title: Approximate H(5) Ring Conformation of 2,3-O-Carbonate Protected α- and β-L-Rhamnopyranosides as Confirmed by X-Ray Crystallography.
abstract: 2,3-O-Carbonate protected rhamnopyranosides with both the α- and β-anomeric configuration are shown crystallographically to have ring conformations that differ significantly from the chair and which approach the (o)H(5) half-chair. This distortion, which is greatest in the α-anomer, provides a basis for the α-selectivity of 2,3-O carbonate protected manno- and rhamnopyranosyl donors as well as the conformationally related 2,3-O-alkylidene derivatives, in homogeneous solution phase glycosylation reactions.
authors.forename: David
authors.initials: D
authors.lastname: Crich
authors.forename: A U
authors.initials: AU
authors.lastname: Vinod
authors.forename: John
authors.initials: J
authors.lastname: Picione
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Wink