| Glucal and fucal were converted into glycosyl fluorides by the sequence: epoxidation, fluorohydrin formation using tetrabutylammonium fluoride or triethylamine trihydrogen fluoride, then protection of the C-2 hydroxyl function. These species have been shown to be useful glycosyl donors for oligosaccharide syntheses. By buffering the glycosylation with the non-nucleophilic base, 2,6 di-tert-butylpyridine, glucal was able to be used as the glycosyl acceptor to form 1,2-cis disaccharides.; The tetrasaccaride sialyl Lewis{dollar}sp{lcub}rm X{rcub}{dollar} (sLe{dollar}sp{lcub}rm X{rcub}){dollar}, found at the non-reducing termini of glycoproteins and glycolipids on the surface of leukocytes mediates adhesion of leukocytes to the vascular endothelium in areas of inflammation by binding the endothelial surface glycoprotein E-selectin. This tetrasaccharide and higher congeners were synthesized in a highly concise fashion by selective fucosylation of a mono-protected glucal derivative using the above methodology. Galactosylation followed by sialylation provided the key intermediate tetrasaccharide glycal. This compound was rapidly parlayed into the target structures through stannyl alkoxide mediated sulfonamidoglycosylation by other members of the research group.; Gangliosides are cell surface glycolipids containing at least one sialic acid residue. They have been implicated as controllers of many cellular functions. G{dollar}sb{lcub}rm M4{rcub}{dollar} is the simplest of the gangliosides but contains a structural element common to many others. G{dollar}sb{lcub}rm M4{rcub}{dollar} was synthesized by selective sialylation of a mono-protected galactal derivative followed by ceramide introduction. Surprisingly, by permuting the timing of the sialylation and ceramide introduction, a previously unknown G{dollar}sb{lcub}rm M4{rcub}{dollar} regioisomer was prepared. |
