Glycal scavenging in the synthesis of disaccharides using mannosyl iodide donors.
[reaction: see text] High mannose glycans composed of alpha (1-->2) and alpha (1-->6) branched sugars are important components of the HIV-associated envelope glycoprotein, gp120. These substructures can be efficiently prepared in solution from glycosyl iodide precursors requiring only a slight excess of the iodide donor, which offers advantages over solid-phase methods that require more than 5 equiv of donor. During the reaction, excess iodide is converted to a glycal that is not easily separated from the desired disaccharide. To overcome this difficulty, a phase-trafficking methodology that relies upon nucleophilic interception of the 1,2 anhydrosugar resulting from oxidation of the glycal has been developed.
Lam
Son N
SN
University of California, Davis, Department of Chemistry, One Shields Avenue, Davis, California 95616, USA.
Gervay-Hague
Jacquelyn
J
D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000138:chemical synthesis*; D006027:Glycosides / Q000737:chemistry*; D007454:Iodides / Q000737:chemistry*; D008358:Mannose / Q000737:chemistry*; D008969:Molecular Sequence Data
D004187:Disaccharides; D006027:Glycosides; D007454:Iodides; D008358:Mannose