4692-12-0Relevant articles and documents
Photoinitiated glycosylation at 350 nm
Cumpstey, Ian,Crich, David
experimental part, p. 469 - 485 (2012/06/15)
A method for photochemical activation of glycosyl donors is presented. Selenoglycosides were activated by single-electron transfer using a photooxidant, N-methylquinolinium hexafluorophosphate, as photosensitizer and a toluene cosolvent as cosensitizer under irradiation at 350 nm. In this way we were able to synthesize glycosides including (1→6)-linked disaccharides. Benzyl ethers and benzoate esters were compatible with these conditions, allowing potentially synthetically useful transformations. The major by-products were due to hydrolysis; the reactions required the presence of oxygen and were run in air.
An efficient method for the preparation of glycosides with a free C-2 hydroxyl group from thioglycosides
Yu, Hai,Ensley, Harry E.
, p. 9363 - 9366 (2007/10/03)
A new and efficient method to produce glycosides with a free C-2 hydroxyl group through 1,2-acyl group migration which occurs during the hydrolysis of 4,6-benzylidene protected thioglycosides has been developed. The acyl transfer products allow for further elaboration.
Carbohydrate Homologation by the Use of 2-(Trimethylsilyl)thiazole. Preparative Scale Synthesis of Rare Sugars: L-Gulose, L-Idose, and the Disaccharide Subunit of Bleomycin A2
Dondoni, Alessandro,Marra, Alberto,Massi, Alessandro
, p. 6261 - 6267 (2007/10/03)
The well established one-carbon homologation method of protected monosaccharides employing 2-(trimethylsilyl)thiazole (2-TST) as a formyl anion equivalent has been used for high yield and multigram scale synthesis of the title rare hexoses from L-xylose. Thus, L-gulose has been obtained by stereoselective anti-addition of 2-TST to aldehydo-L-xylose diacetonide followed by thiazole to formyl conversion of the resulting alcohol. The inversion of configuration at C-1 of this alcohol by an oxidation - reduction sequence prior to the aldehyde releasing from thiazole led to L-idose. The same alcohol was readily elaborated into 1,3,4,6-tetra-O-acetyl-L-gulopyranose whose highly stereoselective glycosidation coupling with 3-O-carbamoyl-2,4,6-tri-O-acetyl-α-D-mannosyl diethyl phosphate afforded the same peracetylated disaccharide subunit employed by Boger and Honda in the total synthesis of the antibiotic bleomycin A2.
Glycosylation of triterpene alcohols and acids of the lupane and A-secolupane series
Klinotova, Eva,Krecek, Vaclav,Klinot, Jiri,Endova, Magdalena,Eisenreichova, Jana,Budesinsky, Milos,Sticha, Martin
, p. 1776 - 1798 (2007/10/03)
A series of 3- and 28-glucosides and glucosyl esters of betulinic acid (1a), 28-hydroxy-3,4-secolupa-4(23),20(29)-dien-3-oic acid (22a), dimethyl ester of 28-hydroxy-2,3-secolup-20(29)-en-2,3-dioic acid (43a), their 20(29)-dihydro derivatives (1b, 22b, 43b) and several other triterpenes of the lupane (12a, 12b) and 3,4-secolupane series (18a, 18b, 32a) has been prepared by reaction of tetra-O-acetyl-α-D-glucopyranosyl bromide in acetonitrile in the presence of mercury(II) cyanide and subsequent deacetylation of the obtained tetra-O-acetyl-β-D-glucopyranosyl derivatives. In several cases attempted glucosylation in the presence of silver silicate afforded predominantly the corresponding 1,2-orthoacetates of α-D-glucopyranose.
An electrochemical synthesis of methyl α-isomaltoside
Hamann, Carl Heinz,Polligkeit, Herbert,Wolf, Peter,Smiatacz, Zygfryd
, p. 1 - 8 (2007/10/02)
A novel approach has been developed for the synthesis of methyl α-isomaltoside (10), comprising, as the first step, electrochemical conversion of the hydroxyl groups of methyl α-D-glucopyranoside into the corresponding anions.The anions subsequently react with tetra-O-acetyl-α-D-glucopyranosyl bromide to give methyl 2',3',4',6'-tetra-O-acetyl-α-isomaltoside (8) as the main product.O-deacetylation of which affords 10.The glycosidation proceeds under complete stereochemical control.Keywords: Isomaltoside, methyl α-; Disaccharides; Electrochemical synthesis; Structure
A COMPARISON OF BIS(TRIBUTYLTIN) OXIDE, POTASSIUM CYANIDE, AND POTASSIUM HYDROXIDE AS REAGENTS FOR THE REGIOSELECTIVE 1-O-DEACETYLATION OF FULLY ACETYLATED SUGARS
Watanabe, Kazuko,Itoh, Kiyotaka,Araki, Younosuke,Ishido, Yoshiharu
, p. 165 - 176 (2007/10/02)
Treatments of fully acetylated sugars with bis(tributyltin) oxide in toluene at reflux, and with potassium cyanide or potassium hydroxide, or both, in mixtures of tetrahydrofuran and 2-propanol were found to be effective for regioselective 1-O-deacetylation of fully acetylated sugars.
Syntheses and 1H- and 13C-Nuclear Magnetic Resonance Spectra of All Positional Isomers of Tetra-O-acetyl-D-glucopyranoses, and Their Monobenzyl and Monotrityl Derivatives
Utamura, Toshiko,Kuromatsu, Keiko,Suwa, Kiyoko,Koizumi, Kyoko,Shingu, Tetsuro
, p. 2341 - 2353 (2007/10/02)
All the isomers of the tetra-O-acetyl-D-glucopyranoses, and their monobenzyl and monotrityl derivatives were synthesized and systematic 1H- and 13C-nuclear magnetic resonance (1H- and 13C-NMR) studies were carried out.Complete assignments of the 1H- and 13C-NMR signals were achieved by 1H- and 13C-decoupling techniques and by the use of a shift reagent and changes of solvents.Moreover, when necessary, 1H- and 13C-shift-correlated 2D NMR spectroscopy at higher frequency (Bruker AM 400) was applied.The shifts on deacetylation, benzylation, and tritylation were estimated on the basis of the 1H- and 13C-chemical shifts of these compounds, and the effects of deacetylation and benzyl- or trityl-substitution are discussed.Keywords - tetra-O-acetyl-D-glucopyranose; monobenzyl tetra-O-acetyl-D-glucopyranose; monotrityl tetra-O-acetyl-D-glucopyranose; 1H-NMR; 13C-NMR; deacetylation shift; benzylation shift; tritylation shift
