- Total Synthesis of the Potent and Broad-Spectrum Antibiotics Amycolamicin and Kibdelomycin
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The complex and intriguing structures of the antibiotics amycolamicin and kibdelomycin are herein confirmed through total synthesis. Careful titration of the synthetic products reveals that kibdelomycin is the salt form of amycolamicin. This synthesis emp
- Chen, Chenglong,Chen, Jie,Li, Chao,Yang, Shaoqiang
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supporting information
p. 21258 - 21263
(2021/12/17)
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- A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
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The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn2+-promoted redox isomerization step, which proceeds via sugar radical intermediates accessed by neutral hydrogen atom abstraction under visible light-mediated photoredox conditions. The resulting deoxyketopyranosides feature chemically distinguishable functional groups and are readily transformed into diverse carbohydrate structures. To showcase the versatility of this method, we report expedient syntheses of the rare sugars l-ristosamine, l-olivose, l-mycarose, and l-digitoxose from commercial l-rhamnose. The findings presented here validate the potential for radical intermediates to facilitate the selective transformation of carbohydrates and showcase the step and efficiency advantages attendant to synthetic strategies that minimize a reliance upon protecting groups.
- Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
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p. 13798 - 13805
(2021/09/07)
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- An efficient and scalable synthesis of 2,4-di-N-acetyl-l-altrose (l-2,4-Alt-diNAc)
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Bacterial nonulosonic acids such as pseudaminic acids and others constitute a family of 9-carbon monosaccharides that contain a common 3-deoxy-2-ketoacid fragment but differ in their stereochemistries at 5 stereogenic centers between C-4 to C-8. Their unique structures make them attractive targets for use as antigens in vaccinations to combat drug-resistant bacterial infections and their challenging stereochemistries have attracted considerable attention from chemists. In this work we report the development of an improved synthesis for 2,4-di-N-acetyl-l-altrose (l-2,4-Alt-diNAc), which is a key hexose required for the chemical and chemoenzymatic synthesis of pseudaminic acids. Usingl-fucose as a starting material, our synthesis overcomes several pitfalls in previously reported syntheses.
- Niedzwiecka, Anna,Sequeira, Carita,Zhang, Ping,Ling, Chang-Chun
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p. 11583 - 11594
(2021/03/31)
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- Boronic Acids as Phase-Transfer Reagents for Fischer Glycosidations in Low-Polarity Solvents
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Protocols employing phenylboronic acid as a phase-transfer reagent for Fischer glycosidations in low-polarity organic solvents are described. In addition to providing rate acceleration, the formation of a substrate-derived boronic ester alters the course of the reaction by selective promotion of a furanoside- or pyranoside-selective pathway. Computational modeling of the relative energies of the glycoside-derived boronic esters provides results that are qualitatively consistent with the observed distributions of furanoside versus pyranoside products. The boronic esters that are obtained as direct products of these reactions serve as protected intermediates for the synthesis of functionalized glycosides. Complexation of particular diol groups by the boronic acid also enables selective transformations of mixtures of carbohydrates.
- Manhas, Sanjay,Taylor, Mark S.
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p. 11406 - 11417
(2017/11/10)
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- Direct glycosylation of bioactive small molecules with glycosyl iodide and strained olefin as acid scavenger
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A new strategy for diversity-oriented direct glycosylation of bioactive small molecules was developed. This reaction features (-)-β-pinene as acid scavenger and work with glycosyl iodides under mild conditions. With the aid of RP-HPLC and chiral SFC separation techniques, the new direct glycosylation proved effective at gram scale on bioactive small molecules including AZD6244, podophyllotoxin, paclitaxel, and docetaxel. Interesting glycoside derivatives were efficiently created with good yields and 1,2-cis selectivity.
- Gu, Xiangying,Chen, Lin,Wang, Xin,Liu, Xiao,You, Qidong,Xi, Wenwei,Gao, Li,Chen, Guohua,Chen, Yue-Lei,Xiong, Bing,Shen, Jingkang
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p. 1100 - 1110
(2014/03/21)
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- Application of the Wharton rearrangement for the de novo synthesis of pyranosides with ido, manno, and colito stereochemistry
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A de novo asymmetric synthesis of α-ido-pyranosides, as well as several deoxy and amino variants, has been achieved. The procedure involves a palladium(0)-catalyzed glycosylation in combination with a Wharton rearrangement/epoxide-opening reaction sequence to access sugars with ido, manno, and colito stereochemistry as well as several azido analogues. A de novo asymmetric synthesis of α-ido-pyranosides, as well as several deoxy and amino variants, has been achieved. The procedure involves a palladium(0)- catalyzed glycosylation in combination with a Wharton rearrangement/epoxide- opening reaction sequence to access sugars with ido, manno, and colito stereochemistry as well as several azido analogues. Copyright
- Cuccarese, Michael F.,Wang, Hua-Yu Leo,O'Doherty, George A.
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p. 3067 - 3075
(2013/06/27)
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- Regioselective removal of the anomeric O-benzyl from differentially protected carbohydrates
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A mild, regioselective deprotection of the anomeric O-benzyl from multi-functionally protected carbohydrates via catalytic transfer hydrogenation is described. The protocol is tolerant of O-benzyl and O-benzylidene protections at non-anomeric positions, g
- Jalsa, Nigel Kevin
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p. 6587 - 6590
(2012/02/03)
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- Efficient glycosylation of unprotected sugars using sulfamic acid: A mild eco-friendly catalyst
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Sulfamic acid, a mild and environmentally benign catalyst has been successfully used in the Fischer glycosylation of unprotected sugars for the preparation alkyl glycosides. A diverse range of aliphatic alcohols have been used to prepare a series of alkyl glycosides in good to excellent yield.
- Guchhait, Goutam,Misra, Anup Kumar
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experimental part
p. 52 - 57
(2012/01/15)
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- De novo synthesis of deoxy sugar via a Wharton rearrangement
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A highly divergent synthesis of α-fuco-, α-6-deoxy-allo-, α-6-deoxy-altro-pyranosides has been achieved. This route utilizes a Wharton rearrangement as part of a new post-glycosylation transformation strategy.
- Wang, Hua-Yu Leo,O'Doherty, George A.
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p. 10251 - 10253
(2011/10/19)
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- De novo asymmetric synthesis of anthrax tetrasaccharide and related tetrasaccharide
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(Chemical Equation Presented) A de novo asymmetric approach to the natural product anthrax tetrasaccharide 1 and an analogue 2 with an anomeric hexyl azide group has been developed from acetylfuran. The construction of the tetrasaccharide was achieved by
- Guo, Haibing,O'Doherty, George A.
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p. 5211 - 5220
(2008/12/21)
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- De novo asymmetric synthesis of the anthrax tetrasaccharide by a palladium-catalyzed glycosylation reaction
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(Chemical Equation Presented) Choose your poison: In the de novo asymmetric synthesis of the anthrax tetrasaccharide 1 (25 steps from acetylfuran), the absolute configurations of three L sugars and one D sugar were set by the Noyori reduction of acetylfuran with the S,S and the R,R reagent, respectively. The configuration of the remaining carbohydrate unit was set by highly diastereoselective palladium-catalyzed glycosylation and post-glycosylation transformations.
- Guo, Haibing,O'Doherty, George A.
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p. 5206 - 5208
(2008/03/14)
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- Oligomerization of a rhamnanic trisaccharide repeating unit of O-chain polysaccharides from phytopathogenic bacteria
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An efficient synthesis of a protected trisaccharide building block α-L-Rha(1→3)-α-L-Rha(1→2)-α-L-Rha related to the structure of many lipopolysaccharide O-chains from phytopathogenic bacteria has been developed. The protecting group pattern consisting of benzoyl, benzyl and chloroacetyl groups facilitated the use of the trisaccharide building block in the synthesis of two higher oligomers, an oligorhamnosyl hexasaccharide and a nonasaccharide.
- Bedini, Emiliano,Parrilli, Michelangelo,Unverzagt, Carlo
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p. 8879 - 8882
(2007/10/03)
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- Synthesis of β-D-ribofuranosyl-(1→3)-α-L-rhamnopyranose by in situ activating glycosylation using 1-OH sugar derivative and Me3SiBr-CoBr2-Bu4NBr-molecular sieves 4A system
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Β-D-Ribofuranosyl-(1→3)-α-L-rhamnopyranosyl-(1→3)- L-rhamnopyranose, the trisaccharide repeating unit of the C. freundii O28, 1c O-specific polysaccharide, was synthesized using in situ activating glycosylation of the 1-OH sugar derivatives and a reagent mixture of trimethylsilyl bromide, cobalt(II) bromide, tetrabutylammonium bromide, and molecular sieves 4A. Regioselective tritylation was useful for synthesizing the 3-OH derivatives of methyl, allyl, and benzyl α-L-rhamnosides.
- Hirooka,Mori,Sasaki,Koto,Shinoda,Morinaga
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p. 1679 - 1694
(2007/10/03)
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- On the regioselectivity of the protease subtilisin towards the acylation of enantiomeric pairs of benzyl and naphthyl glycopyranosides. Part 2
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Subtilisin-catalyzed esterification of several enatiomeric benzyl and naphthyl glycopyranosides has been investigated. The D-sugar derivatives were all good substrates and subtilisin regioselectivity was similar with all the compounds tested, the 3-OH being acylated predominantly. On the other hand, most of the L-glycopyranosides were transformed during longer reaction times with a lower regioselectivity, the 2-OH being preferentially but not exclusively acylated.
- Danieli, Bruno,Peri, Francesco,Roda, Gabriella,Carrea, Giacomo,Riva, Sergio
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p. 2045 - 2060
(2007/10/03)
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- Synthesis and absolute configuration of lepidimoide, a high potent allelopathic substance from mucilage of germinated cress seeds
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Lepidimoide (1), 1,2-cis-linked dissacharide, was synthesized from D-glucose and α-L-rhamnose for determination of the absolute configuration.
- Kosemura,Yamamura,Kakuta,Mizutani,Hasegawa
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p. 2653 - 2656
(2007/10/02)
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- Alternative syntheses of L-(-)-oleandrose from L-rhamnose. Preparation of glycals
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L-Rhamnal (2) is prepared from L-rhamnose (3) by use of an improved generalized Fischer-Zach reaction. L-Rhamnal (2) is then converted to L-(-)-oleandrose (1) by stannylene mediated selective methylation and effective hydration. Benzyl α-L-oleandrose (12) is prepared by selective methylation and deoxygenation of L-rhamnose (3).
- Bredenkamp,Holzapfel,Toerien
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p. 2459 - 2477
(2007/10/02)
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- The Photochemistry of Ketones derived from Carbohydrates. Part 9. Formation of O- and C-Ribofuranoside Derivatives by Photodecarbonylation of O-and C-Glycosides of lyxo-Hexopyranos-4-ulose Derivatives
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The syntheses of 6-deoxy-2,3-O-isopropylidene-α-L-lyxo-hexopyranosyl-4-ulose-ethane (7) and -benzene (8), and the assignment of their anomeric configurations by 1H and 13C n.m.r. spectroscopy, are described.The preparations of a number of O-glycosid-4-ulo
- Collins, Peter M.,Travis, Anthony S.
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p. 779 - 786
(2007/10/02)
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