- Isotope studies of the transfer of the carbon atoms of carbohydrate derivatives into aromatic compounds (especially xanthene) under degradation conditions
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Treatment of various 13C-carbohydrate-labelled phenyl β-D-glucopyranosides at 350°C in aqueous phenol in the presence of zinc chloride, with 13C NMR analysis of the xanthene formed as the major neutral product, indicated that the methylene carbon atom (C-9) of this compound was derived from C-1 (30%), C-2 (20%), and C-6 (50%) of the glucosyl units. In addition, 4.5% of the carbon from the sugar was incorporated into the aromatic rings of the xanthene. Mass spectrometry of the phenol produced on heating methyl α-D-glucopyranoside (50% U-13C) at 350°C for 1 h in aqueous zinc chloride showed the aromatic rings to be derived from the glucosyl moiety, partly without cleavage of the carbon chain and also after cleavage and recombination of the fragments.
- Ferrier,Severn,Furneaux,Miller
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Read Online
- Scope of the DMC mediated glycosylation of unprotected sugars with phenols in aqueous solution
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Activation of reducing sugars in aqueous solution using 2-chloro-1,3-dimethylimidazolinium chloride (DMC) and triethylamine in the presence of para-nitrophenol allows direct stereoselective conversion to the corresponding 1,2-Trans para-nitrophenyl glycosides without the need for any protecting groups. The reaction is applicable to sulfated and phosphorylated sugars, but not to ketoses or uronic acids or their derivatives. When applied to other phenols the product yield was found to depend on the pKa of the added phenol, and the process was less widely applicable to 2-Acetamido sugars. For 2-Acetamido substrates an alternative procedure in which the glycosyl oxazoline was pre-formed, the reaction mixture freeze-dried, and the crude product then reacted with an added phenol in a polar aprotic solvent system with microwave irradiation proved to be a useful simplification.
- Fairbanks, Antony J.,Qiu, Xin
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p. 7355 - 7365
(2020/10/13)
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- Phenyl glycosides – Solid-state NMR, X-ray diffraction and conformational analysis using genetic algorithm
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The X-ray structures of 2,6-dimethylphenyl and phenyl 2,3,4,6-tetra-O-acetyl β-glucosides (1 and 3) and phenyl α-mannoside (6) were obtained. The independent part of the unit cell of the glycosides 1 and 6 was formed by one molecule, and for the glucoside 3, two molecules in the crystal cell were observed. In deacetylated glycosides 4 and 6 the crystal structure was established by a hydrogen bond network formed between the sugar hydroxyls and solvent molecules. The 13C CPMAS NMR spectra of aryl glycosides 1–6 were analysed. In the spectrum of 3, doubling of the C4 aryl signal was observed which confirmed the presence of two independent molecules in the solid sample. The GAAGS (Genetic Algorithm-Assisted Grid Search) method was used to determine the low-energy conformers of α-mannosides and β-glucosides. The orientation of the aryl pendant group was calculated using Molecular Mechanics (MMFF94) as well as Quantum Mechanics theory (DFT, B3LYP/6-31 + G(d,p)).
- Wa?ejko, Piotr,Bukowicki, Jaros?aw,Dobrzycki, ?ukasz,Socha, Pawe?,Paradowska, Katarzyna
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p. 126 - 136
(2019/01/03)
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- Deacetylation of per-acetatylated glycopyranosides: An overall pattern for acidic catalyzis
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Acetyl protecting groups are commonly used in carbohydrate chemistry. Partially acetylated arylglycosides are not only useful building blocks in syntheses, but they are also substantial for plant metabolism. Nonselective base catalysis is often used for removing the acetyl groups. Even though acid-catalyzed deacetylation might be more selective, it is seldom used in carbohydrate chemistry, because it has not been thoroughly investigated. In this work, we study the acid-catalyzed deacetylation of per-acetylated phenyl glycosides experimentally and computationally by using density functional theory (DFT) calculations. Based on quantum modeling, we design a general scheme for the stepwise acid-catalyzed deacetylation of arylglycosides per-acetates. The approach can also be applied on gluco- and galactopyranosides. We have studied the deacetylation reaction in solvents of different polarity and found that the activation barriers of the stepwise deacetylation mechanism increase with increasing polarity of the solvent.
- Nasibullin,Valiev,Faiskanova,Stepanova,Cherepanov,Filimonov,Sundholm
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p. 123 - 127
(2019/03/26)
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- Rapid phenolic O-glycosylation of small molecules and complex unprotected peptides in aqueous solvent
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Glycosylated natural products and synthetic glycopeptides represent a significant and growing source of biochemical probes and therapeutic agents. However, methods that enable the aqueous glycosylation of endogenous amino acid functionality in peptides without the use of protecting groups are scarce. Here, we report a transformation that facilitates the efficient aqueous O-glycosylation of phenolic functionality in a wide range of small molecules, unprotected tyrosine, and tyrosine residues embedded within a range of complex, fully unprotected peptides. The transformation, which uses glycosyl fluoride donors and is promoted by Ca(OH)2, proceeds rapidly at room temperature in water, with good yields and selective formation of unique anomeric products depending on the stereochemistry of the glycosyl donor. High functional group tolerance is observed, and the phenol glycosylation occurs selectively in the presence of virtually all side chains of the proteinogenic amino acids with the singular exception of Cys. This method offers a highly selective, efficient, and operationally simple approach for the protecting-group-free synthesis of O-aryl glycosides and Tyr-O-glycosylated peptides in water.
- Wadzinski, Tyler J.,Steinauer, Angela,Hie, Liana,Pelletier, Guillaume,Schepartz, Alanna,Miller, Scott J.
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p. 644 - 652
(2018/05/04)
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- A new look at acid catalyzed deacetylation of carbohydrates: A regioselective synthesis and reactivity of 2-O-acetyl aryl glycopyranosides
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In the present work we report that acetyl groups of per – acetylated aryl glycosides have different reactivity during the acidic deacetylation using HCl/EtOH in CHCl3, which leads to preferential deacetylation at O-3, O-4 and O-6. Thereby, the one-step preparation of 2-O-acetyl aryl glycosides with simple aglycon was accomplished for the first time. It was proved that the found reagent is to be general and unique for the preparation of series of 2-О-acetyl aryl glycosides. We have determined the influence of both carbohydrate moiety and the aglycon on the selectivity of deacetylation reaction by kinetic experiments. Using DFT/B3LYP/6-31G(d,p) and semi-empirical АМ1 methods we have found that the highest activation barrier is for 2-О-acetyl group. This completely explains the least reactivity of 2-О-acetyl group.
- Stepanova, Elena V.,Nagornaya, Marina O.,Filimonov, Victor D.,Valiev, Rashid R.,Belyanin, Maxim L.,Drozdova, Anna K.,Cherepanov, Victor N.
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supporting information
p. 60 - 66
(2018/02/20)
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- PHENOL GLYCOSIDES AND THEIR USE IN THE TREATMENT OF UROLITHIASIS
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The present invention relates to novel derivatives of polyphenol glycoside or polyalcohols of formula (1), wherein R1, R2, R3 is selected from the group consisting of H, OH, C(O)R4, C(0) OR4, 0 (Gly H3)n, wherein n = 0 1, 2, 3, and R4 is selected from the group consisting of H, alkyl, and Gly is a mono- or disaccharide residue. The present invention also relates to novel derivatives of glycoside polyphenols or polyalcohols, as pharmaceutical composition comprising a novel polyphenol glycoside or polyalcohols and the use of novel polyphenol glycoside or polyalcohols for the treatment of urolithiasis.
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Page/Page column 26; 27; 32
(2017/01/26)
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- Selective C?O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ
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Described herein is the selective reduction of sugars with hydrosilanes catalyzed by using Piers’ borane [(C6F5)2BH] generated in situ. The hydrosilylative C?O bond cleavage of silyl-protected mono- and disaccharides in the presence of a (C6F5)2BH catalyst, generated in situ from (C6F5)2BOH, takes place with excellent chemo- and regioselectivities to provide a range of polyols. A study of the substituent effects of sugars on the catalytic activity and selectivity revealed that the steric environment around the anomeric carbon (C1) is crucial.
- Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
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supporting information
p. 13757 - 13761
(2017/10/09)
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- COMPOUNDS AND METHODS FOR TREATING BACTERIAL INFECTIONS
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The present invention encompasses compounds and methods for treating urinary tract infections.
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Page/Page column 69-70
(2011/05/06)
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- FimH antagonists for the oral treatment of urinary tract infections: From design and synthesis to in vitro and in vivo evaluation
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Urinary tract infection (UTI) by uropathogenic Escherichia coli (UPEC) is one of the most common infections, particularly affecting women. The interaction of FimH, a lectin located at the tip of bacterial pili, with high mannose structures is critical for the ability of UPEC to colonize and invade the bladder epithelium. We describe the synthesis and the in vitro/in vivo evaluation of α-d-mannosides with the ability to block the bacteria/host cell interaction. According to the pharmacokinetic properties, a prodrug approach for their evaluation in the UTI mouse model was explored. As a result, an orally available, low molecular weight FimH antagonist was identified with the potential to reduce the colony forming units (CFU) in the urine by 2 orders of magnitude and in the bladder by 4 orders of magnitude. With FimH antagonist 16b, the great potential for the effective treatment of urinary tract infections with a new class of orally available antiinfectives could be demonstrated.
- Klein, Tobias,Abgottspon, Daniela,Wittwer, Matthias,Rabbani, Said,Herold, Janno,Jiang, Xiaohua,Kleeb, Simon,Lüthi, Christine,Scharenberg, Meike,Bezen?on, Jacqueline,Gubler, Erich,Pang, Lijuan,Smiesko, Martin,Cutting, Brian,Schwardt, Oliver,Ernst, Beat
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supporting information; experimental part
p. 8627 - 8641
(2011/02/28)
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- The building blocks of cellulose: The intrinsic conformational structures of cellobiose, its epimer, lactose, and their singly hydrated complexes
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A combination of vibrational spectroscopy conducted under molecular beam conditions and quantum chemical calculation has established the intrinsic three-dimensional structures of the cellulose disaccharide and, focusing on the critical β1,4-linkage at the nonreducing end of the growing cellulose polymer, its C-4′ epimer. Left to their own devices they both adopt a cis (anti-φ/syn-ψ) glycosidic configuration, supported in the epimer by strong, cooperative inter-ring hydrogen bonding. In the cellulose disaccharide, however, where the OH-4′(Glc) group is equatorial, the cooperativity is reduced and the corresponding inter-ring hydrogen bonding is relatively weak. The cis conformational preference is still retained in their singly hydrated complexes. In the cellulose disaccharide insertion of the water molecule at the favored binding site between OH-4′ and the neighboring hydroxyl group OH-6′ promotes a structural reorganization to create a configuration that parallels that of its unhydrated epimer and greatly strengthens the inter-ring hydrogen bonding. In the C-4′ epimer, the axial orientation of OH-4′ blocks this binding site and the bound water molecule simply adds on at the end of the (OH-O)n chain, which has a negligible effect on the (already strong) inter-ring bonding. The implications of these results are discussed with respect to the structure and insolubility of native cellulose polymers.
- Cocinero, Emilio J.,Gamblin, David P.,Davis, Benjamin G.,Simons, John P.
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supporting information; experimental part
p. 11117 - 11123
(2009/12/03)
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- Photolabile protection of 1,2- and 1,3-diols with salicylaldehyde derivatives
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(Chemical Equation Presented) 1,2- and 1,3-diols, including carbohydrates, can be readily caged as acetals of 5-methoxy- or 5-hydroxysalicylaldehydes. Irradiation of these acetals with 300 nm light results in their efficient (Φ = 0.2-0.3) cleavage, regenerating an aldehyde and a glycol in excellent chemical yield. Photoreactive 5-hydroxysalicylaldehyde acetals can be produced by mild in situ reduction of photostable p-quinone precursors.
- Kostikov, Alexey P.,Popik, Vladimir V.
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scheme or table
p. 5277 - 5280
(2009/06/18)
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- Probing the aglycon promiscuity of an engineered glycosyltransferase
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(Figure Presented) A sweet library: Two variants (wild-type (WT) and a triple mutant) of glycosyltransferase (GT) OleD have been shown to catalyze glycosylation of over 70 substrates, formation of O-, S- and N-glycosidic bonds, and iterative glycosylation (see scheme). Identified substrates include nucleophiles not previously known to act in GT reactions and span numerous natural product and therapeutic drug classes.
- Gantt, Richard W.,Goff, Randal D.,Williams, Gavin J.,Thorson, Jon S.
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supporting information; experimental part
p. 8889 - 8892
(2009/05/26)
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- Simple and efficient MW-assisted cleavage of acetals and ketals in pure water
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Simple and efficient MW-assisted cleavage of acetal and ketal is proposed in deionized water and in a very short time.
- Procopio, Antonio,Gaspari, Marco,Nardi, Monica,Oliverio, Manuela,Tagarelli, Antonio,Sindona, Giovanni
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p. 8623 - 8627
(2008/03/30)
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- Mild and efficient method for the cleavage of benzylidene acetals by using erbium (III) triflate
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Er(OTf)3 is proposed as new efficient Lewis acid catalyst in a mild deprotection protocol of benzylidene derivatives. In a modified procedure, where acetic anhydride is used as the reaction solvent, the simultaneous cleavage of the benzylidene acetal and the peracetylation of the substrates is obtained in quantitative yields and very short reaction times. The Royal Society of Chemistry 2005.
- Procopio, Antonio,Dalpozzo, Renato,De Nino, Antonio,Maiuolo, Loredana,Nardi, Monica,Romeo, Giovanni
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p. 4129 - 4133
(2007/10/03)
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- Recoverable, Reusable, Highly Active, and Sulfur-Tolerant Polymer Incarcerated Palladium for Hydrogenation
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A new type of immobilized palladium, PI (polymer incarcerated) Pd (2b), from Pd(PPh3)4 and copolymer (1b) has been developed. The excellent activity of PI Pd has been demonstrated in hydrogenation of various olefins, benzyl ethers, and nitro and aromatic compounds. PI Pd is tolerant under high pressure and high temperature and can be recovered and reused several times without loss of activity even under harsh conditions. Moreover, PI Pd is highly resistant to poisoning by sulfur.
- Okamoto, Kuniaki,Akiyama, Ryo,Kobayashi, Shu
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p. 2871 - 2873
(2007/10/03)
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- Novel reaction systems for the synthesis of O-glucosides by enzymatic reverse hydrolysis
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Our studies are presented to replace alcohols as solvents in reverse hydrolytic reactions catalyzed by immobilized β-glucosidase to synthesize O-substituted β-D-glucopyranosides in preparative-scale. We found that 1,2-diacetoxyethane is a suitable solvent and O-alkyl or aryl β-D-glucosides were synthesized in moderate yields (after isolation 12-19%). In these reactions proportion of glucose and glucosyl acceptor hydroxy compounds was 1:20. We suggest that 1,2-diacetoxyethane can be useful not only for alcohols but for other glucosyl donor compounds unsuitable for the role of solvent (e.g., phenols) in the synthesis of O-β-D-glucosides by reverse hydrolysis.
- Balogh, Teréz,Boross, László,Kosáry, Judit
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p. 679 - 682
(2007/10/03)
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- Process for the preparation of tetrahydropyran derivatives
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A process of making arbutin and its derivatives comprises solvolyzing an acylated precursor of arbutin or its derivative in a solution comprising an organic solvent and a base, neutralizing the solution with an acid, and crystillizing the product arbutin or its derivative. The process may be employed on an industrial scale and avoids the use of ion exchange columns. The process has the advantages of not requiring ion exchange columns and peripheral devices, which leads to cost and time savings, due to the elimination of column regeneration steps. Waste water from column regeneration is also eliminated.
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- The improved synthesis of β-D-Glucuronides using TEMPO and t-butyl hypochlorite
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TEMPO/t-BuOCl is used to oxidise β-D-glucosides to β-D-glacuronides in high yield as a pivotal step in the preparation of labelled glucuronides from labelled glucose samples.
- Melvin,McNeill,Henderson,Herbert
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p. 1201 - 1202
(2007/10/03)
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- Regioselective Lipase-catalysed acylation of 4,6-O-benzylidene-α- and - β-D-pyranoside derivatives displaying a range of anomeric substituents
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The application of Lipase enzymes to effect regioselective C-3-O- acylation of 4,6-O-benzylidene-β-D-gluco- and -galactopyranosides displaying a range of anomeric substituents, and C-2-O-acylation of phenyl 4,6-O- benzylidene-α-D-glucopyranoside and ethyl 4,6-O-benzylidene-1-thio-α-D- glucopyranoside is reported. In particular this method has allowed introduction of a variety of acyl protecting groups at the C-3 hydroxyl group of ethyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside 11.
- Gridley, Jonathan J.,Hacking, Andrew J.,Osborn, Helen M. I.,Spackman, David G.
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p. 14925 - 14946
(2007/10/03)
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- Preparative Bioorganic Chemistry, XVI. Synthesis of 3,4'-Dihydroxypropiophenone 3-&β-D-Glucopyranoside, a Constituent of Betula platyphylla var. japonica, by Enzymatic Transglucosylation
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3,4'-Dihydroxypropiophenone 3-β-D-glucopyranoside (1a) has been synthesized, without having recourse to any protective group technology, by transglucosylation catalyzed by lactase from Kluyveromyces lactis. Key words: Antifeedant; Betula platyphylla; β-D-glucopyranoside; lactase; transglucosylation.
- Mori, Kenji,Qian, Zhao-Hui,Watanabe, Sadamoto
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p. 485 - 488
(2007/10/02)
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- Stannic chloride promoted synthesis of mannosides
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Use of anhyd.SnCl4 has been described for the synthesis of aryl, arylalkyl and alkyl α-D-mannopyranosides.A possible mechanism for the formation of α-anomer in these reactions is discussed.
- Irani, Rustom K,Sinha, Bharati,Bose, J L
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p. 519 - 521
(2007/10/02)
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- Solvolysis of D-Glucopyranosyl Derivatives in Mixtures of Ethanol and 2,2,2-Trifluoroethanol
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The products of solvolysis of α- and β-D-glucopyranosyl fluorides, 2,4-dinitrophenyl β-D-glucopyranoside, and the trifluoromethanesulfonates of the β-D-glucopyranosyl 3-bromopyridinium and α-D-glucopyranosyl 4-methylpyridinium ions in an equimolar mixture of ethanol and trifluoroethanol buffered with ca. 2 equiv of 2,6-lutidine have been examined by GLC of their trimethylsilyl ethers.The initial products of the solvolyses of phenyl α- and β-D-glucopyranosides catalyzed by trifluoromethanesulfonic acid in an equimolar mixture of ethanol and trifluoroethanol, and the products of uncatalyzed solvolysis of β-D-glucopyranosyl-p-nitrophenyltriazene, have been likewise examined.The composition of the medium for solvolysis of the glucosyl fluorides has also been systematically varied from pure ethanol to pure trifluoroethanol.The percentage of products with the same anomeric configuration as the starting material is in the range 8.1-88.5percent; change of leaving group, at constant anomeric configuration, or of anomeric configuration, at constant leaving group, yields different product distributions.Therefore the transition state for the product-determining step contains the leaving group.The preference for attack by ethanol as compared with trifluoroethanol varies from 0.9 to 20 in a way which shows no general systematic distinction between pathways for retention or inversion.The nucleophilic selectivity for retention is lowered by anionic leaving groups, especially fluoride, which preferentially stabilize the transition state containing trifluoroethanol by hydrogen bonding.Nucleophilic attack at the α face is preferred over nucleophilic attack at the β face, and exibits a lower selectivity: this is ascribed to hydrogen bonding between the oxygen atom of the 2-hydroxyl group and the hydroxyl group of the approaching alcohol.A model for solvolysis involving a reversibly formed ion pair or encounter complex is incompatible with the selectivities still observed with leaving groups less nucleophilic than the solvent components: a model involving selection between the components of a pool of solvent molecules by an irreversibly formed ion pair or encounter complex requires an implausibly large pool to explain observed specificities.It is therefore concluded that the observed selectivities are a consequence of the facilitation of the departure of the leaving group by the solvent, from either side of the reaction center.
- Sinnott, Michael L.,Jencks, William P.
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p. 2026 - 2032
(2007/10/02)
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