handratta, V. D.; Vasaitis, T. S.; Njar, V. C. O.; Gediya, L. K.; Kataria, R.; Chopra, P., Jr.; Farquhar, R.; Guo, Z.; Qiu, Y.; Brodie, A. M. H. Novel C-17-heteroaryl steroidal CYP17 inhibitors/antiandrogens: synthesis, in vitro biological activity, pharmacokinetics, and antitumor activity in the LAPC4 human prostate cancer xenograft model. J. Med. Chem. 2005, 48, 2972–2984. (5) For related reports, see: (a) Komazin, G.; Ptak, R. G.; Emmer, B. T.; Townsend, L. B.; Drach, J. C. Resistance of human cytomegalovirus to D- and L-Ribosyl benzimidazoles as a tool to identify potential targets for antiviral drugs. Nucleosides, Nucleotides Nucleic Acids 2003, 22, 1725–1727. (b) Yu, K.-L.; Civiello, R. L.; Combrink, K. D.; Gulgeze, H. B.; Sin, N.; Wang, X.; Meanwell, N.; Venables, Brian, L.; Zhang, Y.; Pearce, B. C.; Yin, Z.; Thuring, J. W. Heterocyclic substituted 2-methyl-benzimidazole antiviral agents. U. S. Patent 0 099 208, 2002; (c) Bretner, M.; Baier, A.; Kopanska, K.; Najda, A.; Schoof, A.; Reinholz, M.; Lipniacki, A.; Piasek, A.; Kulikowsi, T.; Borowski, P. Synthesis and biological activity of 1H-benzotriazole and 1Hbenzimidazole analoguessinhibitors of the NTPase/helicase of HCV and of some related Flaviviridae. AntiViral Chem. Chemother. 2005, 16, 315–326. (6) For their recent works, see: (a) Beaulieu, P. L.; Bousquet, Y.; Gauthier, J.; Gillard, J.; Marquis, M.; McKercher, G.; Pellerein, C.; Valois, S.; Kukolj, G. Non-nucleoside benzimidazole-based allosteric inhibitors of the hepatitis C virus NS5B polymerase: inhibition of subgenomic hepatitis C virus RNA replicons in Huh-7 Cells. J. Med. Chem. 2004, 47, 6884–6892. (b) McKercher, G.; Beaulieu, P. L.; Lamarre, D.; LaPlante, S.; Lefebvre, S.; Pellerin, C.; Thauvette, L.; Kukolj, G. Specific inhibitors of HCV polymerase identified using an NS5B with lower affinity for template/primer substrate. Nucleic Acids Res. 2004, 32, 422–431. (c) Beaulieu, P. L.; Bo¨s, M.; Bousquet, Y.; DeRoy, P.; Fazal, G.; Gauthier, J.; Gillard, J.; Goulet, S.; McKercher, G.; Poupart, M.-A.; Valois, S.; Kukolj, G. Non-nucleoside inhibitors of the hepatitis C virus NS5B polymerase: discovery of benzimidazole 5-carboxylic amide derivatives with low-nanomolar potency. Bioorg. Med. Chem. Lett. 2004, 14, 967–971. (7) For their recent reports, see: (a) Hirashima, S.; Suzuki, T.; Ishida, T.; Noji, S.; Yata, S.; Ando, I.; Komatsu, M.; Ikeda, S.; Hashimoto, H. Benzimidazole derivatives bearing substituted biphenyls as hepatitis C virus NS5B RNA-dependent RNA polymerase inhibitors: structureactivity relationship studies and identification of a potent and highly selective inhibitor JTK-109. J. Med. Chem. 2006, 49, 4721–4736. (b) Ishida, T.; Suzuki, T.; Hirashima, S.; Mizutani, K.; Yoshida, A.; Ando,
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I.; Ikeda, S.; Adachi, T.; Hashimoto, H. Benzimidazole inhibitors of hepatitis C virus NS5B polymerase: identification of 2-[(4-diarylmethoxy)phenyl]-benzimidazole. Bioorg. Med. Chem. Lett. 2006, 16, 1859–1863. Hwu, J. R.; Singha, R.; Hong, S. C.; Chang, Y. H.; Das, A. R.; Vliegen, I.; DeClercq, E.; Neyts, J. Synthesis of new benzimidazole-coumarin conjugates as anti-hepatitis C virus agents. AntiViral Res. 2008, 77, 157–162. Hoofnagle, J. H. The course and outcome of hepatitis C. Hepatology 2002, 36, S21–S29. For recent reports, see: (a) Lauer, G. M.; Walker, B. D. Hepatitis C virus infection. N. Engl. J. Med. 2001, 345, 41–52. (b) Richter, S. S. Laboratory assays for diagnosis and management of hepatitis C virus infection. J. Clin. Microbiol. 2002, 40, 4407–4412. Zein, N. N. Etanercept as an adjuvant to interferon and ribavirin in treatment-naive patients with chronic hepatitis C virus infection: a phase 2 randomized, double-blind, placebo-controlled study. J. Hepatol. 2005, 42, 315–322. Manns, M. P.; McHutchison, J. G.; Gordon, S. C.; Rustgi, V. K.; Shiffman, M.; Reindollar, R.; Goodman, Z. D.; Koury, K.; Ling, M.H.; Albrecht, J. K. Peginterferon alfa-2b plus ribavirin compared with interferon alfa-2b plus ribavirin for initial treatment of chronic hepatitis C: a randomized trial. Lancet 2001, 358, 958–965. For the preparations of thiones, see: (a) Mavrova, A. T.; Denkova, P.; Tsenov, Y. A.; Anichina, K. K.; Vutchev, D. I. Synthesis and antitrichinellosis activity of some bis(benzimidazol-2-yl)amines. Bioorg. Med. Chem. 2007, 15, 6291–6297. (b) Wilde, R. G.; Billheimer, J. T.; Germain, S. J.; Gillies, P. J.; Higley, C. A.; Kezar, H. S., III; Maduskuie, T. P.; Shimshick, E. S.; Wexler, R. R. Acyl CoA: cholesterol acyltransferase (ACAT) inhibitors: ureas bearing heterocyclic groups bioisosteric for an imidazole. Bioorg. Med. Chem. Lett. 1995, 5, 167–172. (c) Van Allan, J. A.; Deacon, B. D. 2-Mercaptobenzimidazole. Org. Synth. 1963, 4, 569–570.
Brief Articles (14) Kaye, P. T.; Musa, M. A.; Nocanda, X. W. Efficient and chemoselective access to 3-(chloromethyl)coumarins via direct cyclisation of unprotected Baylis-Hillman adducts. Synthesis 2003, 531, 534. (15) Silverstein, R. M.; Webster, F. X.; Kiemle, D. J. Spectrometric Identification of Organic Compounds, 7th ed.; John Wiley: New York, 2005; p 14. (16) Duan, D.; Li, Z.; Luo, H.; Zhang, W.; Chen, L.; Xu, X. Antiviral compounds from traditional Chinese medicines Galla Chinese as inhibitors of HCV NS3 protease. Bioorg. Med. Chem. Lett. 2004, 14, 6041–6044. (17) Dang, H.-S.; Roberts, B. P.; Sekhon, J.; Smits, T. M. Deoxygenation of carbohydrates by thiol-catalysed radical-chain redox rearrangement of the derived benzylidene acetals. Org. Biomol. Chem. 2003, 1, 1330– 1341. (18) Lam, S. N.; Gervay-Hague, J. An effcient route to 2-deoxy-beta-Oaryl-D-glycosides via direct displacement of glycosyl iodides. Org. Lett. 2003, 5, 4219–4222. (19) Nord, L. D.; Dalley, N. K.; McKernan, P. A.; Robins, R. K. Synthesis, structure, and biological activity of certain 2-deoxy-beta-D-ribohexopyranosyl nucleosides and nucleotides. J. Med. Chem. 1987, 30, 1044–1054. (20) Khan, A. R.; Mulligan, K. X.; Redda, K. K.; Ollapally, A. P. Synthesis of 3′-azido-2′,3′- dideoxy-4′-ketonexopyranoid analogues as possible antiviral nucleosides. Synth. Commun. 2002, 32, 1023–1030. (21) Lohmann, V.; Korner, F.; Koch, J.; Herian, U.; Theilmann, L.; Bartenschlager, R. Replication of subgenomic hepatitis C virus RNAs in a hepatoma cell line. Science 1999, 285, 110–113. (22) Paeshuyse, J.; Kaul, A.; De Clercq, E.; Rosenwirth, B.; Dumont, J.M.; Scalfaro, P.; Bartenschlager, R.; Neyts, J. The non-immunosuppressive cyclosporin DEBIO-025 is a potent inhibitor of hepatitis C virus replication in vitro. Hepatology 2006, 43, 761–770.
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