- Synthesis of 2-iodoglycals, glycals, and 1,1′-disaccharides from 2-deoxy-2-iodopyranoses under dehydrative glycosylation conditions
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(Chemical Equation Presented) Treatment of 2-deoxy-2-iodopyranoses under dehydrative glycosylation conditions afforded pyranose glycals, 2-iodoglycals, and 1,1′-disaccharides instead of the expected glycoside products. While the product distribution revea
- Rodriguez, Miguel Angel,Boutureira, Omar,Matheu, M. Isabel,Diaz, Yolanda,Castillon, Sergio,Seeberger, Peter H.
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- Iterative Synthesis of 2-Deoxyoligosaccharides Enabled by Stereoselective Visible-Light-Promoted Glycosylation
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The photoinitiated intramolecular hydroetherification of alkenols has been used to form C?O bonds, but the intermolecular hydroetherification of alkenes with alcohols remains an unsolved challenge. We herein report the visible-light-promoted 2-deoxyglycosylation of alcohols with glycals. The glycosylation reaction was completed within 2 min in a high quantum yield (?=28.6). This method was suitable for a wide array of substrates and displayed good reaction yields and excellent stereoselectivity. The value of this protocol was further demonstrated by the iterative synthesis of 2-deoxyglycans with α-2-deoxyglycosidic linkages up to a 20-mer in length and digoxin with β-2-deoxyglycosidic linkages. Mechanistic studies indicated that this reaction involved a glycosyl radical cation intermediate and a photoinitiated chain process.
- Guo, Zhen-Yan,Liu, Kai-Meng,Liu, Meng,Liu, Miao,Qin, Xian-Jin,Wang, Peng-Yu,Xiong, De-Cai,Xue, Wan-Ying,Ye, Xin-Shan
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- Azomethine ylide cycloaddition of 2-C-formyl glycals with α-amino acids for the synthesis of substituted pyrroles
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A novel strategy has been devised for the synthesis of pyrrole based acyclo-C-nucleosides, in particular an open-chain sugar substituted pyrrole derivatives by means of the condensation of 2-C-formyl glycals with α-amino acids through an intramolecular azomethine cycloaddition under thermal conditions. The use of cyclic α-amino acids provides the corresponding bicyclic pyrrole derivatives. This is a first report on the synthesis of pyrrole based acyclo-C-nucleosides. 2009 Elsevier Ltd. All rights reserved.
- Reddy, B. V. Subba,Reddy, V. Veerabadhra
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- Light-Mediated Cross-Coupling of Anomeric Trifluoroborates
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Stereoselective reactions at the anomeric carbon constitute the cornerstone of preparative carbohydrate chemistry. Here, we report stereoselective C-arylation and etherification reactions of anomeric trifluoroborates derived from BMIDA esters. These react
- Miller, Eric M.,Walczak, Maciej A.
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p. 4289 - 4293
(2021/06/28)
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- Ir(I)-Catalyzed C?H Glycosylation for Synthesis of 2-Indolyl-C-Deoxyglycosides
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The construction of 2-deoxy-C-glycosides has gradually become a hotspot of carbohydrate chemistry in recent years. In this work, we present an efficient, regioselective, stereoselective and widely applicable strategy for the synthesis of 2-indolyl-C-deoxyglycosides via Ir(I)-catalyzed, pyridine-group-directed C?H functionalization. This method exhibits high tolerance for the functional groups of indoles and the protecting groups of carbohydrates. Moreover, this protocol has good stereoselectivity and mainly produces β-configuration products. Gram-scale synthesis and several practical transformations were conducted for further applications. Meantime, we also explored the mechanism of this method and proposed a catalytic cycle. (Figure presented.).
- Yu, Changyue,Liu, Yichu,Xie, Xiong,Hu, Shulei,Zhang, Shurui,Zeng, Mingjie,Zhang, Dan,Wang, Jiang,Liu, Hong
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supporting information
p. 4926 - 4931
(2021/09/09)
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- A protecting group-free approach for synthesizingC-glycosides through glycosyl dithiocarbamates
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The first protection/deprotection-free process for radicalC-glycosylation has been achieved through one-step preparable glycosyl dithiocarbamates (GDTCs). The Giese-type reaction and radical allylation of unprotected GDTCs were successfully performed to obtain the corresponding α-C-glycosides stereoselectively under mild reaction conditions.
- Li, Gefei,Noguchi, Masato,Arisaka, Genki,Tanaka, Yuuki,Shoda, Shin-Ichiro
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supporting information
p. 3134 - 3138
(2021/04/21)
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- Catalytic and Photochemical Strategies to Stabilized Radicals Based on Anomeric Nucleophiles
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Carbohydrates, one of the three primary macromolecules of living organisms, play significant roles in various biological processes such as intercellular communication, cell recognition, and immune activity. While the majority of established methods for the installation of carbohydrates through the anomeric carbon rely on nucleophilic displacement, anomeric radicals represent an attractive alternative because of their functional group compatibility and high anomeric selectivities. Herein, we demonstrate that anomeric nucleophiles such as C1 stannanes can be converted into anomeric radicals by merging Cu(I) catalysis with blue light irradiation to achieve highly stereoselective C(sp3)-S cross-coupling reactions. Mechanistic studies and DFT calculations revealed that the C-S bond-forming step occurs via the transfer of the anomeric radical directly to a sulfur electrophile bound to Cu(II) species. This pathway complements a radical chain observed for photochemical metal-free conditions where a disulfide initiator can be activated by a Lewis base additive. Both strategies utilize anomeric nucleophiles as efficient radical donors and achieve a switch from an ionic to a radical pathway. Taken together, the stability of glycosyl nucleophiles, a broad substrate scope, and high anomeric selectivities observed for the thermal and photochemical protocols make this novel C-S cross coupling a practical tool for late-stage glycodiversification of bioactive natural products and drug candidates.
- Chen, Zhenhao,Hong, Xin,Rui, Jinyan,Walczak, Maciej A.,Zhang, Shuo-Qing,Zhu, Feng
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supporting information
p. 11102 - 11113
(2020/07/13)
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- Esters of Glucose-2-Phosphate: Occurrence and Chemistry
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Phosphodiesters of glucose-2-phosphate (G2P) are found only in few natural compounds such as agrocinopine D and agrocin 84. Agrocinopine D is a G2P phosphodiester produced by plants infected by Agrobacterium fabrum C58 and recognized by the bacterial periplasmic binding protein AccA for being transported into the bacteria before cleavage by the phosphodiesterase AccF, releasing G2P, which promotes virulence by binding the repressor protein AccR. The G2P amide agrocin 84 is a natural antibiotic produced by the non-pathogenic Agrobacterium radiobacter K84 strain used as a biocontrol agent by competing with Agrobacterium fabrum C58. G2P esters are also found in irregular glycogen structures. The rare glucopyranosyl-2-phophoryl moiety found in agrocin 84 is the key structural signature enabling its action as a natural antibiotic. Likewise, G2P and G2P esters can also dupe the Agrobacterium agrocinopine catabolism cascade. Such observations illustrate the importance of G2P esters on which we have recently focused our interest. After a brief review of the reported phosphorylation coupling methods and the choice of carbohydrate building blocks used in G2P chemistry, a flexible access to glucose-2-phosphate esters using the phosphoramidite route is proposed.
- Ahmar, Mohammed,Li, Si-Zhe,Queneau, Yves,Soulère, Laurent,Zhang, Qiang
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- C-2 auxiliaries for stereoselective glycosylation based on common additive functional groups
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The stereoselective introduction of the glycosidic bond is one of the main challenges in chemical oligosaccharide synthesis. Stereoselective glycosylation can be achieved using neighbouring group participation of a C-2 auxiliary or using additives, for example. Both methods aim to generate a defined reactive intermediate that reacts in a stereoselective manner with alcohol nucleophiles. This inspired us to develop new C-2 auxiliaries based on commonly used additive functionalities such as ethers, phosphine oxides and tertiary amides. Good 1,2-trans-selectivity was observed for the phosphine oxide and amide-based auxiliaries expanding the toolbox with new auxiliaries for stereoselective glycosylation reactions.
- Boltje, Thomas J.,De Kleijne, Frank F. J.,Moons, Sam J.,White, Paul B.
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p. 1165 - 1184
(2020/02/22)
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- Total Synthesis of Tri-, Hexa- and Heptasaccharidic Substructures of the O-Polysaccharide of Providencia rustigianii O34
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A general and efficient strategy for synthesis of tri-, hexa- and heptasaccharidic substructures of the lipopolysaccharide of Providencia rustigianii O34 is described. For the heptasaccharide seven different building blocks were employed. Special features of the structures are an α-linked galactosamine and the two embedded α-fucose units, which are either branched at positions-3 and -4 or further linked at their 2-position. Convergent strategies focused on [4+3], [3+4], and [4+2+1] couplings. Whereas the [4+3] and [3+4] coupling strategies failed the [4+2+1] strategy was successful. As monosaccharidic building blocks trichloroacetimidates and phosphates were employed. Global deprotection of the fully protected structures was achieved by Birch reaction.
- Ahadi, Somayeh,Awan, Shahid I.,Werz, Daniel B.
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supporting information
(2020/05/04)
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- Carbonylative Negishi-Type Coupling of 2-Iodoglycals with Alkyl and Aryl Halides
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C-Glycosides are valuable organic compounds in the field of medicinal chemistry due to their ubiquity inside living systems and pronounced biological activity. Herein, we describe an approach to alkyl-ketones bearing glycal units via the Pd-catalyzed carb
- Esteves, Henrique A.,Darbem, Mariana P.,Pimenta, Daniel C.,Stefani, Hélio A.
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supporting information
p. 7384 - 7388
(2019/11/28)
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- α-Selective Glycosylation with β-Glycosyl Sulfonium Ions Prepared via Intramolecular Alkylation
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Stereoselective glycosylation remains the main challenge in the chemical synthesis of oligosaccharides. Herein we report a simple method to convert thioglycosides into β-sulfonium ions via an intramolecular alkylation reaction, leading to highly α-selective glycosylations for a variety of glycosyl acceptors. The influence of the thioglycoside substituent and the protecting group pattern on the glycosyl donor was investigated and showed a clear correlation with the observed stereoselectivity.
- Moons, Sam J.,Mensink, Rens A.,Bruekers, Jeroen P. J.,Vercammen, Maurits L. A.,Jansen, Laura M.,Boltje, Thomas J.
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p. 4486 - 4500
(2019/03/19)
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- Palladium-Catalyzed One-Pot Stereospecific Synthesis of 2-Deoxy Aryl C-Glycosides from Glycals and Anilines in the Presence of tert-Butyl Nitrite
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The palladium-catalyzed one-pot synthesis of 2,3-deoxy-3-keto aryl C-glycosides is achieved from glycals and anilines in the presence of tert-butyl nitrite and aqueous HBF 4 under mild conditions. This one-pot method stereospecifically provides α-and β-Aryl glycosides (≥19:1 by NMR) in good yields at room temperature. The configuration at the C-3 position in the glycal determines the anomeric selectivity (i.e., α or β) of the desired products.
- Kandasamy, Jeyakumar,Singh, Adesh Kumar,Venkatesh, Rapelly
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p. 4215 - 4230
(2019/11/14)
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- Sugar amino acids and oligosaccharide mimic prepared from sugar amino acids
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Belonging to the field of carbohydrate chemistry, the invention in particular relates to sugar amino acids and an oligosaccharide mimic prepared from the same. Cheap and easily available D-glucose andD-galactose are adopted as the starting raw materials for a series of reactions to obtain all-benzyl-protected glycal, the latter undergoes one-step free radical addition under the action of ceric ammonium nitrate (CAN) to obtain a precursor 2-C-nitro compound of SAAs, then Pd/C hydrogenation reaction for deprotection of Bn, reductive ammoniation and selective Boc protection reaction are carriedout to obtain a protected intermediate product of amino; then TIPSCl is utilized for selective protection of C-6 hydroxyl, then C-3 hydroxyl and C-4 hydroxyl are subjected to Bn protection, and deprotection of TIPS is carried out on C-6 hydroxyl; finally the C-6 hydroxyl is oxidized to obtain glucose-type and galactose-type SAAs blocks; and based on the obtained SAAs, a straight-chain type oligosaccharide mimic connected by an amido bond is synthesized, and condensation reaction is carried out to obtain 9 homologous and heterologous oligosaccharide mimics of straight-chain dimer, tetramer andoctamer. The method is simple, convenient, fast and effective.
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- Palladium catalyzed stereocontrolled synthesis of C-aryl glycosides using glycals and arenediazonium salts at room temperature
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A stereocontrolled synthesis of aryl-C-glycosides was achieved using glycals and aryldiazonium salts in the presence of palladium acetate. A wide range of glycals including d-glucal, d-galactal, l-rhamnal, d-xylal and d-ribal underwent C-arylation at the anomeric carbon in the presence of different aryldiazonium tetrafluoroborates and gave synthetically useful 2,3-deoxy-3-keto-α-aryl-C-glycosides in good to excellent yields. Broad substrate scope, simple operation and room temperature reactions make this protocol very attractive in organic synthesis.
- Singh, Adesh Kumar,Kandasamy, Jeyakumar
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supporting information
p. 5107 - 5112
(2018/07/29)
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- Diversity-Oriented Synthetic Endeavors of Newly Designed Ferrier and Ferrier-Nicholas Systems Derived from 1-C-Alkynyl-2-deoxy-2-C-Methylene Pyranosides
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Novel pyranose derivatives that display Ferrier- and Ferrier-Nicholas-like reactivity have been designed. These systems: 1-C-alkynyl-2-deoxy-2-C-methylene pyranosides (Ferrier), and their corresponding dicobalthexacarbonyl alkenyl derivatives (Ferrier-Nic
- Miranda, Silvia,Gómez, Ana M.,López, J. Cristóbal
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p. 5355 - 5374
(2018/09/10)
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- Synthesis of dibromo compounds containing 2,6-dioxabicyclo[3.1.1]heptane similar to core moiety of thromboxane A2
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Thromboxane A2, a potent platelet aggregation factor, contains a labile 2,6-dioxabicyclo[3.1.1]heptane as the core moiety. Dibromo compounds with a similar core structure were synthesized by the cyclization of tribromides derived from D-glucal.
- Nokura, Yoshihiko,Nakazaki, Atsuo,Nishikawa, Toshio
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p. 127 - 136
(2018/01/26)
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- TEMPO-Catalyzed Oxidation of 3- O-Benzylated/Silylated Glycals to the Corresponding Enones Using a PIFA-Water Reagent System
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A simple, highly efficient and regiospecific method for the direct conversion of 3-O-benzylated as well as silylated glycals into the corresponding enones has been developed using PIFA-TEMPO and water reagent system. The reaction is scalable on a gram sca
- Chennaiah, Ande,Verma, Ashish Kumar,Vankar, Yashwant D.
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p. 10535 - 10540
(2018/09/12)
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- Synthesis of Altrose Poly-amido-saccharides with β-N-(1→2)- d -amide Linkages: A Right-Handed Helical Conformation Engineered in at the Monomer Level
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The design and synthesis of amide-linked saccharide oligomers and polymers, which are predisposed to fold into specific ordered secondary structures, is of significant interest. Herein, right-handed helical poly amido-saccharides (PASs) with β-N-(1→2)-d-amide linkages are synthesized by the anionic ring-opening polymerization of an altrose β-lactam monomer (alt-lactam). The right-handed helical conformation is engineered into the polymers by preinstalling the β configuration of the lactam ring in the monomer via the stereospecific [2+2] cycloaddition of trichloroacetyl isocyanate with a d-glycal possessing a 3-benzyloxy group oriented to the α-face of the pyranose. The tert-butylacetyl chloride initiated polymerization of the alt-lactam proceeds smoothly to afford stereoregular polymers with narrow dispersities. Birch reduction of the benzylated polymers gives water-soluble altrose PASs (alt-PASs) in high yields without degradation of the polymer backbone. Circular dichroism analysis shows the alt-PASs adopt a right-handed helical conformation in aqueous solutions. This secondary conformation is stable over a wide range of different conditions, such as pH (2.0 to 12.0), temperature (5 to 75 °C), ionic salts (2.0 M LiCl, NaCl, and KCl), as well as in the presence of protein denaturants (4.0 M urea and guanidinium chloride). Cytotoxicity studies reveal that the alt-PASs are nontoxic to HEK, HeLa, and NIH3T3 cells. The results showcase the ability to direct solution conformation of polymers through monomer design. This approach is especially well-suited and straightforward for PASs as the helical conformations formed result from constraints imposed by the relatively rigid and sterically bulky repeating units.
- Xiao, Ruiqing,Dane, Eric L.,Zeng, Jialiu,McKnight, Christopher J.,Grinstaff, Mark W.
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p. 14217 - 14223
(2017/10/17)
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- Glycosyl Cross-Coupling of Anomeric Nucleophiles: Scope, Mechanism, and Applications in the Synthesis of Aryl C-Glycosides
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Stereoselective manipulations at the C1 anomeric position of saccharides are one of the central goals of preparative carbohydrate chemistry. Historically, the majority of reactions forming a bond with anomeric carbon has focused on reactions of nucleophiles with saccharide donors equipped with a leaving group. Here, we describe a novel approach to stereoselective synthesis of C-aryl glycosides capitalizing on the highly stereospecific reaction of anomeric nucleophiles. First, methods for the preparation of anomeric stannanes have been developed and optimized to afford both anomers of common saccharides in high anomeric selectivities. We established that oligosaccharide stannanes could be prepared from monosaccharide stannanes via O-glycosylation with Schmidt-type donors, glycal epoxides, or under dehydrative conditions with C1 alcohols. Second, we identified a general set of catalytic conditions with Pd2(dba)3 (2.5 mol%) and a bulky ligand (JackiePhos, 10 mol%) controlling the β-elimination pathway. We demonstrated that the glycosyl cross-coupling resulted in consistently high anomeric selectivities for both anomers with mono- and oligosaccharides, deoxysugars, saccharides with free hydroxyl groups, pyranose, and furanose substrates. The versatility of the glycosyl cross-coupling reaction was probed in the total synthesis of salmochelins (siderophores) and commercial anti-diabetic drugs (gliflozins). Combined experimental and computational studies revealed that the β-elimination pathway is suppressed for biphenyl-type ligands due to the shielding of Pd(II) by sterically demanding JackiePhos, whereas smaller ligands, which allow for the formation of a Pd-F complex, predominantly result in a glycal product. Similar steric effects account for the diminished rates of cross-couplings of 1,2-cis C1-stannanes with aryl halides. DFT calculations also revealed that the transmetalation occurs via a cyclic transition state with retention of configuration at the anomeric position. Taken together, facile access to both anomers of various glycoside nucleophiles, a broad reaction scope, and uniformly high transfer of anomeric configuration make the glycosyl cross-coupling reaction a practical tool for the synthesis of bioactive natural products, drug candidates, allowing for late-stage glycodiversification studies with small molecules and biologics.
- Zhu, Feng,Rodriguez, Jacob,Yang, Tianyi,Kevlishvili, Ilia,Miller, Eric,Yi, Duk,O'Neill, Sloane,Rourke, Michael J.,Liu, Peng,Walczak, Maciej A.
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supporting information
p. 17908 - 17922
(2017/12/26)
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- NOVEL ACETATES OF 2-DEOXY MONOSACCHARIDES WITH ANTICANCER ACTIVITY
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Novel compounds and methods of using the same to inhibit glycolysis and treat cancer and other diseases are provided herein.
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Paragraph 0073; 0074; 0075; 0076
(2017/04/01)
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- Highly Stereospecific Cross-Coupling Reactions of Anomeric Stannanes for the Synthesis of C-Aryl Glycosides
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We demonstrate that configurationally stable anomeric stannanes undergo a stereospecific cross-coupling reaction with aromatic halides in the presence of a palladium catalyst with exceptionally high levels of stereocontrol. In addition to a broad substrat
- Zhu, Feng,Rourke, Michael J.,Yang, Tianyi,Rodriguez, Jacob,Walczak, Maciej A.
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supporting information
p. 12049 - 12052
(2016/10/03)
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- TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals
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The thio-additions of glycals were efficiently promoted by a stoichiometric amount of trimethylsilyl bromide (TMSBr) to produce S-2-deoxyglycosides under solvent-free conditions in good to excellent yields. In addition, with triphenylphosphine oxide as an additive, the TMSBr-mediated direct glycosylations of glycals with a large range of alcohols were highly α-selective.
- Hsu, Mei-Yuan,Liu, Yi-Pei,Lam, Sarah,Lin, Su-Ching,Wang, Cheng-Chung
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supporting information
p. 1758 - 1764
(2016/10/05)
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- Direct C-H Trifluoromethylation of Glycals by Photoredox Catalysis
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A mild, efficient, and practical transformation for the direct C-H trifluoromethylation of glycals under visible light has been reported for the first time. This reaction employed fac-Ir3+(ppy)3 as the photocatalyst, Umemoto's reagent as the CF3 source, and a household blue LED or sunlight as the light source. Glycals bearing both electron-withdrawing and -donating protective groups performed this reaction smoothly. This visible light-mediated trifluoromethylation reaction was highlighted by the trifluoromethylation of the biologically important Neu2en moiety.
- Wang, Bang,Xiong, De-Cai,Ye, Xin-Shan
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p. 5698 - 5701
(2015/12/01)
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- Modular stereoselective synthesis of (1→2)-C-glycosides based on the sp2-sp3 Suzuki-Miyaura reaction
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This work reports a modular and rapid approach to the stereoselective synthesis of a variety of α- and β-(1→2)-linked C-disaccharides. The key step is a Ni-catalyzed cross-coupling reaction of D-glucal pinacol boronate with alkyl halide glycoside easily prepared from commercially available D-glucal. The products of this sp2-sp3 cross-coupling reaction can be converted to glucopyranosyl, mannopyranosyl, or 2-deoxy-glucopyranosyl C-mannopyranosides by one- or two-step stereoselective oxidative-reductive transformations. To the best of our knowledge, we demonstrated the first synthetic application of a challenging sp2-sp3 Suzuki-Miyaura cross-coupling reaction in carbohydrate chemistry.
- Oroszova, Beata,Choutka, Jan,Pohl, Radek,Parkan, Kamil
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supporting information
p. 7043 - 7047
(2015/05/05)
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- Iterative α-Glycosylation Strategy for 2-Deoxy- and 2,6-Dideoxysugars: Application to the One-Pot Synthesis of Deoxysugar-Containing Oligosaccharides
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This paper describes the development of an iterative and α-selective glycosylation method for 2-deoxyglycosyl and 2,6-dideoxythioglycoside donors based on the DMF modulation concept. We used NMR spectroscopy to probe the 2-deoxyglycosyl imidinium intermediate and elucidated the conditions to decrease the formation of glycal and thus to increase the reaction yields. Further elaboration of the glycosylation method opened the gate for an iterative one-pot synthesis of 2-deoxy- and 2,6-dideoxyglycoside-containing oligosaccharides. An iterative glycosylation method is established for highly reactive 2-deoxyglycosyl donors on the basis of the DMF modulation concept. This method is effective for 2-deoxy- and 2,6-dideoxythioglycosyl donors, and it opens the gate for the one-pot synthesis of deoxysugar-containing oligosaccharides; NIS = N-iodosuccinimide. Tf = trifluoromethylsulfonyl, NAP = 2-naphthylmethyl, STol = p-tolylthio, Bz = benzoyl.
- Chen, Jiun-Han,Ruei, Jyh-Herng,Mong, Kwok-Kong Tony
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p. 1827 - 1831
(2015/10/05)
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- Iterative α-glycosylation strategy for 2-deoxy- and 2,6-dideoxysugars: Application to the one-pot synthesis of deoxysugar-containing oligosaccharides
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This paper describes the development of an iterative and α-selective glycosylation method for 2-deoxyglycosyl and 2,6-dideoxythioglycoside donors based on the DMF modulation concept. We used NMR spectroscopy to probe the 2-deoxyglycosyl imidinium intermediate and elucidated the conditions to decrease the formation of glycal and thus to increase the reaction yields. Further elaboration of the glycosylation method opened the gate for an iterative one-pot synthesis of 2-deoxy- and 2,6-dideoxyglycoside-containing oligosaccharides
- Chen, Jiun-Han,Ruei, Jyh-Herng,Mong, Kwok-Kong Tony
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p. 1827 - 1831
(2014/04/03)
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- A substrate-based approach to skeletal diversity from dicobalt hexacarbonyl (C1)-alkynyl glycals by exploiting its combined ferrier-nicholas reactivity
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Novel substrates that combine dicobalt hexacarbonyl propargyl (Nicholas) and pyranose-derived allylic (Ferrier) cations have been generated by treatment of hexacarbonyldicobalt (C-1)-alkynyl glycals with BF3 .Et2O. The study of these cations has resulted in the discovery of novel reaction pathways that have shown to be associated to the nature of O-6 substituent in the starting alkynyl glycals. Accordingly, compounds resulting from ring expansion (oxepanes), ring contraction (tetrahydrofurans), or branched pyranoses, by incorporation of nucleophiles, can be obtained from 6-O-benzyl, 6-hydroxy, or 6-O-silyl derivatives, respectively. The use of a 6-O-allyl alkynyl glycal led to a suitable funtionalized oxepane able to experience an intramolecular Pauson-Khand cyclization leading to a single tricyclic derivative.
- Lobo, Fernando,Gomez, Ana M.,Miranda, Silvia,Lopez, J. Cristobal
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p. 10492 - 10502
(2014/08/18)
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- A concise synthesis of N-substituted fagomine derivatives and the systematic exploration of their α-glycosidase inhibition
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A novel and concise scheme has been developed successfully for the syntheses of N-substituted fagomine derivatives. The transformation of lactone (2) to 1,5-diol (3) was carried on with high yield (93-95%). The cyclization of 4 to 5 is a high stereoselect
- Jiang, Fu-Xiang,Liu, Qiao-Zhen,Zhao, Dan,Luo, Cui-Ting,Guo, Cui-Ping,Ye, Wen-Cai,Luo, Cheng,Chen, Heru
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p. 211 - 222
(2014/04/03)
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- A 3,4-trans-fused cyclic protecting group facilitates α-selective catalytic synthesis of 2-deoxyglycosides
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A practical approach has been developed to convert glucals and rhamnals into disaccharides or glycoconjugates with high α-selectivity and yields (77-97 %) using a trans-fused cyclic 3,4-O-disiloxane protecting group and TsOH·H2O (1 mol %) as a catalyst. Control of the anomeric selectivity arises from conformational locking of the intermediate oxacarbenium cation. Glucals outperform rhamnals because the C6 side-chain conformation augments the selectivity.
- Balmond, Edward I.,Benito-Alifonso, David,Coe, Diane M.,Alder, Roger W.,McGarrigle, Eoghan M.,Galan, M. Carmen
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supporting information
p. 8190 - 8194
(2014/08/18)
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- Divergent synthesis of 2-C-branched pyranosides and oxepines from 1,2-gem-dibromocyclopropyl carbohydrates
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The ring opening of 1,2-(gem-dibromo)cyclopropyl carbohydrates by two different modes leads to either 2-C-(bromomethylene)pyranosides (using base) or 2-bromooxepines (using silver salts), as shown previously by us for a D-glucal-derived cyclopropane. The base-promoted ring opening is extended to encompass additional alcohol, thiol and amine nucleophiles, and diastereoisomeric cyclopropane precursors. Cross-coupling of the 2-C-(bromomethylene)pyranosides leads to extended 2-C-branched pyranosides. Silver-promoted ring expansion of the cyclopropyl carbohydrates in the presence of various alcohols is described. Cross-coupling of the resulting benzyl 2-bromooxepines affords 2-C-substituted oxepines.
- Moore, Peter W.,Schuster, Julia K.,Hewitt, Russell J.,Stone, M. Rhia L.,Teesdale-Spittle, Paul H.,Harvey, Joanne E.
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supporting information
p. 7032 - 7043
(2015/02/19)
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- ESTERS OF 2-DEOXY-MONOSACCHARIDES WITH ANTI PROLIFERATIVE ACTIVITY
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Compounds and methods of using the same to inhibit glycolysis and treat cancer and other diseases are disclosed.
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Paragraph 0188-0190
(2014/10/18)
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- Application of the 2-nitrobenzyl group in glycosylation reactions: A valuable example of an arming participating group
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The application of the o-nitrobenzyl (oNBn) group is demonstrated. This practical methodology allows the stereocontrolled synthesis of glucosides with a 1,2-trans linkage. This new ether-type arming group can broadly extend the concept of the use of participating groups in glycosylation reactions. Easy protection and deprotection of the oNBn group further confirms its usefulness in synthesis. The application of o-nitrobenzyl (oNBn) ether as an arming participating group is demonstrated. This practical methodology allows the stereocontrolled synthesis of glucosides with a 1,2-trans linkage. Copyright
- Buda, Szymon,Golebiowska, Patrycja,Mlynarski, Jacek
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supporting information
p. 3988 - 3991
(2013/07/19)
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- D-Glucose and d-mannose-based metabolic probes. Part 3: Synthesis of specifically deuterated d-glucose, d-mannose, and 2-deoxy-d-glucose
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Altered carbohydrate metabolism in cancer cells was first noted by Otto Warburg more than 80 years ago. Upregulation of genes controlling the glycolytic pathway under normoxia, known as the Warburg effect, clearly differentiates malignant from non-maligna
- Fokt, Izabela,Skora, Stanislaw,Conrad, Charles,Madden, Timothy,Emmett, Mark,Priebe, Waldemar
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p. 111 - 119
(2013/03/28)
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- Design and synthesis of carbohydrate based medium sized sulfur containing benzannulated macrocycles: Applications of Sonogashira and Heck coupling
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Palladium catalyzed intramolecular Sonogashira and Heck coupling reactions have been applied for diversity-oriented synthesis of sulfur containing carbohydrate based medium sized ring macrocycles. The process involves design and synthesis of building bloc
- Hussain, Altaf,Yousuf, Syed Khalid,Sharma, Deepak K.,Mallikharjuna Rao,Singh, Baldev,Mukherjee, Debaraj
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supporting information
p. 5517 - 5524
(2013/07/05)
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- Fluorine-directed β-galactosylation: Chemical glycosylation development by molecular editing
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Validation of the 2-fluoro substituent as an inert steering group to control chemical glycosylation is presented. A molecular editing study has revealed that the exceptional levels of diastereocontrol in glycosylation processes by using 2-fluoro-3,4,6-tri-O-benzyl glucopyranosyl trichloroacetimidate (TCA) scaffolds are a consequence of the 2R,3S,4S stereotriad. This study has also revealed that epimerization at C4, results in a substantial enhancement in β-selectivity (up to β/α 300:1). Copyright
- Durantie, Estelle,Bucher, Christoph,Gilmour, Ryan
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p. 8208 - 8215
(2012/08/27)
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- N-heterocyclic carbene catalyzed C-glycosylation: A concise approach from stetter reaction
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Described herein is the first example of an organocatalytic approach for acylanion addition to the anomeric carbon of 2-nitroglucal using an N-heterocyclic carbene catalyst. Control over the reaction conditions gives β-selective and nitro-eliminated C-glycosides, providing opportunities to produce new classes of C-glycoside.
- Vedachalam, Seenuvasan,Tan, Shi Min,Teo, Hui Ping,Cai, Shuting,Liu, Xue-Wei
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p. 174 - 177
(2012/02/16)
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- Intramolecular base-free sonogashira reaction for the synthesis of benzannulated chiral macrocycles embedded in carbohydrate templates
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A base-free, intramolecular Sonogashira reaction-based general approach has been established for the diversity-oriented synthesis (DOS) of fused bi- and tricyclic systems containing benzannulated, 10- to 13-membered chiral macrocycles embedded in carbohydrate templates. Macrocycles with different ring sizes have been prepared by pre-designing the chiral building blocks. Base-sensitive groups like acetyl and TBDPS survived the reaction conditions. Copyright
- Hussain, Altaf,Yousuf, Syed Khalid,Kumar, Deepak,Lambu, Malikharjunarao,Singh, Baldev,Maity, Sudip,Mukherjee, Debaraj
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supporting information; experimental part
p. 1933 - 1940
(2012/09/22)
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- Stereoelectronic factors in the stereoselective epoxidation of glycals and 4-deoxypentenosides
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Glycals and 4-deoxypentenosides (4-DPs), unsaturated pyranosides with similar structures and reactivity profiles, can exhibit a high degree of stereoselectivity upon epoxidation with dimethyldioxirane (DMDO). In most cases, the glycals and their corresponding 4-DP isosteres share the same facioselectivity, implying that the pyran substituents are largely responsible for the stereodirecting effect. Fully substituted dihydropyrans are subject to a "majority rule", in which the epoxidation is directed toward the face opposite to two of the three groups. Removing one of the substituents has a variable effect on the epoxidation outcome, depending on its position and also on the relative stereochemistry of the remaining two groups. Overall, we observe that the greatest loss in facioselectivity for glycals and 4-DPs is caused by removal of the C3 oxygen, followed by the C5/anomeric substituent, and least of all by the C4/C2 oxygen. DFT calculations based on polarized-π frontier molecular orbital (PPFMO) theory support a stereoelectronic role for the oxygen substituents in 4-DP facioselectivity, but less clearly so in the case of glycals. We conclude that the anomeric oxygen in 4-DPs contributes toward a stereoelectronic bias in facioselectivity whereas the C5 alkoxymethyl in glycals imparts a steric bias, which at times can compete with the stereodirecting effects from the other oxygen substituents.
- Alberch, Laura,Cheng, Gang,Seo, Seung-Kee,Li, Xuehua,Boulineau, Fabien P.,Wei, Alexander
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p. 2532 - 2547
(2011/06/19)
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- SYNTHETIC OLIGOSACCHARIDES FOR MORAXELLA VACCINE
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The present invention provides synthetic Moraxella catarrhalis lipooligosaccharide (LOS)-based oligosaccharides and conjugates containing various M. catarrhalis serotype-specific oligosaccharide antigens or various core M. catarrhalis oligosaccharide structures or motifs corresponding to one or more of the three major serotypes and/or members within a given serotype. The oligosaccharides may be synthesized by a chemical assembly methodology relying on a limited number of monosaccharide and disaccharide building blocks. The invention further provides M. catarrhalis LOS-based immunogenic and immunoprotective compositions and antibodies derived therefrom for diagnosing, treating, and preventing infections caused by M. catarrhalis.
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Page/Page column 37-38
(2011/11/13)
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- Study of kaempferol glycoside as an insulin mimic reveals glycon to be the key active structure
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Diabetes mellitus is increasing in prevalence with patient numbers rising throughout the world. Current treatments for diabetes mellitus focus on control of blood glucose levels. Certain kinds of flavonoids or their glycosides stimulate cells to improve glucose uptake and lower blood glucose levels. We synthesized kaempferol 3-O-neohesperidoside (1), a naturally occurring substance present in Cyathea phalerata Mart., reported to mimic the action of insulin. Synthetic 1 promoted glucose uptake in the cultured cell line, L6. Further studies to determine the core structure responsible for this activity using synthetic compounds revealed neohesperidose to be the primary pharmacophore. These findings support the use of certain saccharides as a potential novel treatment for diabetes mellitus by replacing or supporting insulin.
- Yamasaki, Kazuaki,Hishiki, Ryogo,Kato, Eisuke,Kawabata, Jun
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supporting information; experimental part
p. 17 - 21
(2011/04/17)
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- A simple and convenient method for the synthesis of pyranoid glycals
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A simple, mild, and environmentally benign synthesis procedure of pyranoid glycals is described. In a novel fashion, protected glycopyranosyl bromides undergo the reductive elimination in the presence of zinc in phosphate buffer at room temperature. The pyranoid glycals were obtained in good-to-excellent yields (18 examples).
- Zhao, Jinzhong,Wei, Shanqiao,Ma, Xiaofeng,Shao, Huawu
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experimental part
p. 168 - 171
(2011/02/26)
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- Concise total syntheses of aspalathin and nothofagin
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Chemical Fig. Reprentation Syntheses of the C-glycosyl flavone natural products aspalathin and nothofagin have been accomplished in eight steps from tribenzyl glucal, tribenzylphloroglucinol, and either 4-(benzyloxy) phenylacetylene or 3,4-bis(benzyloxy)phenylacetylene. The key step of the syntheses involves a highly stereoselective Lewis acid promoted coupling of 1,2-di-o-acyl-3,4,6-tribenzylglucose with tribenzylphloroglucinol, which gives rise to the corresponding β-C-aryl glycoside in 30-65% yields.
- Yepremyan, Akop,Salehani, Baback,Minehan, Thomas G.
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supporting information; experimental part
p. 1580 - 1583
(2010/06/17)
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- Fluorine-directed glycosylation
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Everything's under control: A stabilizing fluorine electrostatic interaction has been exploited to control oxonium ion conformation in 2-fluoropyranose derivatives (see scheme). When matched with the inductive nature of the protecting groups, the glycosyl
- Bucher, Christoph,Gilmour, Ryan
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supporting information; experimental part
p. 8724 - 8728
(2011/01/06)
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- Synthesis of glycal-based chiral benzimidazoles by VO(acac) 2-CeCl3 combo catalyst and their self-aggregated nanostructured materials
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(Figure Presented) VO(acac)2-CeCl3 combo catalyst has been developed for chemoselective cyclocondensation cum oxidation under mild reaction conditions toward synthesis of a new class of optically pure compounds, 2-(2′-C-3′,4′,6′-tri-O-benzyl/methyl-glycal)-1H- benzimidazoles. It involves an operationally simple synthetic protocol efficient for the syntheses of a wide range of chiral benzimidazoles in high yields without formation of undesired 1,2-disubstituted and pseudoglycal byproducts. Vanadium(V) is found as active oxidant for the chemical processes which is investigated by UV absorption spectroscopy. Highly ordered one-dimensional low molecular mass organic nanostructured materials are fabricated by nanocrystallization of the chiral nanoscale building blocks. Theoretical calculation by the B3LYP/6-31G** level of theory of the glycal-based chiral benzimidazoles shows out of planar geometry of the 1H-anthra[1,2-d] imidazole-6,11-dione moiety, which is responsible for the strong self-aggregation to generate ultralong nanostructured materials. We have also found nice agreement between the theoretical results with the experimental observation in 2D-NOESY experiments. The photophysical property of the solid nanostructured materials is also reported. 2009 American Chemical Society.
- Maiti, Dilip K.,Halder, Samiran,Pandit, Palash,Chatterjee, Nirbhik,De Joarder, Dripta,Pramanik, Nabyendu,Saima, Yasmin,Patra, Amarendra,Maiti, Prabir K.
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supporting information; experimental part
p. 8086 - 8097
(2010/02/28)
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- Tandem epoxidation-alcoholysis or epoxidation-hydrolysis of glycals catalyzed by titanium(IV) isopropoxide or Venturello's phosphotungstate complex
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Venturello's phosphotungstate complex and titanium(IV) isopropoxide [Ti(O-i-Pr)4] were successfully used as catalysts for the epoxidation-alcoholysis of glycals using hydrogen peroxide [H2O 2]. Reaction substrates included a range of variously protected glycals and different alcohols were used as solvents. Ti(O-i-Pr)4 was only effective in methanol as solvent, but gave methyl glycosides in high yields and high selectivities. The Venturello complex proved to be a very versatile and efficient catalyst. Apart from epoxidation-alcoholysis in alcoholic solvents it also showed activity in biphasic conditions to allow for glycosylation of long-chain alcohols and was very effective in the stereoselective dihydroxylation of benzylated glucal.
- Levecque, Pieter,Gammon, David W.,Kinfe, Henok Hadgu,Jacobs, Pierre,De Vos, Dirk,Sels, Bert
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supporting information; experimental part
p. 1557 - 1568
(2009/07/10)
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- Diastereoselective Ni-catalyzed Negishi cross-coupling approach to saturated, fully oxygenated C-alkyl and C-aryl glycosides
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A Ni-catalyzed Negishi cross-coupling approach to C-glycosides is described with an emphasis on C-aryl glycosides. The combination of NiCl 2/PyBox in N,N′-dimethylimidazolidinone (DMI) enabled the synthesis of C-alkyl glycosides under mild reaction conditions. Moderate yields and β-selectivities were obtained for C-glucosides, and good yields and high α-selectivities were the norm for C-mannosides. For C-aryl glycosides, reactions employing Ni(COD)2/tBu-Terpy in N,N-dimethylformamide (DMF) were typically high yielding and provided C-glucosides with high β-selectivities (1:>10 α:β) and C-mannosides in moderate α-selectivities (3:1 α:β); α-C-aryl glycosides could be obtained by the combination of Ni(COD) 2/PyBox in DMF (>20:1 α:β). The collective studies suggest that stereochemical control of the C-glycosides is dependent on the substrate and catalysts combination. The Negishi protocol displays excellent functional group tolerance, as demonstrated by its use in the first total synthesis of the natural product salmochelin SX.
- Gong, Hegui,Gagne, Michel R.
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scheme or table
p. 12177 - 12183
(2009/02/05)
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- Generation of nitrile oxides under nanometer micelles built in neutral aqueous media: Synthesis of novel glycal-based chiral synthons and optically pure 2,8-dioxabicyclo[4.4.0]decene core
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(Chemical Equation Presented) A highly efficient strategy for chemoselective oxidation of aldoximes to nitrile oxides by iodosobenzene in neutral aqueous media is reported. Their in situ intermolecular 1,3-dipolar cycloaddition (1,3-DC) with olefins in nanometer aqueous micelles occurs with improved stereoselectivity and acceleration of reaction rate toward synthesis of new chiral synthons, 3-(2′-C-3′,4′,6′-tri-O- benzylglycal)-Δ2-isoxazolines and others. Construction of optically pure 2,8-dioxabicyclo[4.4.0]decene skeleta is performed by this green approach, and the stereochemistry of the new chiral center is predicted by B3LYP density functional theory.
- Chatterjee, Nirbhik,Pandit, Palash,Halder, Samiran,Patra, Amarendra,Maiti, Dilip K.
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p. 7775 - 7778
(2008/12/22)
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- Structural establishment of polygalatenosides A and B by total synthesis
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The first total synthesis of polygalatenosides A (1) and B (2), originally isolated from the traditional Chinese medicine and reported as antidepressant agents, is described here. Glycosylation between thiogalactosyl donors 6 and 7 and 1-deoxyglucosyl acc
- Huang, Chih-Ming,Liu, Rai-Shung,Wu, Tian-Shung,Cheng, Wei-Chieh
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p. 2895 - 2898
(2008/09/21)
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- A room temperature Negishi cross-coupling approach to C-alkyl glycosides
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Glycosyl halides serve as effective alkyl halides for room temperature Negishi cross-coupling reactions using functionalized alkyl zinc reagents. The catalyst for these reactions is in situ generated (PyBox)NiCl2. The functional group tolerance on the zinc reagent is typically high, and both benzyl and ester protecting groups on the carbohydrate are tolerated. Anomer selectivities are modest for glucosyl halides but high for mannosyl halides. Copyright
- Gong, Hegui,Sinisi, Riccardo,Gagne, Michel R.
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p. 1908 - 1909
(2007/10/03)
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