- A new catalyst for the reductive elimination of acylated glycosyl bromides to form glycals
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Ethylene-N,N′-bis(salicylideneiminato(IV)) {VO(salen)} was developed as a catalyst for the reductive elimination of acylated glycosyl bromides to form glycals. VO(salen) to be an effective catalyst for the preparation of glycals on a multi-gram scale. The catalyst was green in colour and changed to brown as the reaction progress.
- Stick, Robert V.,Stubbs, Keith A.,Tilbrook, D. Matthew G.,Watts, Andrew G.
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- Reactivity of per-O-acetylated 1-thioglycosides and glycosyl sulfones towards chromium(II) complexes in aqueous medium
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Anomeric carbon-sulfur bonds in 1-thioglycosides and glycosyl sulfones can be cleaved by chromium(II) complexes in water-DMF medium. Anomeric radicals as well as sugar-chromium(III) complex intermediates can be generated in these reactions, leading in some cases, to the exclusive formation of the corresponding glycals.
- Micskei, Károly,Juhász, Zsuzsa,Ratkovi?, Zoran R.,Somsák, László
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- A convenient and efficient synthesis of glycals by zinc nanoparticles
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A simple and efficient method for the synthesis of pyranoid glycals utilizing the reductive elimination of glycopyranosyl bromides by zinc nanoparticles in an acetate buffer is described. A variety of pyranoid glycals derivatives were obtained, especially for the synthesis of 6-deoxy-4,6-O-benzylidene and disaccharide glycals with good yields.
- Xu, Yun,Wang, Wenjun,Cai, Yu,Yang, Xia,Wang, Peng George,Zhao, Wei
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- A convenient synthesis of glycals employing in-situ generated Cp2TiCl
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Reductive elimination of acetylated glycosyl bromides to the corresponding glycal is easily achieved by mixing the bromide with Cp2TiCl2 and Mn in THF, and hence does not require the separate preparation of Cp2TiCl using glove-box techniques.
- Hansen, Thomas,Krintel, Sussie L.,Daasbjerg, Kim,Skrydstrup, Troels
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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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- Long-lived glycosyl-chromium(III) complex intermediates in aqueous medium. Preparation of pyranoid glycals
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Acetylated glycosyl-chromium(III)L (L=EDTA, NTA, IDA) complex intermediates (1) were detected in aqueous medium, with half-life-times of 30-300 minutes. The decay of these intermediates led to glycals (7-9) of high purity in preparatively usable 70-90% yields.
- Kovacs, Gyoengyver,Gyarmati, Julianna,Somsak, Laszlo,Micskei, Karoly
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- Controlled Living Cascade Polymerization to Make Fully Degradable Sugar-Based Polymers from d -Glucose and d -Galactose
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Monomers derived from glucose and galactose, which contain an endocyclic alkene (in the sugar ring) and a terminal alkyne, underwent a cascade polymerization to prepare new polymers with the ring-opened sugar incorporated into the polymer backbone. Polymerizations were well-controlled, as demonstrated by a linear increase in molecular weight with monomer-to-initiator ratio and generally narrow molecular weight dispersity values. The living nature of the polymerization was supported by the preparation of a block copolymer from two different sugar-based monomers. The resulting polymers were also fully degradable. They underwent fast and complete depolymerization to small molecules under acidic conditions.
- Bhaumik, Atanu,Peterson, Gregory I.,Kang, Cheol,Choi, Tae-Lim
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- Titanium(III) reagents in carbohydrate chemistry: Glycal and C-glycoside synthesis
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Titanocene(III) chloride and zirconcene(III) chloride are effective and mild reagents for radical generation in organic synthesis. In carbohydrate chemistry, these species are useful for the conversion of glycosyl halides to glycals, and for the stereospecific preparation of C-glycosides. In all cases, the 1-glycosyl radical is an active intermediate, generated by reaction of carbohydrate substrates with the organometallic. (C) 2000 Elsevier Science Ltd.
- Spencer, Roxanne P.,Schwartz, Jeffrey
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- Diastereoselective Synthesis of Thioglycosides via Pd-Catalyzed Allylic Rearrangement
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Stereoselective glycosylation is challenging in carbohydrate chemistry. Herein, stereoselective thioglycosylation of glycals via palladium-catalyzed allylic rearrangement yields various substituents on α-isomer thioglycosides. Two comprehensive series of aryl and benzyl thioglycosides were obtained via a combination of thiosulfates with glycals derived from glucose, arabinose, galactose, and rhamnose. Furthermore, diosgenyl α-l-rhamnoside and isoquercitrin achieved selectivity via stereospecific [2,3]-sigma rearrangements of α-sulfoxide-rhamnoside and α-sulfoxide-glucoside, respectively.
- Jiang, Xuefeng,Li, Jiagen,Wang, Ming
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supporting information
p. 9053 - 9057
(2021/11/30)
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- Method for efficiently constructing 1, 2-cis-2-nitro-glucoside and galactoside
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The invention discloses a method for efficiently constructing 1, 2-cis-2-nitro-glucoside and 1, 2-cis-2-nitro-galactoside, and belongs to the technical field of organic synthesis. According to the preparation method, the 1, 2-cis-2-nitro-glucoside and the 1, 2-cis-2-nitro-galactoside can be efficiently prepared through one-step synthesis. According to the present invention, the organic catalysis stereoselective glycosylation method is successfully applied to the sugar chemical total synthesis so that the problem of the construction of the 1, 2-cis-glucosidic bond between the most key sugar units is solved, and the foundation is established for the completion of the subsequent poly O-antigen total synthesis. The work has important reference value for related immunological research and vaccine development in the future.
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Paragraph 0038; 0062
(2021/08/11)
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- Preparation method of 3, 4, 6-O-triacetyl-D-glucal
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The invention relates to a preparation method of Tri-O-acetyl-D-glucal, which mainly solves the problems of volatile reagent, irritant smell, high cost and the like in the existing method. The technical scheme of the invention is as follows: the preparation method of 3, 4, 6-O-triacetyl-D-glucal comprises the following steps: peracetylated D-glucose is prepared by catalyzing D-glucose in glacial acetic acid with strong acid; the peracetylated D-glucose is brominated by a glacial acetic acid solution of hydrogen bromide to obtain brominated peracetylated D-glucose; and the brominated peracetylated D-glucose is reduced by zinc powder in an ammonium chloride solution to obtain a final product 3, 4, 6-O-triacetyl-D-glucal. The product provided by the invention has important application in thefields of glycopeptides and other polypeptide drugs.
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Paragraph 0012-0014
(2020/05/14)
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- The synthesis of rare earth metal-doped upconversion nanoparticles coated with d-glucose or 2-deoxy-d-glucose and their evaluation for diagnosis and therapy in cancer
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Rare earth metal-doped upconversion nanoparticles (UCNPs) are emerging as a new class of biomedical imaging materials due to their higher energy anti-Stokes shift, high optical penetration depth and long term repetitive imaging. In the present study, upconversion nanoparticles based on NaYF4 doped with thulium (Tm) and ytterbium (Yb) were prepared via a thermolysis method using oleic acid as a capping agent and 1-octadecene as a solvent. The X-ray diffraction pattern of the synthesized nanoparticles was found to match the standard hexagonal phase. The nanoparticles were coated with silica using tetraethyl orthosilicate (TEOS) and in order to avoid agglomeration, IGEPAL CO-520 was used as the surfactant. The coatings of SiO2 over NaYF4 were confirmed by the TEM image and XRD pattern. NaYF4@SiO2 was further functionalized by the addition of (3-aminopropyl)trimethoxysilane (APTMS) followed by either d-glucose or 2-deoxy-d-glucose (2-DG). UCNPs-d-glucose and UNCPs-2DG were examined for cell viability (MCF-7 cells) by MTT assay. The cellular uptake of UCNPs in MCF-7 cells was seen in terms of emission of a blue light. Furthermore, the uptake rate of UCNPs coated with 2-deoxy-d-glucose was found to be much faster than that of UCNPs alone under d-glucose starved conditions. The functionalization of UCNPs with 2-deoxy-d-glucose (2-DG) not only increased the uptake of nanoparticles, but also blocked the glycolysis pathway resulting in the inhibition of tumor growth as 2-deoxy-d-glucose (2-DG) is mimicking the d-glucose. The results are indicative that these upconversion nanoparticles may find applications in bio-imaging, removal of tumor by precision surgery, therapy and targeted drug delivery. This journal is
- Sharma, K. Shitaljit,Thoh, Maikho,Dubey, Akhil K.,Phadnis, Prasad P.,Sharma, Deepak,Sandur, Santosh K.,Vatsa, Rajesh K.
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p. 13834 - 13842
(2020/09/07)
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- Addressing the Structural Complexity of Fluorinated Glucose Analogues: Insight into Lipophilicities and Solvation Effects
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In this work, we synthesized all mono-, di-, and trifluorinated glucopyranose analogues at positions C-2, C-3, C-4, and C-6. This systematic investigation allowed us to perform direct comparison of 19F resonances of fluorinated glucose analogues and also to determine their lipophilicities. Compounds with a fluorine atom at C-6 are usually the most hydrophilic, whereas those with vicinal polyfluorinated motifs are the most lipophilic. Finally, the solvation energies of fluorinated glucose analogues were assessed for the first time by using density functional theory. This method allowed the log P prediction of fluoroglucose analogues, which was comparable to the C log P values obtained from various web-based programs.
- St-Gelais, Jacob,C?té, émilie,Lainé, Danny,Johnson, Paul A.,Giguère, Denis
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supporting information
p. 13499 - 13506
(2020/10/02)
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- Synthesis of 2′-paclitaxel 2-deoxy-2-fluoro-glucopyranosyl carbonate for specific targeted delivery to cancer cells
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A novel 2-fluorodeoxyglucose conjugated derivative of paclitaxel was efficiently synthesized using a linker between 2′-OH of paclitaxel and C1-hydroxyl group of 2-fluorodeoxyglucose. In preparation of the prodrug, allyl carbonates were selected as the protective group and the efficient one-step removal of allyloxycarbonyl groups at the end of the synthesis using palladium chemistry gave the target molecule in good yield. The prodrug not only improved the pharmaceutical properties of paclitaxel, such as solubility and stability, but also demonstrated enhanced cytotoxicity and selectivity for cancer cells and less toxicity toward normal HUVEC cells.
- Li, Tingshen,Li, Xiao,Lian, Xujing,Meng, Xin,Ya, Qiang,Yang, Yang,Zhang, Yan,Zhang, Yongmin
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supporting information
(2020/06/01)
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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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- Formation of five-membered carbocycles from D-glucose: A Concise Synthesis of 4-Hydroxy-2-(hydroxymethyl)cyclopentenone
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A concise synthesis of 4-hydroxy-2-(hydroxymethyl)cyclo-pentenone (1) has been accomplished from D-glucose by a three-step sequence that features a catalyst-free hydrothermal reaction of D-glucal, which is readily obtained from D-glucose. Optimization of the reaction conditions for synthesizing 1 was performed by changing the temperature and reaction time. The treatment of D-glucal under the optimal conditions, i.e., at 120 °C for 24 h, provided 1 in the highest isolated yield of 61%. 1 would become a versatile intermediate for the synthesis of various fine chemicals having a cyclopentenone structure from cellulosic biomass.
- Koseki, Yoshitaka,Watanabe, Toshihiro,Kamishima, Takaaki,Kwon, Eunsang,Kasai, Hitoshi
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p. 1324 - 1328
(2019/09/18)
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- Fluoroglycosyl-modified paclitaxel compound and synthesis method and application thereof
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The invention relates to a fluoroglycosyl-modified paclitaxel compound represented by the following structural general formula described in the invention. The paclitaxel compound can be hydrolyzed slowly to release paclitaxel drugs. In-vitro cytotoxicity experiment studies find out that the paclitaxel compound has the same tumor cell killing effect as that of paclitaxel, can be applied in improvement of the water solubility of the paclitaxel compound, and also can be applied in preparation of drugs for treatment or prevention of malignant tumors.
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Paragraph 0138; 0141; 0142
(2019/07/29)
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- Gastrodin compound, and preparation method and application thereof (by machine translation)
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The invention provides gastrodin compounds, as shown in a formula (I) as shown in a formula (II). Compared with the prior art, the gastrodin compound provided by the invention has a good analgesic effect and a simple preparation method, and can be applied to registration, quality research, process research and control page, and can also be used as a pharmaceutical ingredient alone or in combination with other components for drug development. (by machine translation)
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Paragraph 0057-0059
(2019/08/01)
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- Preparation method of 6-bromo-D-glucal
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The invention discloses a preparation method of 6-bromo-D-glucal. The reaction route is as follows. The preparation method comprises the following steps: (1), taking glucose as an initial material, and performing reaction in a sodium acetate/acetic anhydride system, so as to form a compound 1; (2), ensuring that the compound 1 is reacted with hydrobromic acid in acetic acid in a methylene dichloride system, so as to form a compound 2; (3), ensuring that the compound 2 is reacted with zinc powder in an acetone/saturated sodium dihydrogen phosphate, so as to form a compound 3; (4), ensuring thatthe compound 3 is reacted in a methanol/sodium methylate system, so as to form D-glucal, and then ensuring that the compound 3 is sequentially reacted with TsCl and acetic anhydride in a pyridine/methylene dichloride system, so as to form a compound 4; (5), ensuring that the compound 4 is reacted with LiBr in a DMSO system, so as to form a compound 5; (6), ensuring that the compound 5 is reacteda the sodium methylate/methanol system, so as to form a compound 6. The preparation method is simple to operate, mild in reaction conditions, cheap and available in raw materials, high in yield, low in cost, and suitable for mass industrial production.
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Paragraph 0033; 0034; 0035; 0036
(2019/02/26)
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- Stereocontrolled Synthesis of Highly Substituted trans α,β-Unsaturated Ketones with Potent Anticancer Properties from Glycals
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A novel synthetic route for highly substituted conjugated ketones has been developed utilizing glycals as starting materials. The two-step process combined the Heck reaction/Lewis acid promoted ring opening to afford the products in 33–80 % overall yields and with a high level of trans stereoselectivity. Since the products are essentially the aldols, this methodology may be employed in some cases as an alternative synthetic route to the typical aldol condensation. Densely substituted, selectively protected conjugated ketones are synthetically attractive structures which, in our case, proved to be biologically equally appealing. Namely, they showed activity against several cancer cell lines, such as HeLa, K562, MDA-MB-453, in some instances overperforming cisplatin used as a standard.
- Jovanovic, Predrag,Petkovic, Milos,Simic, Milena,Jovanovic, Milos,Tasic, Gordana,Crnogorac, Marija Djordjic,Zizak, Zeljko,Savic, Vladimir
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p. 4701 - 4709
(2019/07/31)
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- A Highly Efficient Magnetic Iron(III) Nanocatalyst for Ferrier Rearrangements
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A novel and highly efficient magnetic Fe 3 O 4 &at;C&at;Fe(III) core-shell catalyst, in which the carbon shell was prepared from lotus leaf, was fabricated. This nanocatalyst was successfully applied in the synthesis of a series of 2,3-unsaturated O- glycosides in excellent yields and with high selectivity, especially in the case of 2-halo O- glycosides, which differ in reactivity from nonsubstituted O- glycosides, but which have scarcely been explored before. Moreover, the catalyst could be easily separated from the reaction by the application of an external magnetic force and reused a minimum of five times without any significant decrease in the yields of the products. In addition, the reaction proceeded readily on a gram scale, which provides a bright prospect for future applications.
- Chen, Heshan,Ding, Zekun,Dong, Youxian,Guo, Hong,Jiang, Nan,Qiu, Saifeng,Xu, Xiaoxia,Zhang, Jianbo,Zhou, Le
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supporting information
p. 1419 - 1426
(2019/07/15)
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- Total Synthesis of a Densely Functionalized Plesiomonas shigelloides Serotype 51 Aminoglycoside Trisaccharide Antigen
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Plesiomonas shigelloides, a pathogen responsible for frequent outbreaks of severe travelers' diarrhea, causes grave extraintestinal infections. Sepsis and meningitis due to P. shigelloides are associated with a high mortality rate as antibiotic resistance increases and vaccines are not available. Carbohydrate antigens expressed by pathogens are often structurally unique and are targets for developing vaccines and diagnostics. Here, we report a total synthesis of the highly functionalized trisaccharide repeating unit 2 from P. shigelloides serotype 51 from three monosaccharides. A judicious choice of building blocks and reaction conditions allowed for the four amino groups adorning the sugar rings to be installed with two N-acetyl (Ac) groups, rare acetamidino (Am), and d-3-hydroxybutyryl (Hb) groups. The strategy for the differentiation of amino groups in trisaccharide 2 will serve well for the syntheses of other complex glycans.
- Qin, Chunjun,Schumann, Benjamin,Zou, Xiaopeng,Pereira, Claney L.,Tian, Guangzong,Hu, Jing,Seeberger, Peter H.,Yin, Jian
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supporting information
p. 3120 - 3127
(2018/03/08)
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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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Paragraph 0052; 0054; 0057
(2018/10/04)
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- Facile Approaches to 2-Deoxy- d -glucose and 2-Deoxy-α- d -glucopyranonucleosides from d -Glucal
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Convenient and stereoselective methods for the preparation of 2-deoxy- d -glucose and purine 2-deoxy-α- d -glucopyranonucleosides were developed. Halogen-mediated O-glycosidation of d -glucal by bromine in MeOH followed by reductive removal of the halo group and hydrolysis of methoxy group by zinc in saturated aqueous sodium dihydrogen phosphate gave 2-deoxy- d -glucose. Treatment of 3,4,6-tri- O -acetyl- d -glucal with IBr and 2,6-dichloropurine based on haloetherification and subsequent reductive removal of iodine and deprotection allowed the isolation of purin-9-yl 2-deoxy-α- d -glucopyranonucleoside. Preparation of several purin-9-yl 2-deoxy-α- d -glucopyranoside derivatives is also reported. Their configuration was confirmed by single crystal X-ray analysis of the key intermediate 2,6-dichloro-9-(2-iodo-2-deoxy-α- d -glucopyranosyl)purine.
- Xu, Wenke,Yang, Hui,Liu, Yingju,Hua, Yingchun,He, Bin,Ning, Xin,Qin, Zhiyan,Liu, Hong-Min,Liu, Feng-Wu
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supporting information
p. 3686 - 3691
(2017/08/16)
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- Preparation method of glycal
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The invention belongs to the technical field of chemical engineering and discloses a preparation method of glycal. The method comprises the following steps: (1) adding an organic solvent into a reactor equipped with polyhydroxyaldehyde monosaccharide and a catalyst in an atmosphere of nitrogen, adding a hydroxyl protective agent, carrying out a reflux reaction, and carrying out subsequent processing to obtain a compound a; (2) successively adding ammonium salt and an organic solvent into the compound a under the condition of nitrogen so as to carry out a reaction, and carrying out subsequent processing to obtain a compound b; (3) letting the compound b, substituted hydrazine and a water-removal additive into an organic solvent under the condition of nitrogen so as to carry out a reaction, and carrying out subsequent processing to obtain a compound c; and (4) adding a catalyst and the compound c dissolved in the organic solvent into alkali under the condition of nitrogen, reacting, and carrying out subsequent processing so as to obtain glycal. The preparation method is simple and easy to operate, is low-cost and environment-friendly, and has market advantages. Meanwhile, yield of glycal prepared by the preparation method is good.
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Paragraph 0044; 0075; 0076
(2017/07/21)
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- Site-Selective, Copper-Mediated O-Arylation of Carbohydrate Derivatives
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Site-selective functionalization of hydroxy groups in sugar derivatives is a major challenge in carbohydrate synthesis. Methods for achieving this goal will provide efficient access to new sugar-derived chemical building blocks and will facilitate the preparation or late-stage modification of complex oligosaccharides for applications in glycobiology research and drug discovery. Here, we describe site-selective, copper-promoted couplings of boronic acids with carbohydrate derivatives. These reactions generate sugar-derived aryl ethers, a structural class that is challenging to generate by other means and has not previously been accessed in a site-selective fashion. Experimental evidence and computational modeling suggest that the formation of a sugar-derived boronic ester intermediate is crucial to the selectivity of these processes, accelerating the arylation of an adjacent hydroxy group. The results demonstrate how the interactions of sugars with boron compounds can be combined with transition metal catalysis to achieve new chemical reactivity.
- Dimakos, Victoria,Garrett, Graham E.,Taylor, Mark S.
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supporting information
p. 15515 - 15521
(2017/11/06)
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- Synthesis of Aryl C-Glycosides via Iron-Catalyzed Cross Coupling of Halosugars: Stereoselective Anomeric Arylation of Glycosyl Radicals
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We have developed a novel diastereoselective iron-catalyzed cross-coupling reaction of various glycosyl halides with aryl metal reagents for the efficient synthesis of aryl C-glycosides, which are of significant pharmaceutical interest due to their biological activities and resistance toward metabolic degradation. A variety of aryl, heteroaryl, and vinyl metal reagents can be cross-coupled with glycosyl halides in high yields in the presence of a well-defined iron complex, composed of iron(II) chloride and a bulky bisphosphine ligand, TMS-SciOPP. The chemoselective nature of the reaction allows the use of synthetically versatile acetyl-protected glycosyl donors and the incorporation of various functional groups on the aryl moieties, producing a diverse array of aryl C-glycosides, including Canagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), and a prevailing diabetes drug. The cross-coupling reaction proceeds via generation and stereoselective trapping of glycosyl radical intermediates, representing a rare example of highly stereoselective carbon-carbon bond formation based on iron catalysis. Radical probe experiments using 3,4,6-tri-O-acetyl-2-O-allyl-α-d-glucopyranosyl bromide (8) and 6-bromo-1-hexene (10) confirm the generation and intermediacy of the corresponding glycosyl radicals. Density functional theory (DFT) calculations reveal that the observed anomeric diastereoselectivity is attributable to the relative stability of the conformers of glycosyl radical intermediates. The present cross-coupling reaction demonstrates the potential of iron-catalyzed stereo- and chemoselective carbon-carbon bond formation in the synthesis of bioactive compounds of certain structural complexity.
- Adak, Laksmikanta,Kawamura, Shintaro,Toma, Gabriel,Takenaka, Toshio,Isozaki, Katsuhiro,Takaya, Hikaru,Orita, Akihiro,Li, Ho C.,Shing, Tony K. M.,Nakamura, Masaharu
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supporting information
p. 10693 - 10701
(2017/08/15)
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- General Approach to Five-Membered Nitrogen Heteroaryl C-Glycosides Using a Palladium/Copper Cocatalyzed C-H Functionalization Strategy
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A general approach to the synthesis of diverse heteroaryl-C-Δ1,2-glycosides has been developed by employing the Pd(OAc)2/CuI cocatalyzed direct cross-coupling of five-membered nitrogen heterocycles with 1-iodoglycals in a C-H activation manner. Using this method, 27 examples of heteroaryl-C-Δ1,2-glycosides, containing indoles, thiazoles, benzothiazoles, imidazoles, benzimidazoles, and benzoxazoles as aglycones were obtained in 43-99% yield.
- Zhang, Shuo,Niu, You-Hong,Ye, Xin-Shan
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supporting information
p. 3608 - 3611
(2017/07/15)
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- Substrate-Controlled Diastereoselective Synthesis of Sugar-Based Chlorinated Perhydrofuro[2,3-b]pyrans via Copper(I)-Catalyzed Radical Cyclization
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The work describes the first copper(I) chloride/2,2′-bipyridine-catalyzed atom transfer radical cyclization (ATRC) of unsaturated carbohydrate-derived chloroacetals to generate chlorinated perhydrofuro[2,3-b]pyrans via an effective diastereoselective route. Various glycals (glucal, galactal and lactal) underwent the Ferrier rearrangement with 2,2,2-trichloroethanols to give acetal precursors stereoselectively, R-selective with galactal in contrast to S-selective with glucal. The radical cyclization of the Ferrier products occurred smoothly to afford cis-fused bicyclic products with the transfer of the chlorine atom at the non-anomeric carbon in the cyclized radical intermediate predominantly from the equatorial direction. The carbohydrate templates controlled the stereochemistry of both Ferrier rearrangement and ATRC steps. The stereostructures of the products were also supported by single crystal X-ray diffraction crystallography. The products possess biologically important structural segments such as a glycosidic linkage, a fused bicyclic acetal unit and a chlorosugar unit which are potential sources for biological studies and further synthetic elaborations. (Figure presented.).
- Ram, Ram N.,Kumar, Neeraj,Gupta, Dharmendra Kumar
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p. 432 - 442
(2017/02/10)
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- Bisindolyl maleimide derivative and preparation method and application thereof
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The invention provides a bisindolyl maleimide derivative and a preparation method and application thereof. The bisindolyl maleimide derivative has an excellent alpha-glucosidase inhibition effect and can be used for preventing and treating diabetes.
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Paragraph 0752
(2017/01/02)
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- Bisindolylmaleimide derivative, and preparation method and use thereof
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The invention provides a bisindolylmaleimide derivative, and a preparation method and a use thereof. The bisindolylmaleimide derivative has a good tumor treatment effect, especially has a good treatment effect on some drug-resistant tumors, and can realize accurate treatment of the drug-resistant tumors.
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Paragraph 0754; 0755
(2017/04/03)
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- An efficient method for the synthesis of pyranoid glycals
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A simple and efficient procedure was designed for the preparation of pyranoid glycals. In a novel fashion, a series of protected glycopyranosyl bromides underwent reductive elimination in the presence of zinc dust and ammonium chloride in CH3CN at 30-60 °C. The corresponding glycals were obtained with excellent isolated yields (72-96%) in a short time (20-50 min). Furthermore, the transformation was compatible with different protection patterns and conveniently scalable (86% for 45 g acetobromoglucose) which made it very applicable in organic synthesis.
- Chen, Heshan,Xian, Ting,Zhang, Wan,Si, Wenshuai,Luo, Xiaosheng,Zhang, Bo,Zhang, Meiyu,Wang, Zhongfu,Zhang, Jianbo
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supporting information
p. 42 - 46
(2016/07/06)
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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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- An efficient method for the synthesis of some chlorinated and heteroatom rich triazole-linked β-lactam glycoconjugates
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The synthetic utility of chlorinated bicyclic C-fused tetrahydrofuro[3,2-c] azetidin-2-ones synthesized in our laboratory by Cu(I)-catalyzed halogen atom transfer radical cyclization (ATRC) has been illustrated through the synthesis of some novel β-lactam glycoconjugates. The chlorine atom of the chloromethyl side chain of the bicyclic C-fused tetrahydrofuro[3,2-c] azetidin-2-ones was subjected to nucleophilic substitution with azide group followed by Cu(I)-catalyzed azide-alkyne click reaction (CuAAC) with propargyl glycosides to generate the desirous β-lactam glycoconjugates. A sequential optimization of the reaction procedure for CuAAC was carried out to obtain an efficient catalyst system to achieve β-lactam glycoconjugates in good yields. The β-lactam glycoconjugates are the compounds of interesting architecture and structurally suitable for bioactivity evaluation. Therefore, these β-lactam glycoconjugates were screened for in vitro antibacterial activity. Additionally, a representative β-lactam glycoconjugate was also tested for biocompatibility and cytotoxic activity against L929 cancer cell lines.
- Dawra, Nisha,Ram, Ram N.
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supporting information
p. 7982 - 7991
(2016/11/19)
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- Stereoselective synthesis and antitumoral activity of: Z -enyne pseudoglycosides
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An efficient approach for the synthesis of Z-1,3-enynes based on the coupling reaction of Z-vinyl tellurides and alkynes containing a pseudoglycoside moiety is described. The products were obtained in good yields via a stereoselective way. Preliminary screening against three tumor cell lines indicated that the synthesized compounds are promising intermediates for the synthesis of an array of more potent target structures.
- Dantas, Claudio R.,De Freitas, Jucleiton J. R.,Barbosa, Queila P. S.,Milit?o, Gardenia C. G.,Silva, Thiago D. S.,Da Silva, Teresinha G.,Paulino, Ant?nio A. S.,Freitas, Juliano C. R.,Oliveira, Roberta A.,Menezes, Paulo H.
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p. 6786 - 6794
(2016/07/21)
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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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supporting information
p. 5698 - 5701
(2015/12/01)
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- "Armed and disarmed" theory in the addition of an azide radical to glucals
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In this report, "armed and disarmed" theory was used to explain the selectivity of azide radical addition to glucals. We discovered that "armed" glucals were prone to undergo a kinetic process. The torsional strains govern the selectivity. Meanwhile, "disarmed" glucals preferred thermodynamic radical addition. We also applied our method to synthesize a sialic acid containing trisaccharide.
- Wang, Wenjun,Yang, Zhongyue,Xu, Yun,Liu, Taibao,Song, Tianbang,Zhao, Yunyan,Xu, Xiufang,Zhao, Wei,Wang, Peng George
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p. 38577 - 38580
(2015/07/07)
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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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- NaBH3CN: A janus substitute for tin-free radical-based reactions
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Beside showing that thermal radical reactions (reduction, Giese reaction) are efficient if bromo-/iodosugars are treated with NaBH3CN and 2,2″-azobisisobutyronitrile, we explored new initiation conditions on the basis of CuI salts (≤0.5 equiv.) supposed to produce radicals from organobromides through a set. This was confirmed, as at about 50 C under an inert atmosphere acetobromoglucose was reduced to the rearranged 2-deoxyglucose and as N-allyl α-bromoamides reacted, depending on the conditions, either by reductive cyclization or atom-transfer radical cyclization. A related cyclization occurred upon using Cu(OAc)2. This and other assays showed the reduction by NaBH3CN of CuII salts, either added or formed in situ. Having both ionic and radical reactivity, NaBH 3CN appears as a Janus reagent that may be useful for tin-free radical chemistry under mild and very simple conditions. Copyright
- Guiard, Julie,Rahali, Yaniss,Praly, Jean-Pierre
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supporting information
p. 4461 - 4466
(2014/08/05)
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- Pd-catalyzed allylic alkylation cascade with dihydropyrans: Regioselective synthesis of furo[3,2- c ]pyrans
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A regioselective palladium-catalyzed allylic alkylation cascade forms furo[3,2-c]pyrans from various cyclic β-dicarbonyl bis-nucleophiles and 3,6-dihydro-2H-pyran bis-electrophiles. The combination of allylic carbonate and anomeric siloxy leaving groups in the dihydropyran substrate allows control of the many regiochemical possibilities in this reaction. Annulation proceeds stereoconvergently to give cis-fused furopyrans from either cis- or trans-substituted starting material.
- Bartlett, Mark J.,Turner, Claire A.,Harvey, Joanne E.
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supporting information
p. 2430 - 2433
(2013/07/05)
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- Stereoselective synthesis of β-glycosyl thiols and their synthetic applications
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A significantly fast reaction condition for the exclusive preparation β-glycosyl thiol derivatives has been developed successfully. The reaction condition is one-step, fast, high yielding, highly stereoselective, and requires only benchtop chemicals. Further reaction of glycosyl thiol derivatives with Michael acceptors and alkylating agents furnished thioglycosides and (1,1)-thiolinked trehalose analogs.
- Jana, Manas,Misra, Anup Kumar
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p. 2680 - 2686
(2013/04/24)
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- PROCESS FOR PREPARING HEPARINOIDS AND INTERMEDIATES USEFUL IN THE SYNTHESIS THEREOF
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Processes are disclosed for the synthesis of the Factor Xa anticoagulant fondaparinux and related compounds. Protected pentasaccharide intermediates and efficient and scalable processes for the industrial scale production of fondaparinux sodium by conversion of the protected pentasaccharide intermediates via a sequence of deprotection and sulfonation reactions are provided.
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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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supporting information; experimental part
p. 174 - 177
(2012/02/16)
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- Stereoselective synthesis of pseudoglycosides catalyzed by TeCl4 under mild conditions
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Catalytic amounts of tellurium(IV) tetrachloride were used to promote the O-glycosylation of 3,4,6-tri-O-acetyl-d-glucal to give the corresponding 2,3-unsaturated-O-glycosides. With simple alcohols, the desired compounds were obtained in good yields and excellent anomeric selectivity in a short reaction time using only 2 mol % of the catalyst. The application of the method in the synthesis of a small set of glycopyranosides with rigid or flexible linkers gave the corresponding α anomers as products in good yields. Further applications of some of the synthesized compounds in allylation reaction of aldehydes gave the corresponding homoallylic alcohols in good yields.
- Freitas, Juliano C. R.,Couto, Tulio R.,Paulino, Antonio A. S.,Malvestiti, Ivani,Oliveira, Roberta A.,Menezes, Paulo H.,De Freitas Filho, Joao R.
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p. 10611 - 10620,10
(2012/12/12)
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- The synthesis of a 2-deoxy-2-acetonyl sugar from its corresponding natural saccharide
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An efficient synthesis of a 2-deoxy-2-acetonyl sugar from its corresponding natural sugar by methallylation of the 2-iodo sugar is reported. The simplified procedure eliminated the need to carry out the reaction under strictly controlled conditions, giving an efficient route for the synthesis of 2-deoxy-2-acetonyl sugar under ordinary laboratory conditions.
- Zhang, Ying,Liu, Yang,Wang, Zhijun,Wang, Zhongfu,Huang, Linjuan
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p. 244 - 246
(2012/09/08)
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- Diastereoselective metal-catalyzed synthesis of C-aryl and C-vinyl glycosides
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Cobalt, the catalyst of choice: The diastereoselective cobalt-catalyzed cross-coupling of 1-bromo glycosides and aryl or vinyl Grignard reagents is described. A convenient and inexpensive catalyst, [Co(acac)3]/tmeda (acac=acetylacetonate, tmeda=N,N'-tetramethylethylenediamine), gives full α selectivity in the mannose and galactose series, and an α selectivity in the glucose series with α/β ratios of 1.3:1-3:1. Copyright
- Nicolas, Lionel,Reymond, Sebastien,Cossy, Janine,Angibaud, Patrick,Stansfield, Ian,Bonnet, Pascal,Meerpoel, Lieven
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supporting information
p. 11101 - 11104,4
(2012/12/12)
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- Diastereoselective metal-catalyzed synthesis of C-aryl and C-vinyl glycosides
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Cobalt, the catalyst of choice: The diastereoselective cobalt-catalyzed cross-coupling of 1-bromo glycosides and aryl or vinyl Grignard reagents is described. A convenient and inexpensive catalyst, [Co(acac)3]/tmeda (acac=acetylacetonate, tmeda=N,N'-tetramethylethylenediamine), gives full α selectivity in the mannose and galactose series, and an α selectivity in the glucose series with α/β ratios of 1.3:1-3:1. Copyright
- Nicolas, Lionel,Angibaud, Patrick,Stansfield, Ian,Bonnet, Pascal,Meerpoel, Lieven,Reymond, Sébastien,Cossy, Janine
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supporting information
p. 11101 - 11104
(2013/01/15)
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- Stereoselective synthesis of pseudoglycosides catalyzed by TeCl4 under mild conditions
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Catalytic amounts of tellurium(IV) tetrachloride were used to promote the O-glycosylation of 3,4,6-tri-O-acetyl-d-glucal to give the corresponding 2,3-unsaturated-O-glycosides. With simple alcohols, the desired compounds were obtained in good yields and excellent anomeric selectivity in a short reaction time using only 2 mol % of the catalyst. The application of the method in the synthesis of a small set of glycopyranosides with rigid or flexible linkers gave the corresponding α anomers as products in good yields. Further applications of some of the synthesized compounds in allylation reaction of aldehydes gave the corresponding homoallylic alcohols in good yields.
- Freitas, Juliano C.R.,Couto, Túlio R.,Paulino, Ant?nio A.S.,De Freitas Filho, Jo?o R.,Malvestiti, Ivani,Oliveira, Roberta A.,Menezes, Paulo H.
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p. 8645 - 8654
(2012/10/29)
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- A rapid synthesis of pyranoid glycals promoted by β-cyclodextrin and ultrasound
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A convenient and environmentally benign procedure for the synthesis of glycals from glycosyl bromides with very low zinc dust loading (1.5 equiv.) is described. The process is activated by β-cyclodextrin and ultrasound. Based on 19 samples, this method has been demonstrated to be highly effective for a broad range of glycosyl bromides, including acid- or base-sensitive and disaccharide glycosyl bromides. A yield of 85%-96% of glycals was obtained. Copyright
- Zhao, Jinzhong,Shao, Huawu,Wu, Xin,Shi, Shaojing
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experimental part
p. 1434 - 1440
(2011/11/05)
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- Oxidative addition of secondary C-X bonds to palladium(0): A beneficial anomeric acceleration
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The oxidative addition of secondary electrophiles to Pd(0) is significantly accelerated by anomeric effects. In contrast to cyclohexyl bromide, acetobromo-α-d-glucose undergoes invertive oxidative addition to tris(triethylphosphine)palladium(0) to generate a stable, isolable organometallic complex, Pd(PEt3)2(Br)(AcO-β-glucose), which has been fully characterized but is prone to β-acetoxy elimination.
- Munro-Leighton, Colleen,Adduci, Laura L.,Becker, Jennifer J.,Gagne, Michel R.
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scheme or table
p. 2646 - 2649
(2011/06/27)
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- Synthesis of nonnatural nucleoside diphosphate sugars
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Recently, we reported an efficient chemical method for the synthesis of a variety of naturally occurring nucleoside diphosphate (NDP) sugars. This method, which is based on the cycloSal approach, can also be used, in principle, for the preparation of rare or even nonnatural NDP sugars. Herein, the syntheses of sulfoquinovose-, glucose-6-sulfate-, L-galactose-, and 2-fluoroglycopyranoside- containing NDP sugars are presented, as well as the synthesis of NDP sugars with non-natural nucleosides. The reactions described gavestereoisomerically defined NDP sugars in high yields and short reaction times.
- Wolf, Saskia,Berrio, Rosmirt Molina,Meier, Chris
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p. 6304 - 6313
(2011/12/16)
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- Application of silver N-heterocyclic carbene complexes in O-glycosidation reactions
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We report the efficient O-glycosidation of glycosyl bromides with therapeutically relevant acceptors facilitated by silver N-heterocyclic carbene (Ag-NHC) complexes. A set of four Ag-NHC complexes was synthesized and evaluated as promoters for glycosidation reactions. Two new bis-Ag-NHC complexes derived from ionic liquids 1-benzyl-3-methyl-1H-imidazolium chloride and 1-(2-methoxyethyl)-3-methylimidazolium chloride were found to efficiently promote glycosidation, whereas known mono-Ag complexes of 1,3-bis(2,4,6- trimethylphenyl)imidazolium chloride and 1,3-bis(2,6-di-isopropylphenyl) imidazolium chloride failed to facilitate the reaction. The structures of the promoters were established by X-ray crystallography and these complexes were employed in the glycosidation of different glycosyl bromide donors with biologically valuable acceptors, such as estrone, estradiol, and various flavones. The products were obtained in yields considered good to excellent, and all reactions were highly selective for the β isomer regardless of neighboring group effects.
- Talisman, Ian J.,Kumar, Vineet,Deschamps, Jeffrey R.,Frisch, Mark,Malhotra, Sanjay V.
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experimental part
p. 2337 - 2341
(2011/12/04)
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- H2SO4-SiO2: Highly efficient and reusable catalyst for per-O-acetylation of carbohydrates under solvent-free conditions
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Sulfuric acid immobilized on silica gel (H2SO 4-SiO2) was used as an efficient promoter for per-O-acetylation of carbohydrates with acetic anhydride under solvent-free conditions. The substrates include not only monosaccharides and disaccharides, but also glycosides. The catalyst is recyclable and stable at room temperature, and the reaction protocol is simple, is cost-effective, and gives good isolated yield with high purity. The large-scale reactions also proceeded conveniently and in high yields. Taylor & Francis Group, LLC.
- Zhang, Jianbo,Zhang, Bo,Zhou, Jiafen,Li, Juan,Shi, Chunjuan,Huang, Ting,Wang, Zhongfu,Tang, Jie
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experimental part
p. 165 - 177
(2012/01/19)
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- Neighboring-group participation by C-2 ether functions in glycosylations directed by nitrile solvents
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Ether-protecting functions at C-2 hydroxy groups have been found to play participating roles in glycosylations when the reactions are conducted in nitrile solvent mixtures. The participation mechanism is based on intramolecular interaction between the lone electron pair of the oxygen atom of the C-2 ether function and the nitrile molecule when they are positioned in a cis configuration. A 1,2-cis glycosyl oxazolinium intermediate is formed. This participation, in conjunction with the anomeric effect of the glycosyl donor, confers high 1,2-trans selectivities on glycosylations. Further application of this concept has led to efficient preparations of α-(1→5)-arabinan oligomers.
- Chao, Chin-Sheng,Lin, Ching-Yu,Mulani, Shaheen,Hung, Wei-Cheng,Mong, Kwok-Kong Tony
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supporting information; experimental part
p. 12193 - 12202
(2011/12/01)
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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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