- Direct chemical glycosylation with pentenyl- and thioglycoside donors of N-acetylglucosamine
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The use of pentenyl and thiophenyl glycosides of N-acetylglucosamine (GlcNAc) as glycosyl donors for the direct preparation of O-glycosides of GlcNAc promoted by N-iodosuccinimide (NIS) and metal triflates in dichloromethane has been investigated. Both glycosyl acceptors 1-octanol and (-)-menthol resulted in good glycosylation yields for both types of donors with pentenyl glycosides being somewhat superior in terms of yield. Carbohydrate-based acceptors were reacted with a benzylated GlcNAc-pentenyl donor but only provided disaccharides in poor to moderate yields. The results show that a variety of metal triflates are capable of acting as an activator for both NIS and the intermediate oxazoline.
- Krag, Jonas,Christiansen, Mira S.,Petersen, Jette G.,Jensen, Henrik H.
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experimental part
p. 872 - 879
(2010/06/19)
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- H2so4-silica promoted direct formation of β-glycosides of N-Acetyl glycosylamines under microwave conditions
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N-Acetyl glycosamines are important building blocks for the synthesis of biologically active oligosaccharides. This communication describes a simple direct protocol for the synthesis of βglycosides of N-acetyl glycosylamines from easily accessible perO-ac
- Mandai, Santanu,Sharma, Nayan,Mukhopadhyay, Balaram
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experimental part
p. 3111 - 3114
(2010/03/03)
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- N-ACETYLGLUCOSAMINE DERIVATIVES AND USE THEREOF
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The present invention relates to An N-acetylglucosamine derivative represented by the following formula (1), and a hyaluronic acid production promoting agent containing the same and a skin external preparation containing the same: wherein R1 is a hydrogen atom or an alkyl group having 2 to 18 carbon atoms; R2, R3, and R4 are hydrogen atoms or acyl groups having 2 to 18 carbon atoms and may be all the same or different from others; the steric structure at position 1 may be α or β; provided that R1, R2, R3, and R4 must not be all hydrogen atoms. It is intended to provide an easily available hyaluronic acid production promoting agent and a skin external preparation whereby the production of hyaluronic acid can be promoted in the skin and thus the skin can be maintained in a vital and moist state so that it is expected that the human skin can be prevented from age.
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Page/Page column 15
(2010/02/12)
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- Pseudosugars, 40: Synthesis of ether- and imino-linked octyl N-acetyl- 5a'-carba-β-lactosaminides and -isolactosaminides: Acceptor substrates for α-(1→3/4)-fucosyltransferase, and enzymatic synthesis of 5a'- carbatrisaccharides
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Synthesis of ether-linked octyl 5a'-carba-β-lactosaminide 3 and - isolactosaminide 5 was carried out in seven steps, starting from the coupling products of 1,2-anhydro-5a-carba-β-D-mannopyranose derivative 7, and the oxide anions generated from the octyl N-acetyl-β-D-glucosaminide derivatives 13 and 16, respectively, under basic conditions. The 5a-carba-α-D- mannopyranose residues of the coupling products 17 and 26 were transformed into the β-D-gluco configuration through epimerization of the respective 2'- oxo derivatives 19 and 28, and selective reduction, and then into the β-D- galacto configuration by direct nucleophilic substitution of their 4',6'- dimesylates 23 and 31 with an acetate ion. Biological assay has shown that 3 is an acceptor substrate for human-milk α-(1→3/4)-fucosyltransferase and, interestingly, 5 is not. In addition, the imino-linked congeners 4 and 6 have been synthesized by coupling of the 4-amino-4-deoxy- and 3-amino-3-deoxy derivatives 37 and 41 of octyl N-acetyl-β-D-glucosaminide, and the carba- sugar epoxide 8, respectively, and subsequent deprotection. Compound 4 is a substrate while 6 is neither a substrate nor an inhibitor for fucosyltransferase. Small-scale enzymatic synthesis was carried out by treatment of 3 and 4 with GDP-fucose and milk fucosyltransferase, which resulted in conversion into the corresponding trisaccharides 47 and 48, respectively.
- Ogawa, Seiichiro,Matsunaga, Naoki,Li, Hong,Palcic, Monica M.
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p. 631 - 642
(2007/10/03)
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- The synthesis of glycosides of 2-acetamido-2-deoxyglucose catalyzed by mercuric iodide
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The glycosylation of various alcohols with peracetylated α-D-glucosaminyl chloride catalyzed with mercuric iodide was studied along with the dependence of the reaction course on temperature, solvent, and quantity of catalyst. At room temperature, only β-glycosides of peracetylated N-acetylglucosamine were shown to result in dichloroethane or nitromethane with high yields. At 90-95°C, anomerization was observed, which led to the corresponding α-glycosides. The possibility of the synthesis of disaccharides with the β1→6 bond catalyzed by mercuric iodide was demonstrated.
- Zemlyakov,Kur'yanov,Sidorova,Chirva
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p. 551 - 558
(2007/10/03)
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- Alkylating agents from sugars. Cyclophosphamides derived from 2-amino- 2-deoxy-D-allose
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Cyclophosphamides derived from alkyl 2-amino-4,6-O-benzylidene-2-deoxy- β-D-allopyranosides have been synthesized with good yield by treatment of the corresponding 2-amino-2-deoxy-D-allose derivatives with bis(2- chloroethyl)phosphoramide dichloride. The ring-forming reaction took place with very high diastereoselectivity. Subsequent hydrogenolysis gave excellent yields of cyclophosphamides derived from alkyl 2-amino-2-deoxy-β-D- allopyranosides, with hydrophilicity greater than that of the precursors. The starting material was easily available from 2-acetamido-2-deoxy-D-glucose.
- Iglesias-Guerra, Fernando,Romero, Isidora,Alcudia, Felipe,Vega-Perez, Jose M.
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- Iodine: A versatile reagent in carbohydrate chemistry III. Efficient activation of glycosyl halides in combination with DDQ1
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Iodine, either alone or in combination with DDQ, has been found to serve as a very efficient reagent for the conversion of 'disarmed' glycosyl halides into simple 1,2-trans-glycosides. This reagent system represents a practical alternative to traditional
- Kartha, K.P. Ravindranathan,Aloui, Mahmoud,Field, Robert A.
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p. 8807 - 8810
(2007/10/03)
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- Synthesis and surface-active properties of some alkyl 2-amino-2-deoxy-β-D-glucopyranosides
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Several alkyl 2-acetamido-2-deoxy-β-D-glucopyranosides were synthesized using either the oxazoline or the N-allyloxycarbonyl procedure.The latter procedure gave better yields with fatty alcohols and cholesterol.The derivatives thus prepared were partly of fully deprotected and their surface-active properties assessed.Keywords: 2-Amino-2-deoxy-D-glucose; Amphiphiles; Surfactant; 14C-labelled
- Boullanger, Paul,Chevalier, Yves,Croizier, Marie-Christine,Lafont, Dominique,Sancho, Marie-Rose
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