213906-18-4Relevant academic research and scientific papers
Regio- and stereoselective synthesis of β-D-gluco-, α-L-ido-, and α- L-altropyranosiduronic acids from Δa4-uronates
Bazin, Helene G.,Wolff, Michael W.,Linhardt, Robert J.
, p. 144 - 152 (2007/10/03)
The stereoselective synthesis of β-D-glucopyranosiduronic, α-L- idopyranosiduronic, and α-L-altropyranosiduronic acids has been performed from different Δ4-uronate monosaccharides. Bromination of the C-4,5 double bond provided the trans-diaxial bromohydrin derivatives, which were converted to the corresponding epoxides in high yields. Direct reduction of the epoxides using boranetetrahydrofuran complex led to the corresponding glucuronic acids in low to good yields. Glucuronic acids were also obtained in satisfactory yields through a two-steps procedure involving bromination of the epoxide with titanium(IV) bromide followed by reduction using tributyltin hydride. Lewis acid-catalyzed rearrangement of these epoxides led to the corresponding α-L C-4 ketopyranosides adopting the 1C4 chair conformation. Hydride reduction afforded the α-L-idopyranosiduronic or the α-L- altropyranosiduronic acids, the stereoselectivity of the reduction being controlled by the appropriate substitution pattern.
Conformational study of synthetic Δ4-uronate monosaccharides and glycosaminoglycan-derived disaccharides
Bazin, Helene G.,Capila, Ishan,Linhardt, Robert J.
, p. 135 - 144 (2007/10/03)
Sixteen Δ4-uronate monosaccharides were chemically synthesized. Their carboxy group was protected as a methyl or benzyl ester, the anomeric hydroxyl group as a benzyl glycoside and the 2 and 3 hydroxyl groups were protected with different substitution patterns as both ester and ether derivatives. Disaccharides containing Δ4-uronates were prepared from heparin using heparin lyases. Their carboxy group was unprotected or protected as a benzyl ester and the two hydroxyls in the uronate moiety were free, as O-sulfo derivatives or acylated. The conformation of these unsaturated uronate monosaccharide and disaccharide residues was studied using 1H NMR by examining interproton vic inal coupling constants. The Δ4-uronate residue adopted either the 2H1 or the 1H2 conformations. The equilibrium between these two conformers was shown to be controlled by substitution pattern.
