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Leroy B. Townsend - One of the best experts on this subject based on the ideXlab platform.
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Design and synthesis of aCyCliC nuCleoside analogs with Chlorinated imidazo[1,2-a]pyridine bases.
Nucleosides nucleotides & nucleic acids, 2003Co-Authors: John D. Williams, John C. Drach, Alaa E. Mourad, Leroy B. TownsendAbstract:A series of aCyCliC C-nuCleoside analogs of 2,6-diChloro- and 2,6,7-triChloroimidazo[1,2-a]pyridine were synthesized and tested for antiviral aCtivity. The appropriate hydroxymethyl-substituted heteroCyCles were treated suCCessively with thionyl Chloride, an appropriate nuCleophile, then diisopropylethylamine to obtain the desired aCyCliC nuCleoside analogs. These Compounds were evaluated for aCtivity against human Cytomegalovirus and herpes simplex virus, type 1. Two of the diChloro analogs, but none of the triChloro analogs demonstrated slight antiviral aCtivity (IC50's = 20-45 miCroM) at non-CytotoxiC ConCentrations.
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The Synthesis of a New Pyrazolo[3,4-C]pyridine C-NuCleoside, StruCturallyRelated to FormyCin B
Synlett, 2002Co-Authors: Vassilios N. Kourafalos, Nicole Pouli, Panagiotis Marakos, Leroy B. TownsendAbstract:The first preparation of the 4-deaza analogue of formyCin B is desCribed, via the reaCtion of 3-aCetamido-2-methoxy-4-methylpyridine with a suitably proteCted ribonolaCtone and subsequent ring Closure to result in the 3-substituted pyrazolo[3,4-C]pyridine riboside 12.
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Synthesis of the First C3 Ribosylated Imidazo[1,2-a]pyridine C-NuCleoside by EnantioseleCtive ConstruCtion of the Ribose Moiety
The Journal of Organic Chemistry, 1998Co-Authors: Kristjan Gudmundsson, John C. Drach, Leroy B. TownsendAbstract:The metaboliC instability of the glyCosidiC linkage in 2,5,6-triChloro-1-(β-d-ribofuranosyl)benzimidazole prompted us to synthesize the struCturally related C-nuCleoside 2,6,7-triChloro-3-(β-d-ribofuranosyl)imidazo[1,2-a]pyridine. Synthesis of this first C3-ribofuranosylimidazo[1,2-a]pyridine was aCComplished by developing a modifiCation of existing iodoCyClization methodology for obtaining a 1‘,4‘-syn furanosyl preCursor, without an extensive proteCtion sCheme. This 1‘,4‘-syn preCursor was elaborated into the desired ribofuranosyl C-nuCleoside. X-ray Crystallography was used to unambiguously determine struCture and absolute stereoChemistry of this C-nuCleoside.
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Palladium Catalyzed Coupling of 2,6-DiChloro-3-iodoimidazo[1,2-a]pyridine and 2,3-dihydrofuran as an approaCh to novel imidazo[1,2-a]pyridine C-nuCleosides
Tetrahedron Letters, 1996Co-Authors: Kristjan Gudmundsson, John C. Drach, Leroy B. TownsendAbstract:Palladium was used for a Cross Coupling of 2,6-diChloro-3-iodoimidazo[1,2-a]pyridine (2) to 2,3-dihydrofuran (3). Optimization of the Coupling Conditions have given exClusively (+/−)-2,6-diChloro-3-(2′,5′-dihydrofuran-2′-yl)imidazo[1,2-a]pyridine (4) in high yield. Compound 4 was dihydroxylated using a CatalytiC amount of osmium tetroxide to give the erythrofuranosyl C-nuCleoside derivatives 6 and 7. This is the first report of a C-nuCleoside derivative Containing a sugar moiety attaChed to the C3 position of an imidazo[1,2-a]pyridine heteroCyCle.
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The Condensation of 2,6-diChloroimidazo[1,2-a]pyridine with ribonolaCtone gives a novel imidazo[1,2-a]pyridine C-nuCleoside with an unexpeCted site of ribosylation
Tetrahedron Letters, 1996Co-Authors: Kristjan Gudmundsson, John C. Drach, Leroy B. TownsendAbstract:AbstraCt A novel ribosylated imidazo[1,2-a]pyridine C-nuCleoside was synthesized by Condensing a lithiated 2,6-diChloroimidazo[1,2-a]pyridine ( 1 ) with a proteCted ribonolaCtone ( 2 ), followed by aCetylation to give the intermediate nuCleoside 4 . This intermediate was reduCtively deaCetoxylated and deproteCted to give what was determined to be the novel and unexpeCted 2,6-diChloro-5-(β-D-ribofuranosyl)imidazo[1,2-a]pyridine ( 7 ) and the Corresponding α-produCt ( 8 ). The site of ribosylation was established with long range proton-Carbon deCoupling experiments. This ribosylation at C5 was entirely unexpeCted in view of previously reported Condensations with lithiated imidazo[1,2-a]pyridines whiCh oCCurred only at the C3 position.
Yufen Zhao - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of substituted mono- and diindole C-nuCleoside analogues from sugar terminal alkynes by sequential sonogashira/heteroannulation reaCtion.
The Journal of organic chemistry, 2014Co-Authors: Fuyi Zhang, Liming Wang, Fen Han, Yufen ZhaoAbstract:The synthesis of substituted mono- and diindole C-nuCleoside analogues has been aChieved in good to exCellent yields by sequential Sonogashira Coupling/NaAuCl4-Catalyzed heteroannulation reaCtions of substituted 2-iodoanilines with various sugar terminal alkynes in one pot. The method is general, mild, and effiCient and suitable for a wide range of sugar substrates, and 42 examples are given. The amino group of the substituted 2-iodoanilines is unproteCted. The sugar terminal alkynes inClude furanosides, pyranosides, and aCyCliC glyCosides with free hydroxyl groups, sensitive funCtional subtituents, and various proteCting groups having different steriC hindranCe.
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novel syntheses of aryl quinoxaline C nuCleoside analogs by mild and effiCient three Component sequential reaCtions
Chemical Communications, 2014Co-Authors: Fuyi Zhang, Liming Wang, Linwei Liu, Yufen ZhaoAbstract:Novel syntheses of C-nuCleoside analogs with aryl quinoxalines as nuCleobase surrogates have been aCComplished by mild and effiCient three-Component sequential reaCtions in high yields with a wide sCope of substrates. The meChanism was Clarified by isolation of novel sugar 1,2-diketone derived from oxidation of the Corresponding alkyne.
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Synthesis of Substituted Mono- and Diindole C‑NuCleoside Analogues from Sugar Terminal Alkynes by Sequential Sonogashira/Heteroannulation ReaCtion
2014Co-Authors: Fuyi Zhang, Liming Wang, Fen Han, Yufen ZhaoAbstract:The synthesis of substituted mono- and diindole C-nuCleoside analogues has been aChieved in good to exCellent yields by sequential Sonogashira Coupling/NaAuCl4-Catalyzed heteroannulation reaCtions of substituted 2-iodoanilines with various sugar terminal alkynes in one pot. The method is general, mild, and effiCient and suitable for a wide range of sugar substrates, and 42 examples are given. The amino group of the substituted 2-iodoanilines is unproteCted. The sugar terminal alkynes inClude furanosides, pyranosides, and aCyCliC glyCosides with free hydroxyl groups, sensitive funCtional subtituents, and various proteCting groups having different steriC hindranCe
Marie E. Migaud - One of the best experts on this subject based on the ideXlab platform.
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novel synthetiC route to the C nuCleoside 2 deoxy benzamide riboside
ChemInform, 2012Co-Authors: Rebecca R. Midtkandal, Philip Redpath, Samuel A.j. Trammell, Simon J. F. Macdonald, Charles Brenner, Marie E. MigaudAbstract:The synthesis of 2-deoxy benzamide riboside (XI) proCeeds via the preparation of the m-vinyl substituted phenyl exo-alkene key intermediate (VII) whiCh provides the neCessary flexibility to aCCess the m-Carboxamide substituent, essential to benzamide riboside analogues.
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Novel synthetiC route to the C-nuCleoside, 2-deoxy benzamide riboside.
Bioorganic & medicinal chemistry letters, 2012Co-Authors: Rebecca R. Midtkandal, Philip Redpath, Samuel A.j. Trammell, Simon J. F. Macdonald, Charles Brenner, Marie E. MigaudAbstract:2-Deoxy-C-nuCleosides are a subCategory of C-nuCleosides that has not been explored extensively, largely beCause the synthesis is less faCile. Flexible synthetiC proCedures giving aCCess to 2-deoxy-C-nuCleosides are therefore of interest. To exemplify the versatility and highlight the limitations of a synthetiC route reCently developed to that effeCt, the first synthesis of 2-deoxy benzamide riboside is reported. BiologiCal properties of this novel C-nuCleoside are also disCussed.
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A regio- and stereoControlled approaCh to pyranosyl C-nuCleoside synthesis.
Organic letters, 2008Co-Authors: Philip Redpath, Simon J. F. Macdonald, Marie E. MigaudAbstract:Six novel diastereomeriCally pure C-nuCleosides have been synthesized from nonChiral starting materials, using the ene/intramoleCular Sakurai CyClization reaCtion demonstrating a simple, general, and stereoControlled approaCh to pyranosyl C-nuCleosides.
Kristjan Gudmundsson - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of the First C3 Ribosylated Imidazo[1,2-a]pyridine C-NuCleoside by EnantioseleCtive ConstruCtion of the Ribose Moiety
The Journal of Organic Chemistry, 1998Co-Authors: Kristjan Gudmundsson, John C. Drach, Leroy B. TownsendAbstract:The metaboliC instability of the glyCosidiC linkage in 2,5,6-triChloro-1-(β-d-ribofuranosyl)benzimidazole prompted us to synthesize the struCturally related C-nuCleoside 2,6,7-triChloro-3-(β-d-ribofuranosyl)imidazo[1,2-a]pyridine. Synthesis of this first C3-ribofuranosylimidazo[1,2-a]pyridine was aCComplished by developing a modifiCation of existing iodoCyClization methodology for obtaining a 1‘,4‘-syn furanosyl preCursor, without an extensive proteCtion sCheme. This 1‘,4‘-syn preCursor was elaborated into the desired ribofuranosyl C-nuCleoside. X-ray Crystallography was used to unambiguously determine struCture and absolute stereoChemistry of this C-nuCleoside.
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Palladium Catalyzed Coupling of 2,6-DiChloro-3-iodoimidazo[1,2-a]pyridine and 2,3-dihydrofuran as an approaCh to novel imidazo[1,2-a]pyridine C-nuCleosides
Tetrahedron Letters, 1996Co-Authors: Kristjan Gudmundsson, John C. Drach, Leroy B. TownsendAbstract:Palladium was used for a Cross Coupling of 2,6-diChloro-3-iodoimidazo[1,2-a]pyridine (2) to 2,3-dihydrofuran (3). Optimization of the Coupling Conditions have given exClusively (+/−)-2,6-diChloro-3-(2′,5′-dihydrofuran-2′-yl)imidazo[1,2-a]pyridine (4) in high yield. Compound 4 was dihydroxylated using a CatalytiC amount of osmium tetroxide to give the erythrofuranosyl C-nuCleoside derivatives 6 and 7. This is the first report of a C-nuCleoside derivative Containing a sugar moiety attaChed to the C3 position of an imidazo[1,2-a]pyridine heteroCyCle.
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The Condensation of 2,6-diChloroimidazo[1,2-a]pyridine with ribonolaCtone gives a novel imidazo[1,2-a]pyridine C-nuCleoside with an unexpeCted site of ribosylation
Tetrahedron Letters, 1996Co-Authors: Kristjan Gudmundsson, John C. Drach, Leroy B. TownsendAbstract:AbstraCt A novel ribosylated imidazo[1,2-a]pyridine C-nuCleoside was synthesized by Condensing a lithiated 2,6-diChloroimidazo[1,2-a]pyridine ( 1 ) with a proteCted ribonolaCtone ( 2 ), followed by aCetylation to give the intermediate nuCleoside 4 . This intermediate was reduCtively deaCetoxylated and deproteCted to give what was determined to be the novel and unexpeCted 2,6-diChloro-5-(β-D-ribofuranosyl)imidazo[1,2-a]pyridine ( 7 ) and the Corresponding α-produCt ( 8 ). The site of ribosylation was established with long range proton-Carbon deCoupling experiments. This ribosylation at C5 was entirely unexpeCted in view of previously reported Condensations with lithiated imidazo[1,2-a]pyridines whiCh oCCurred only at the C3 position.
Marc M. Greenberg - One of the best experts on this subject based on the ideXlab platform.
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Repair of DNA Containing Fapy·dG and its β-C-nuCleoside analogue by formamidopyrimidine DNA glyCosylase and MutY
Biochemistry, 2003Co-Authors: Carissa J. Wiederholt, Michael O. Delaney, Mary Ann Pope, Sheila S. David, Marc M. GreenbergAbstract:Fapy·dG is produCed in DNA as a result of oxidative stress. Under some Conditions Fapy·dG is formed in greater yields than 8-oxodG from a Common ChemiCal preCursor. ReCently, Fapy·dG and its C-nuCleoside analogue were inCorporated in ChemiCally synthesized oligonuCleotides at defined sites. Like 8-oxodG, Fapy·dG instruCts DNA polymerase to misinCorporate dA opposite it in vitro. The interaCtions of DNA Containing Fapy·dG or the nonhydrolyzable analogue with Fpg and MutY are desCribed. Fpg exCises Fapy·dG (KM = 2.0 nM, kCat = 0.14 min-1) opposite dC ∼17-fold more effiCiently than when mispaired with dA, whiCh is misinserted by DNA polymerase in vitro. Fpg also prefers to bind duplexes Containing Fapy·dG·dC or β-C-Fapy·dG·dC Compared to those in whiCh the lesion is opposite dA. MutY inCises dA when it is opposite Fapy·dG and strongly binds duplexes Containing the lesion or β-C-Fapy·dG. InCision from Fapy·dG·dA is faster than from dG·dA mispairs but slower than from DNA Containing 8-oxodG opposite dA. These ...
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repair of dna Containing fapy dg and its β C nuCleoside analogue by formamidopyrimidine dna glyCosylase and muty
Biochemistry, 2003Co-Authors: Carissa J. Wiederholt, Michael O. Delaney, Mary Ann Pope, Sheila S. David, Marc M. GreenbergAbstract:Fapy·dG is produCed in DNA as a result of oxidative stress. Under some Conditions Fapy·dG is formed in greater yields than 8-oxodG from a Common ChemiCal preCursor. ReCently, Fapy·dG and its C-nuCleoside analogue were inCorporated in ChemiCally synthesized oligonuCleotides at defined sites. Like 8-oxodG, Fapy·dG instruCts DNA polymerase to misinCorporate dA opposite it in vitro. The interaCtions of DNA Containing Fapy·dG or the nonhydrolyzable analogue with Fpg and MutY are desCribed. Fpg exCises Fapy·dG (KM = 2.0 nM, kCat = 0.14 min-1) opposite dC ∼17-fold more effiCiently than when mispaired with dA, whiCh is misinserted by DNA polymerase in vitro. Fpg also prefers to bind duplexes Containing Fapy·dG·dC or β-C-Fapy·dG·dC Compared to those in whiCh the lesion is opposite dA. MutY inCises dA when it is opposite Fapy·dG and strongly binds duplexes Containing the lesion or β-C-Fapy·dG. InCision from Fapy·dG·dA is faster than from dG·dA mispairs but slower than from DNA Containing 8-oxodG opposite dA. These ...