Synthesis of postulated molecular probes: stereoselective free-radical-mediated C-glycosylation in tandem with hydrogen transfer.
Reported herein is a strategy employing an addition reaction in tandem with a hydrogen-transfer reaction for the elaboration of C-glycoside-based sialyl Lewis X (sLe(X)) analogues. Significant stereocontrol was noted when alkyl radicals were reacted with a series of alkoxytaconates. Transition states were proposed to explain the obtained selectivity. Further reaction between an anomeric-centered fucosyl-derived radical and a galactosylated hydroxytaconate provided easy access to C,O-diglycosides as mimics of sLe(X). In this case, two 1,3-distant stereocenters were created with high diastereoselectivity using free radical intermediates in a tandem process.
Guindon
Yvan
Y
Bio-organic Chemistry Laboratory, Institut de recherches cliniques de Montréal (IRCM), 110 avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7. guindoy@ircm.qc.ca
Bencheqroun
Mohammed
M
Bouzide
Abderrahim
A
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005609:Free Radicals / Q000737:chemistry; D005690:Galactose / Q000737:chemistry; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D006859:Hydrogen / Q000737:chemistry; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D000080506:Sialyl Lewis X Antigen; D013237:Stereoisomerism; D013644:Tartrates / Q000138:chemical synthesis / Q000737:chemistry; D014961:X-Ray Diffraction
D005609:Free Radicals; D006027:Glycosides; D009844:Oligosaccharides; D000080506:Sialyl Lewis X Antigen; D013644:Tartrates; D006859:Hydrogen; D005690:Galactose