101
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Doboszewski B. D-Arabinose-based synthesis of homo-C-d4T and homo-C-thymidine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2010; 28:875-901. [PMID: 20183559 DOI: 10.1080/15257770903306518] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
2,3,5-Tri-O-benzyl-D-arabinofuranosyl halides (chloride, bromide) were reacted with AllMgBr, MeMgBr, and VinMgBr to furnish anomeric mixtures of the C-glycosyl products. The factors that influenced the beta/alpha ratio are discussed. The alpha,beta-C-vinyl derivative was transformed into 1-deoxy-1-C-hydroxymethyl-beta- and -alpha-D-arabinofuranoses (2,5-anhydro-D-glucitol and -mannitol, respectively), separable after isopropylidenation step. 2,5-Anhydro-1,3-O-isopropylidene-D-glucitol was converted into 2,5-anhydro-6-O-triphenylmethyl-D-erythro-hex-3,4-enitol and 2,5-anhydro-4,6-di-O-benzoyl-3-deoxy-D-ribo-hexitol, which were coupled with N-3-benzoylthymine under the Mitsunobu conditions to furnish two analogs of nucleosides with a -CH(2)- insert between sugar moieties and thymine.
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Affiliation(s)
- Bogdan Doboszewski
- Departmento de Química, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil.
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102
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Boto A, Hernández D, Hernández R. One-Pot Synthesis of Azanucleosides from Proline Derivatives - Stereoselectivity in Sequential Processes. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000360] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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103
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Szostak M, Yao L, Aubé J. Synthesis of medium-bridged twisted lactams via cation-pi control of the regiochemistry of the intramolecular Schmidt reaction. J Org Chem 2010; 75:1235-43. [PMID: 20095596 DOI: 10.1021/jo902574m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Medium-bridged twisted amides can be synthesized by the intramolecular Schmidt reaction of 2-azidoalkyl ketones. In these reactions, the regiochemistry of the Schmidt reaction is diverted into a typically disfavored pathway by the presence of an aromatic group at the alpha-position adjacent to the ketone, which stabilizes the predominantly reactive conformation of the azidohydrin intermediate by engaging in a nonbonded cation-pi interaction with the positively charged diazonium cation. This results in the rarely observed rearrangement of the C-C bond distal to the azidoalkyl chain. This reaction pathway also requires the azide-containing tether to be situated in the axial orientation in the key azidohydrin intermediate. Examination of the effect of substitution of aromatic rings on the regiochemistry of the Schmidt reaction shows an increase in the migratory selectivity with more electron-rich aromatic groups. The selectivity is lower when an electron-withdrawing substituent is placed on the aromatic ring. The ability of cation-pi interactions to act as a controlling element decreases when Lewis acids coordinate to substituents on the aromatic ring. The developed version of the Schmidt reaction provides a direct access to a family of medium-bridged twisted amides with a [4.3.1] bicyclic system, compounds which are very difficult to access with use of other currently available methods.
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Affiliation(s)
- Michal Szostak
- Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Malott Hall, Room 4070, Lawrence, Kansas 66045-7852, USA
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104
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Friestad GK, Lee HJ. Trans-2,5-Disubstituted Tetrahydrofurans via Addition of Carbon Nucleophiles to the Strained Bicyclic Acetal 2,7-Dioxabicyclo[2.2.1]heptane. Org Lett 2009; 11:3958-61. [DOI: 10.1021/ol901613k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Hye Jin Lee
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242
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105
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Computational studies of the role of glycopyranosyl oxacarbenium ions in glycobiology and glycochemistry. Adv Carbohydr Chem Biochem 2009; 62:83-159. [PMID: 19501705 DOI: 10.1016/s0065-2318(09)00004-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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106
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Brinzari TV, Tian C, Halder GJ, Musfeldt JL, Whangbo MH, Schlueter JA. Color Properties and Structural Phase Transition in Penta- And Hexacoordinate Isothiocyanato Ni(II) Compounds. Inorg Chem 2009; 48:7650-8. [DOI: 10.1021/ic802120n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- T. V. Brinzari
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996
| | - C. Tian
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204
| | - G. J. Halder
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - J. L. Musfeldt
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996
| | - M.-H. Whangbo
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204
| | - J. A. Schlueter
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439
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107
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Enantiopure alkaloid analogues and iminosugars from proline derivatives: stereocontrol in sequential processes. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.04.082] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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108
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Abstract
A wide variety of p-tolyl thioriboside donors are examined for O-ribosylations of primary and secondary alcohols. p-Tolylsulfenyl trifluoromethanesulfonate (p-TolSOTf) is very effective in promoting O-ribosylations with p-tolyl thioriboside; all reactions are completed within 1-15 min to provide the desired products in good yield with reliable alpha/beta selectivity. A wide range of functional groups are tolerated under these conditions. The described O-ribosylation conditions are very useful for the generation of ribosaminouridine library molecules in solution or on polymer support.
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Affiliation(s)
- Michio Kurosu
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 1682 Campus Delivery, Fort Collins, Colorado 80523-1682, USA.
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109
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Ribelin T, Katz CE, English DG, Smith S, Manukyan AK, Day VW, Neuenswander B, Poutsma JL, Aubé J. Highly stereoselective ring expansion reactions mediated by attractive cation-n interactions. Angew Chem Int Ed Engl 2008; 47:6233-5. [PMID: 18613179 DOI: 10.1002/anie.200801591] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Timothy Ribelin
- Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Malott Hall, Room 4070, Lawrence, KS 66047, USA
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110
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Ribelin T, Katz C, English D, Smith S, Manukyan A, Day V, Neuenswander B, Poutsma J, Aubé J. Highly Stereoselective Ring Expansion Reactions Mediated by Attractive Cation-n Interactions. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801591] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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111
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Löpfe M, Siegel JS. Diastereoselective synthesis of 2',3'-dideoxy-beta-C-glucopyranosides as intermediates for the synthesis of 2',3'-dideoxy-beta-D-glucopyranosyl-C-nucleosides. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2008; 26:1029-35. [PMID: 18058531 DOI: 10.1080/15257770701508695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
An extension of the Vorbrüggen method of nucleotide synthesis for the synthesis of C-glucopyranosides, as intermediates for C-nucleosides, is described. It could be shown that the diastereoselectivity of the reaction can be tuned by a simple change of protecting groups.
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Affiliation(s)
- Michael Löpfe
- Institute of Organic Chemistry, University of Zurich, Zurich, Switzerland
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112
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113
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Beaver MG, Billings SB, Woerpel KA. Nucleophilic Substitution Reactions of 2‐Phenylthio‐Substituted Carbohydrate Acetals and Related Systems: Episulfonium Ions vs. Oxocarbenium Ions as Reactive Intermediates. European J Org Chem 2008. [DOI: 10.1002/ejoc.200700911] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Matthew G. Beaver
- Department of Chemistry, University of California, Irvine, California 92697‐2025, USA, Fax: +1‐949‐824‐9920
| | - Susan B. Billings
- Department of Chemistry, University of California, Irvine, California 92697‐2025, USA, Fax: +1‐949‐824‐9920
| | - K. A. Woerpel
- Department of Chemistry, University of California, Irvine, California 92697‐2025, USA, Fax: +1‐949‐824‐9920
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114
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Gooseman N, O'Hagan D, Peach M, Slawin A, Tozer D, Young R. An ElectrostaticGauche Effect in β-Fluoro- and β-Hydroxy-N-ethylpyridinium Cations. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200700714] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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115
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Gooseman NEJ, O'Hagan D, Peach MJG, Slawin AMZ, Tozer DJ, Young RJ. An ElectrostaticGauche Effect in β-Fluoro- and β-Hydroxy-N-ethylpyridinium Cations. Angew Chem Int Ed Engl 2007; 46:5904-8. [PMID: 17610229 DOI: 10.1002/anie.200700714] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Natalie E J Gooseman
- School of Chemistry and Centre for Biomolecular Sciences, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9ST, UK
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116
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Whitfield DM, Nukada T. DFT studies of the role of C-2–O-2 bond rotation in neighboring-group glycosylation reactions. Carbohydr Res 2007; 342:1291-304. [DOI: 10.1016/j.carres.2007.03.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/26/2007] [Accepted: 03/30/2007] [Indexed: 11/15/2022]
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117
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Whitfield DM. DFT studies of the ionization of alpha and beta glycopyranosyl donors. Carbohydr Res 2007; 342:1726-40. [PMID: 17555731 DOI: 10.1016/j.carres.2007.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 04/26/2007] [Accepted: 05/06/2007] [Indexed: 11/28/2022]
Abstract
Current attempts at mimicking the transition states (TSs) of glycosyl processing enzymes (GPEs) that proceed through TSs with a high degree of oxacarbenium ion formation suffer from a paucity of data about the conformations of such oxacarbenium ions. Because TSs are maxima, the current models based on minimized structures may need some refinement. As part of studies directed at optimizing chemical glycosylation the ionization of 3,4,6-tri-O-acetyl-alpha/beta-D-glucopyranosyl chlorides and triflates, 2,3,4,6-tetra-O-methyl-alpha/beta-D-glucopyranosyl fluorides, chlorides and triflates, 2,3,4,6-tetra-O-methyl-alpha/beta-D-mannopyranosyl fluorides, 2,3-di-O-methyl 4,6-O-benzylidene alpha/beta-D-mannopyranosyl triflates and 2,3-di-O-methyl 4,6-O-benzylidene alpha/beta-D-glucopyranosyl triflates was studied by a prototypic density functional theory (DFT) procedure. In all cases, the alpha-anomers ionized smoothly to 4H3 half chair conformations or adjacent envelopes. By contrast, all beta-anomers exhibited an abrupt conformational change before ionization was complete. The nature of the conformations sampled depends on both the leaving group and the protecting group. The methods presented can be readily adapted to the study of any GPE or chemical glycosylation and provide a method for initial evaluation of plausible TSs, which in turn can be used in mimetic design.
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Affiliation(s)
- Dennis M Whitfield
- Institute for Biological Sciences, NRC Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6.
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118
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Crich D, Vinogradova O. On the influence of the C2-O2 and C3-O3 bonds in 4,6-O-benzylidene-directed beta-mannopyranosylation and alpha-glucopyranosylation. J Org Chem 2006; 71:8473-80. [PMID: 17064022 PMCID: PMC2621314 DOI: 10.1021/jo061417b] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of 4,6-O-benzylidene-protected 2-deoxyarabino-, 3-deoxyarabino-, and 3-deoxyribothioglycosides is described and their glycosylation reactions, with activation by either 1-benzenesulfinyl piperidine/trifluoromethansulfonic anhydride or diphenyl sulfoxide/trifluoromethanesulfonic anhydride, studied. In contrast to the corresponding 4,6-O-benzylidene-protected glucosyl and mannosyl donors, which are alpha- and beta-selective, respectively, poor diastereoselectivity is observed in all cases. The reasons for this poor selectivity are discussed in terms of the interaction between the C2-O2 and C3-O3 bonds in the glucosyl and mannosyl donors and of the influence of this interaction on the ease of formation of the intermediate glycosyl oxacarbenium ions.
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Affiliation(s)
- David Crich
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA.
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