title: Effect of electron-withdrawing protecting groups at remote positions of donors on glycosylation stereochemistry.
abstract: Here we review the equatorial β-directing effects of electron-withdrawing protecting groups at remote positions of mannopyranosyl donors, mannuronate donors, rhamnopyranosyl donors, and 2,6-dideoxyglucopyranosyl donors. We discuss the equatorial α-directing effect of an electron-withdrawing group at the N-5 position of sialyl donors. The proposed mechanism and origin of some of the equatorial β-directing effects are described. We also review the effects of potentially participating, electron-withdrawing protecting groups at remote positions of glycopyranosyl and glycofuranosyl donors on the glycosylation stereochemistries. Further, we present substantial evidence in favor of the remote participation by the electron-withdrawing protecting groups and also include reports that are opposed to remote participation.
authors.affiliation: Center for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul, 120-749, Korea. kwan@yonsei.ac.kr
authors.forename: Kwan Soo
authors.initials: KS
authors.lastname: Kim
authors.forename: Dae-Hwan
authors.initials: DH
authors.lastname: Suk
mesh_terms: D004583:Electrons; D006027:Glycosides / Q000737:chemistry*; D006031:Glycosylation; D008358:Mannose / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D006027:Glycosides; D008358:Mannose