- Tandem reduction-reductive alkylation of azido sugars
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Catalytic hydrogenation of azido sugars has been conducted in the presence of different aldehydes to bring about a tandem reduction-reductive alkylation sequence. The reaction sequence proceeds in generally high yields, and tolerates some benzyl and benzylidene protecting groups that are sensitive to hydrogenolysis.
- Chen, Liqiang,Wiemer, David F.
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- Synthesis of 1,2,3-triazolyl analog of Neisseria meningitidis A capsular polysaccharide
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Towards constructing a stable, non-hydrolyzable linkage for Neisseria meningitidis type A (MenA) polysaccharide, the phosphate bridge of its (1→6)-linked 2-acetamido-2-deoxy-α-D-mannopyranosyl phosphate repeating unit was replaced by a triazolyl analog using Cu(I) catalyzed click reaction. The synthesis involved anomeric azidation of N-acetyl-D-mannosamine derivative from its acetate precursor using stoichiometric amount of FeCl3 and one-pot synthesis of precursors for di- and tri- triazolyl saccharides with an azidoethyl spacer at the reducing end for bioconjugation.
- Vangala, Madhuri,Hotha, Srinivas
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p. 393 - 413
(2019/01/04)
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- Modular hydroxyamide and thioamide pyranoside-based ligand library from the sugar pool: New class of ligands for asymmetric transfer hydrogenation of ketones
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A large library of pyranoside-based hydroxyamide and thioamide ligands has been synthesized for asymmetric transfer hydrogenation in an attempt to expand the scope of the substrates to cover a broader range of challenging heteroaromatic and aryl/fluoroalkyl ketones. These ligands have the advantage that they are prepared from commercial D-glucose, D-glucosamine and α-amino acids, inexpensive natural chiral feedstocks. By carefully selecting the ligand components (substituents/configurations at the amide/thioamide moiety, the position of amide/thioamide group and the configuration at C-2), we found that pyranoside-based thioamide ligands provided excellent enantioselectivities (in the best cases, ees of >99% were achieved) in a broad range of ketones, including the less studied heteroaromatics and challenging aryl/fluoroalkyls. Note that both enantiomers of the reduction products can be obtained with excellent enantioselectivities by simply changing the absolute configuration of the thioamide substituent.
- Coll, Mercè,Pàmies, Oscar,Diéguez, Montserrat
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p. 2293 - 2302
(2014/07/21)
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- Carbohydrate-derived aminoalcohol ligands for asymmetric Reformatsky reactions
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Members of a family of functionally and stereochemically diverse d-glucosamine-derived tertiary aminoalcohol ligands have been used to promote the asymmetric Reformatsky reaction. The β-hydroxyester product tert-butyl 3-phenyl-3-hydroxy-propanoate was obt
- Emmerson, Daniel P.G.,Hems, William P.,Davis, Benjamin G.
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p. 213 - 221
(2007/10/03)
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- Precise structure activity relationships in asymmetric catalysis using carbohydrate scaffolds to allow ready fine tuning: dialkylzinc-aldehyde additions.
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The ready construction of 24 stereochemically and functionally diverse carbohydrate ligand structures from a core D-glucosamine scaffold has allowed the evaluation of broad ranging structure activity relationships in ligand accelerated zincate additions t
- Emmerson, Daniel P G,Villard, Renaud,Mugnaini, Claudia,Batsanov, Andrei,Howard, Judith A K,Hems, William P,Tooze, Robert P,Davis, Benjamin G
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p. 3826 - 3838
(2007/10/03)
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- N-BENZOYLCARBAMATE CYCLIZATIONS
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The anion of an alcohol derived N-benzoylcarbamate may be used to deliver nitrogen intramolecularly to electrophilic centers.This allows the stereocontrolled synthesis of a variety of amino-alcohol and amino-diol derivatives.
- Knapp, Spencer,Kukkola, Paivi J.,Sharma, Shashi,Pietranico, Sherrie
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p. 5399 - 5402
(2007/10/02)
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- Di- and Polyamino Sugars, XXXI. - Substitution Reactions of 2-Amino-2-deoxy-β-D-glucopyranosides at Position 3
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Neighboring-group participations obstruct nucleophilic substitutions of N-protected 2-amino-2-deoxy-3-O-mesyl-β-D-glucopyranosides with azide ions.From the N-dinitrophenyl derivative 8 besides the allopyranoside 10 the isomeric products 9 and 11 are forme
- Meyer zu Reckendorf, Wolfgang,Lenzen, Heinz-Juergen
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p. 477 - 484
(2007/10/02)
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