n-Pentenyl Glycosides as Mediators in the Asymmetric Synthesis of Monosubstituted Chiral Nonracemic Tetrahydrofurans and γ-Lactones

Article abstract of DOI:10.1021/jo00297a005

n-Pentenyl glycosides can be oxidatively hydrolyzed by treatment with N-bromosuccinimide, previous work having been focused on the usefulness of the resulting glycosyl moiety.In this paper, attention is focused on asymmetric induction in the 2-(bromomethyl)furan that is liberated.The enantiomeric excess depends strongly on the orientations at the anomeric centers and at C2, as well as on the protecting group on the C2 oxygen. α-Anomers display higher asymmetric induction, and rationalization of this observation is based on the assumption that the molecule reacts from the favored ground-state orientation, wherein the exo anomeric effect is displayed.The usefulness of this route to optically active furans has been probed by a synthesis of an insect pheromone from the Bledius species.