Pyranose

About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.

Liquid crystalline derivatives of galactose and galactitol: dependence of thermotropic mesomorphism on carbohydrate form

Abstract: An almost complete homologous series of the acyclic, open-chain 6- O - n -alkyl-D-galactitols has been prepared. Most homologues in this series exhibit an enantiotropic smectic A* phase. The liquid crystal transition temperatures of these open-chain carbohydrates are compared with those of the corresponding homologues in the cyclic form, i.e., with those of the 6- O - n alkyl-alpha-D-galactopyranoses. In general the carbohydrates in the open-chain form exhibit higher clearing points than those of the analogous cyclic pyranoses. However, the melting point of the galactitols is generally significantly lower than that of the corresponding galactopyranoses. This leads to a much wider temperature range of the smectic A* phase for the carbohydrates in the pyranose form. The lowest clearing point was found for related galactoses in the furanose form. Alternation was found for the clearing point of the 6-O-n alkyl-alpha-D-galactopyranoses and the 6- O - n -alkyl-D-galactitols. Powder X-ray diffraction studies ind...

Derivatives of aldohexoses, intermediates, processes for their manufacture, preparations containing such compounds, and their use

Abstract: Described are derivatives of pyranoses of the formula I, manufacturing processes and intermediates, and their use as medicaments. ##STR1## The pyranose moiety in the compounds of the formula I is derived especially from D-glucose, but alternatively from D-galactose or D-mannose. Characteristic of the compounds of the formula I is the lower alkyl or phenyl-lower alkyl radical R 8 , which carries an oxycarbonyl, mercaptocarbonyl or aminocarbonyl group, which is bonded to an aliphatic, cycloaliphaticaliphatic, cycloaliphatic or aromatic hydrocarbon radical R 0 , each of which is optionally substituted and which may be interrupted by oxycarbonyl, mercaptocarbonyl and/or iminocarbonyl and which, like the remaining radicals of the formula I, is defined in patent claim 1.

Derivation of parameters for conformational calculations on carbohydrate systems, including bacterial cell wall peptidoglycan

Abstract: The use of software designed for the prediction of minimum-energy conformations of peptides and proteins has been extended to include a number of glycoconjugates. For this purpose it was necessary to derive empirical interatomic parameters for sugars consistent with the existing amino-acid parameter set. The principle source is high-grade ab initio quantum-mechanical calculations. Parameters describing the anomeric effect were derived from the ab initio surface of dimethoxymethane. Parameters describing the pyranose ring were optimised against the energy profiles of 2-ethyltetrahydropyran and further refined against the profiles of 2-methoxytetrahydropyran to take account of the anomeric and exo-anomeric effects. Optimisation against the ab initio surface of methoxymethanol was used to study the anomeric hydroxyl. The use of arbitrary rotation potentials to model the anomeric and exo-anomeric effects was avoided by extension of an orbital force field method through specific parametrisation of lone-pair molecular orbitals. Assumptions and limitations inherent in the derivation and use of potentials are discussed.

Glucosylation of Sucrose Laurate with Cyclodextrin Glucanotransferase

Abstract: Sucrose monolauroyl esters were found to serve as substrates for cyclodextrin glucanotransferase (CGTase)-catalyzed transglucosidation reactions, affording new sucrose esters that have an additional 1-3 glucose residues on the pyranose ring of the sucrose moiety in the ester.