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An alternative route to the arylvinyltriazole nucleosides
Accepted Manuscript An alternative route to the arylvinyltriazole nucleosides Mikhail V. Chudinov, Alexander N. Prutkov, Andrey V. Matveev, Lyubov E. Grebenkina, Irina D. Konstantinova, Yulia V. Berezovskaya PII: DOI: Reference:
S0960-894X(16)30570-4 http://dx.doi.org/10.1016/j.bmcl.2016.05.072 BMCL 23931
To appear in:
Bioorganic & Medicinal Chemistry Letters
Received Date: Revised Date: Accepted Date:
21 April 2016 23 May 2016 25 May 2016
Please cite this article as: Chudinov, M.V., Prutkov, A.N., Matveev, A.V., Grebenkina, L.E., Konstantinova, I.D., Berezovskaya, Y.V., An alternative route to the arylvinyltriazole nucleosides, Bioorganic & Medicinal Chemistry Letters (2016), doi: http://dx.doi.org/10.1016/j.bmcl.2016.05.072
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
An alternative route to the arylvinyltriazole nucleosides. Mikhail V. Chudinov a†, Alexander N. Prutkov a, Andrey V. Matveev a, Lyubov E. Grebenkina a, Irina D. Konstantinovab, Yulia V. Berezovskaya с a
Lomonosov Institute of Fine Chemical Tehnologies, Moscow Technological University, Vernadskogo Pr. 78, 119454, Russia. b Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, MiklukhoMaklaya St. 16/10, 117997 GSP, Moscow B-437, Russia. c Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region, 141700, Russia. † Corresponding author: [email protected] Abstract A new pathway to synthesis of arylvinyl ribavirin analogues is developed which makes it possible to obtain not only trans- but also cis-isomers at vinyl bond. By this route eight ribavirin 5-arylvinyl analogues are synthesized and their antiviral activity is evaluated.
In this article we focus on investigation of the structure-activity relationships for structure analogues of ribavirin (1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), an antiviral agent that has demonstrated efficacy in treating a wide range of viral diseases 1-2. Although several alternative mechanisms have been proposed by which ribavirin and its analogues may induce their antiviral activity3-5, there is still no consistent and comprehensive picture on this matter.
Figure 1. Anti-HCV nucleoside analogues: 1 - Ribavirine; 2-4 - the most active 5-aryl/alkylethynyl analogues6. A considerable antiviral and antitumour activity has been reported for ribavirin analogues bearing arylethynyl moieties at the 5th position of triazole ring 6-11. It was shown that replacing the triple bond from compound (2) (Fig. 1) with a flexible single bond led to the inactive analogues8. This was explained by the triple bond rigidity and therefore it indicates the existence of a correlation between structure of the moiety at the 5th position and the antiviral activity. Recently, Tang et al.12 offered the effective synthetic route to ribavirin 5-arylvinyl analogues bearing rigid double bond directly from the unprotected ribavirin using the oxidative Heck reaction. This approach allows one to obtain desired products with high yields but also has some disadvantages. Specifically, only trans-isomers can be obtained and the arylvinyl substituents variety is limited by starting styrene structures. We are particularly interested in the antiviral activity of 5-arylvinyl analogues and the structure-activity relationship for substituents at the 5th position of the triazole ring. While our new route to 5-arylvinyl ribavirin analogues gives desired products with lower general yields, it allows us to obtain not only trans- but also cis-isomers at vinyl bond; as a consequence this provides a wider molecular diversity including new 5-alkylvinyl ribavirin analogues. Thus, we are able to analyze the antiviral activity as a function of not only the substituent structure but also of the ethynyl linker double bond E/Z isomerism. The synthesis of arylvinyl ribavirin analogues was carried out via the Wittig reaction starting from the common precursor. To this end, ethyl 5-benzyloxymethyl-1H-1,2,4-triazole-3carboxylate (6), obtained by published method13-14, was glycosylated by D-ribose tetraacetate in the presence of bis(4-nitrophenyl) phosphate (Scheme 1). A mixture of 1- and 2-regioisomers (7) and (7а) was obtained in 5:1 ratio.
Scheme 1.
Synthesis of 5-benzyloxymethyl-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-[1,2,4]-triazole-3-
carboxylic acid ethyl ester (7). Reagents and condition: (a) EtOH, rt, 24 hr, 95% yield; (b) Py, refl, 5 hr, 59% yield; (c) 160◦C, 1 hr, 56% yield of (7). The nucleoside β-anomer (7) was separated by column chromatography on silica gel followed by debenzylation and subsequent oxidation to aldehyde (9) (Scheme 2). Then, the protected nucleosides (10a-g) were obtained by the reaction of the corresponding phosphonic salts 15. For the most part, isomeric ratio of products was obtained (approximately E:Z=1:1.25). As E- and Zisomers were separated they were converted to corresponding 5-arylvinyl ribavirin analogues (11a-g)16.
Scheme 2. Synthesis of 5-arylvinyltriazole nucleosides (11). Reagents and condition: (a) 20% mass Pd/C (10%), EtOH, rt, 24 hr, 86% yield; (b) 10 eq NaOCl, CH 2Cl2-H2O,rt, 1 hr, 77% yield; (c) K2CO3, rt, 24 hr, 4968% yield; (d) MeOH, rt, 48 hr, 61-81% yield. *- E/Z isomers are not separated. Preliminary in vitro assessment of the compounds (11a-g) showed low cytotoxicity, although compound (11d) showed moderate cytotoxicity (CC50=3.4 uM) against Vero 6 cells. Other compounds showed no cytotoxicity up to a concentration of 2 mM. All the compounds (11a-g) showed no cytotoxicity up to a concentration of 1 uM against Vero cells (CC50=0.3 uM for ribavirin). Preliminary antiviral evaluation of nucleosides (11a-g) against hepatitis C, influenza, and herpes simplex viruses was performed in vitro. The significant antiviral activity, comparable with that of ribavirin control, was observed only for compound 11b against herpes simplex virus type 1 (IC50=6.9 uM; IC50=10 uM for ribavirin) and for compound 11h against hepatitis C virus (HCV) (IC50=0.09 uM; IC50=0.04 uM for ribavirin). None of these compounds showed activity against influenza A H5N1 virus.
Using the proposed synthetic pathway to 5-arylvinyl ribavirin analogs we were able to obtain E- and Z-isomers of the target compounds. The isomer (11h) revealed antiviral activity similar to that of compounds (2) and (3), while its Z-isomer, compound (11g), was inactive. These results confirm the influence of the rigid bond between the triazole ring and aryl mojety on antiviral activity, however, steric molecular parameters were shown to make a more substantial contribution to activity than multiple bonds conjugation. This class of triazole nucleoside analogues bearing aromatic groups on the nucleobases possess activity against various virus types and as well as antitumor/anticancer activity9. There is no obvious correlation between antiviral activity and the structure of the other parts of the molecule, particularly its sugar part. Hence, compound (3) possesses high anti-HCV activity, and hydroxyl groups in its ribose residue are protected and therefore are not involved in the nucleoside metabolism. The protected analogue of compound (2) exhibited effective anticancer activity by inhibiting tumor growth in MiaPaCa2-xenograft nude mice6. In fact, the bioactivity mechanism for this class of compounds is still unclear and, possibly, it does not involve nucleoside metabolizing enzymes.
Acknowledgements This work was supported by Russian Foundation for Basic Research (project No. 14-03-31267), a grant of the president of Russian Federation for the state support of young scientists (MK-7350.2015.4) and a grant of the president of Russian Federation for the leading scientific school state support (7946.2016.11). We thank V.L. Andronova, G.A. Galegov and P.G. Deryabin from Ivanovsky Research Institute of Virology (Moscow, Russia) for their assistance in the antiviral evaluation. Supplementary data Supplementary data (experimental procedures and spectroscopic characterizations data of the compounds (5-11)) associated with this article can be found in the Electronic Supplementary Information (ESI).
Notes and references 1. Sidwell R. W.; Huffman J. H.; Khare G. P.; L. B. Allen; Witkowski J. T.; Robins R. K. Science 1972, 177, 705. 2. Graci J. D.; Cameron C. E. Rev Med Viro 2006, 16, 37. 3. Zeidler J.; Baraniak D.; Ostrowski T. Eur J Med Chem 2015, 97, 409. 4. Hahn F.E. In Mechanism of Action of Antieukaryotic and Antiviral Compounds; Hahn F.E. Ed., Springer Verlag: NY, 1979; pp 439 458. 5. Crotty S.; Cameron C.; Andino R. J Mol Med 2002, 80, 86. 6. Wan J.; Xia Y.; Liu Y.; Wang M.; Rocchi P.; Yao J.; Qu F.; Neyts J.; Iovanna J. L.; Peng L. J Med Chem 2009, 52, 1144. 7. Xia Y.; Liu Y.; Wan J.; Wang M.; Rocchi P.; Qu F.; Iovanna J. L.; Peng L. J Med Chem 2009, 52, 6083. 8. Wang M.; Xia Y.; Fan Y.; Rocchi P.; Qu F.; Iovanna J.L.; Peng L. Bioorg Med Chem Lett 2010, 20, 5979.
9. Xia Y.; Qu F.; Peng L. Mini-Reviews in Medicinal Chemistry, 2010, 10, 806. 10. Peng L.; Rocchi P. PCT Int. Appl. 2009, WO 2009133147 A1. 11. Neyts J.; Peng L.; Que F.; Zhu R. PCT Int. Appl. 2009, WO 2009015446 A2. 12. Tang J.; Cong M.; Xia Y.; Quéléver G.; Fan Y.; Qu F.; Peng L. Org Biomol Chem 2015, 13, 110. 13. Chudinov M.V.; Matveev A.V.; Prostakova V.I.; Shvets V.I. Vestnik MITHT 2011, 6, №2, 66 (in russian). 14. Chudinov M.V.; Matveev A.V.; Zhurilo N.I.; Prutkov A.N.; Shvets V.I. J Het Chem 2015, 52, 1273. 15. General procedure for synthesis of compound 10. The corresponding phosphonic salt (0.70 mmol) was suspended in 5 mL of anhydrous dichloromethane, to which were added under stirring 1.75 mmol of potassium carbonate and dibenzo-18-crown-6 as a catalyst. Then a solution of 0.70 mmol of aldehyde (9) in 5 mL of anhydrous dichloromethane was added. The mixture was stirred for 24 hr, after which the residue was filtered off and the solvent was evaporated in vacuo. Purification of the organic residue on 20 g of silica gel (eluent: petroleum ether-ethyl acetate (3:2)) afforded the title compound (10). 16. General procedure for synthesis of compound 11. 0.135 mmol of the protected nucleoside (10) was dissolved in 5 mL of 10M ammonia in methanol. The reaction mixture was stirred for 48 hr while 1 mL of 10M ammonia in methanol was added every 12 hours. The product formation was followed up by TLC (methanol – ethyl acetate 1:9). The solvent was then removed under reduced pressure and the product was purified by column chromatography on 1.5 g silica gel (eluent: gradient of CH3OH in ethyl acetate 0– 10%) affording the desired product.
S0960-894X(16)30570-4 http://dx.doi.org/10.1016/j.bmcl.2016.05.072 BMCL 23931
To appear in:
Bioorganic & Medicinal Chemistry Letters
Received Date: Revised Date: Accepted Date:
21 April 2016 23 May 2016 25 May 2016
Please cite this article as: Chudinov, M.V., Prutkov, A.N., Matveev, A.V., Grebenkina, L.E., Konstantinova, I.D., Berezovskaya, Y.V., An alternative route to the arylvinyltriazole nucleosides, Bioorganic & Medicinal Chemistry Letters (2016), doi: http://dx.doi.org/10.1016/j.bmcl.2016.05.072
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
An alternative route to the arylvinyltriazole nucleosides. Mikhail V. Chudinov a†, Alexander N. Prutkov a, Andrey V. Matveev a, Lyubov E. Grebenkina a, Irina D. Konstantinovab, Yulia V. Berezovskaya с a
Lomonosov Institute of Fine Chemical Tehnologies, Moscow Technological University, Vernadskogo Pr. 78, 119454, Russia. b Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, MiklukhoMaklaya St. 16/10, 117997 GSP, Moscow B-437, Russia. c Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudny, Moscow Region, 141700, Russia. † Corresponding author: [email protected] Abstract A new pathway to synthesis of arylvinyl ribavirin analogues is developed which makes it possible to obtain not only trans- but also cis-isomers at vinyl bond. By this route eight ribavirin 5-arylvinyl analogues are synthesized and their antiviral activity is evaluated.
In this article we focus on investigation of the structure-activity relationships for structure analogues of ribavirin (1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), an antiviral agent that has demonstrated efficacy in treating a wide range of viral diseases 1-2. Although several alternative mechanisms have been proposed by which ribavirin and its analogues may induce their antiviral activity3-5, there is still no consistent and comprehensive picture on this matter.
Figure 1. Anti-HCV nucleoside analogues: 1 - Ribavirine; 2-4 - the most active 5-aryl/alkylethynyl analogues6. A considerable antiviral and antitumour activity has been reported for ribavirin analogues bearing arylethynyl moieties at the 5th position of triazole ring 6-11. It was shown that replacing the triple bond from compound (2) (Fig. 1) with a flexible single bond led to the inactive analogues8. This was explained by the triple bond rigidity and therefore it indicates the existence of a correlation between structure of the moiety at the 5th position and the antiviral activity. Recently, Tang et al.12 offered the effective synthetic route to ribavirin 5-arylvinyl analogues bearing rigid double bond directly from the unprotected ribavirin using the oxidative Heck reaction. This approach allows one to obtain desired products with high yields but also has some disadvantages. Specifically, only trans-isomers can be obtained and the arylvinyl substituents variety is limited by starting styrene structures. We are particularly interested in the antiviral activity of 5-arylvinyl analogues and the structure-activity relationship for substituents at the 5th position of the triazole ring. While our new route to 5-arylvinyl ribavirin analogues gives desired products with lower general yields, it allows us to obtain not only trans- but also cis-isomers at vinyl bond; as a consequence this provides a wider molecular diversity including new 5-alkylvinyl ribavirin analogues. Thus, we are able to analyze the antiviral activity as a function of not only the substituent structure but also of the ethynyl linker double bond E/Z isomerism. The synthesis of arylvinyl ribavirin analogues was carried out via the Wittig reaction starting from the common precursor. To this end, ethyl 5-benzyloxymethyl-1H-1,2,4-triazole-3carboxylate (6), obtained by published method13-14, was glycosylated by D-ribose tetraacetate in the presence of bis(4-nitrophenyl) phosphate (Scheme 1). A mixture of 1- and 2-regioisomers (7) and (7а) was obtained in 5:1 ratio.
Scheme 1.
Synthesis of 5-benzyloxymethyl-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-[1,2,4]-triazole-3-
carboxylic acid ethyl ester (7). Reagents and condition: (a) EtOH, rt, 24 hr, 95% yield; (b) Py, refl, 5 hr, 59% yield; (c) 160◦C, 1 hr, 56% yield of (7). The nucleoside β-anomer (7) was separated by column chromatography on silica gel followed by debenzylation and subsequent oxidation to aldehyde (9) (Scheme 2). Then, the protected nucleosides (10a-g) were obtained by the reaction of the corresponding phosphonic salts 15. For the most part, isomeric ratio of products was obtained (approximately E:Z=1:1.25). As E- and Zisomers were separated they were converted to corresponding 5-arylvinyl ribavirin analogues (11a-g)16.
Scheme 2. Synthesis of 5-arylvinyltriazole nucleosides (11). Reagents and condition: (a) 20% mass Pd/C (10%), EtOH, rt, 24 hr, 86% yield; (b) 10 eq NaOCl, CH 2Cl2-H2O,rt, 1 hr, 77% yield; (c) K2CO3, rt, 24 hr, 4968% yield; (d) MeOH, rt, 48 hr, 61-81% yield. *- E/Z isomers are not separated. Preliminary in vitro assessment of the compounds (11a-g) showed low cytotoxicity, although compound (11d) showed moderate cytotoxicity (CC50=3.4 uM) against Vero 6 cells. Other compounds showed no cytotoxicity up to a concentration of 2 mM. All the compounds (11a-g) showed no cytotoxicity up to a concentration of 1 uM against Vero cells (CC50=0.3 uM for ribavirin). Preliminary antiviral evaluation of nucleosides (11a-g) against hepatitis C, influenza, and herpes simplex viruses was performed in vitro. The significant antiviral activity, comparable with that of ribavirin control, was observed only for compound 11b against herpes simplex virus type 1 (IC50=6.9 uM; IC50=10 uM for ribavirin) and for compound 11h against hepatitis C virus (HCV) (IC50=0.09 uM; IC50=0.04 uM for ribavirin). None of these compounds showed activity against influenza A H5N1 virus.
Using the proposed synthetic pathway to 5-arylvinyl ribavirin analogs we were able to obtain E- and Z-isomers of the target compounds. The isomer (11h) revealed antiviral activity similar to that of compounds (2) and (3), while its Z-isomer, compound (11g), was inactive. These results confirm the influence of the rigid bond between the triazole ring and aryl mojety on antiviral activity, however, steric molecular parameters were shown to make a more substantial contribution to activity than multiple bonds conjugation. This class of triazole nucleoside analogues bearing aromatic groups on the nucleobases possess activity against various virus types and as well as antitumor/anticancer activity9. There is no obvious correlation between antiviral activity and the structure of the other parts of the molecule, particularly its sugar part. Hence, compound (3) possesses high anti-HCV activity, and hydroxyl groups in its ribose residue are protected and therefore are not involved in the nucleoside metabolism. The protected analogue of compound (2) exhibited effective anticancer activity by inhibiting tumor growth in MiaPaCa2-xenograft nude mice6. In fact, the bioactivity mechanism for this class of compounds is still unclear and, possibly, it does not involve nucleoside metabolizing enzymes.
Acknowledgements This work was supported by Russian Foundation for Basic Research (project No. 14-03-31267), a grant of the president of Russian Federation for the state support of young scientists (MK-7350.2015.4) and a grant of the president of Russian Federation for the leading scientific school state support (7946.2016.11). We thank V.L. Andronova, G.A. Galegov and P.G. Deryabin from Ivanovsky Research Institute of Virology (Moscow, Russia) for their assistance in the antiviral evaluation. Supplementary data Supplementary data (experimental procedures and spectroscopic characterizations data of the compounds (5-11)) associated with this article can be found in the Electronic Supplementary Information (ESI).
Notes and references 1. Sidwell R. W.; Huffman J. H.; Khare G. P.; L. B. Allen; Witkowski J. T.; Robins R. K. Science 1972, 177, 705. 2. Graci J. D.; Cameron C. E. Rev Med Viro 2006, 16, 37. 3. Zeidler J.; Baraniak D.; Ostrowski T. Eur J Med Chem 2015, 97, 409. 4. Hahn F.E. In Mechanism of Action of Antieukaryotic and Antiviral Compounds; Hahn F.E. Ed., Springer Verlag: NY, 1979; pp 439 458. 5. Crotty S.; Cameron C.; Andino R. J Mol Med 2002, 80, 86. 6. Wan J.; Xia Y.; Liu Y.; Wang M.; Rocchi P.; Yao J.; Qu F.; Neyts J.; Iovanna J. L.; Peng L. J Med Chem 2009, 52, 1144. 7. Xia Y.; Liu Y.; Wan J.; Wang M.; Rocchi P.; Qu F.; Iovanna J. L.; Peng L. J Med Chem 2009, 52, 6083. 8. Wang M.; Xia Y.; Fan Y.; Rocchi P.; Qu F.; Iovanna J.L.; Peng L. Bioorg Med Chem Lett 2010, 20, 5979.
9. Xia Y.; Qu F.; Peng L. Mini-Reviews in Medicinal Chemistry, 2010, 10, 806. 10. Peng L.; Rocchi P. PCT Int. Appl. 2009, WO 2009133147 A1. 11. Neyts J.; Peng L.; Que F.; Zhu R. PCT Int. Appl. 2009, WO 2009015446 A2. 12. Tang J.; Cong M.; Xia Y.; Quéléver G.; Fan Y.; Qu F.; Peng L. Org Biomol Chem 2015, 13, 110. 13. Chudinov M.V.; Matveev A.V.; Prostakova V.I.; Shvets V.I. Vestnik MITHT 2011, 6, №2, 66 (in russian). 14. Chudinov M.V.; Matveev A.V.; Zhurilo N.I.; Prutkov A.N.; Shvets V.I. J Het Chem 2015, 52, 1273. 15. General procedure for synthesis of compound 10. The corresponding phosphonic salt (0.70 mmol) was suspended in 5 mL of anhydrous dichloromethane, to which were added under stirring 1.75 mmol of potassium carbonate and dibenzo-18-crown-6 as a catalyst. Then a solution of 0.70 mmol of aldehyde (9) in 5 mL of anhydrous dichloromethane was added. The mixture was stirred for 24 hr, after which the residue was filtered off and the solvent was evaporated in vacuo. Purification of the organic residue on 20 g of silica gel (eluent: petroleum ether-ethyl acetate (3:2)) afforded the title compound (10). 16. General procedure for synthesis of compound 11. 0.135 mmol of the protected nucleoside (10) was dissolved in 5 mL of 10M ammonia in methanol. The reaction mixture was stirred for 48 hr while 1 mL of 10M ammonia in methanol was added every 12 hours. The product formation was followed up by TLC (methanol – ethyl acetate 1:9). The solvent was then removed under reduced pressure and the product was purified by column chromatography on 1.5 g silica gel (eluent: gradient of CH3OH in ethyl acetate 0– 10%) affording the desired product.