226382-85-0Relevant articles and documents
Exploration of conformational flexibility and hydrogen bonding of xylosides in different solvents, as a model system for enzyme active site interactions
R?nnols, Jerk,Manner, Sophie,Siegbahn, Anna,Ellervik, Ulf,Widmalm, G?ran
, p. 5465 - 5472 (2013/09/02)
The predominantly populated conformation of carbohydrates in solution does not necessarily represent the biologically active species; rather, any conformer accessible without too large an energy penalty may be present in a biological pathway. Thus, the conformational preferences of a naphthyl xyloside, which initiates in vivo synthesis of antiproliferative glycosaminoglycans, have been studied by using NMR spectroscopy in a variety of solvents. Equilibria comprising the conformations 4C1, 2S O and 1C4 were found, with a strong dependence on the hydrogen bonding ability of the solvent. Studies of fluorinated analogues revealed a direct hydrogen bond from the hydroxyl group at C2 to the fluorine atom at C4 by a 1hJF4,HO2 coupling. Hydrogen bond directionality was further established via comparisons of fluorinated levoglucosan molecules. The Royal Society of Chemistry.
Studies on the reaction of D-glucal and its derivatives with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]Octane salts
Ortner,Albert,Weber,Dax
, p. 297 - 316 (2007/10/03)
The reaction of D-glucal and its derivatives with the electrophilic N-F-fluorination reagents F-TEDA tetrafluoroborate and triflate was studied by means of 19F NMR spectroscopy. In all cases mixtures of 2-deoxy-2-fluoro-D-gluco- and -D-mannopyranose derivatives were formed, the ratio of which was dependent on the nature of the O-protecting groups. Concerning the products arising from the direct addition of reagents across the double bond, the D-gluco-configured compounds (13-20) generally showed higher hydrolysis rates than their D-manno-counterparts (21-28). Product separation was only achieved when single anomers (e.g., 2,4-dinitrophenyl glycosides 29e/37e and disaccharidic fluorides 35d/43d) or per-O-acetates (e.g. 29f/37f) were formed.
