title: A general, iterative, and modular approach toward carbohydrate libraries based on ruthenium-catalyzed oxidative cyclizations.
abstract: Carbohydrates are an omnipresent class of highly oxygenated natural products. Due to their wide spectra of biological activities, they have been in the center of synthetic organic chemistry for more than 130 years. During the past 50 years non-natural carbohydrates attracted the interest of various chemists in the fields of organic, biological, and medical chemistry. Especially desoxygenated sugars proved to be an important class of compounds. Up to date, most non-natural analogues are synthesized starting from natural, enantiomerically pure carbohydrates in multistep synthesis. In this report, we present a synthetic strategy that allows the selective modular synthesis of natural and non-natural carbohydrates within five synthetic steps starting from readily available starting materials. Due to a sequential introduction of O- or N-functionalities, a regioselective protection of each new functional group is possible. The key step in the carbohydrate synthesis is a RuO4-catalyzed oxidative cyclization via a pH-dependent dehydrogenation-dihydroxylation-cyclization or an oxidative fragmentation-cyclization, leading to highly substituted new carbohydrates, in which each functional group is orthogonally protected and accessible for further synthetic operations.
authors.affiliation: Institüt für Organische Chemie, Fakultät Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Meike
authors.initials: M
authors.lastname: Niggemann
authors.forename: Andreas
authors.initials: A
authors.lastname: Jelonek
authors.forename: Nicole
authors.initials: N
authors.lastname: Biber
authors.forename: Margarita
authors.initials: M
authors.lastname: Wuchrer
authors.forename: Bernd
authors.initials: B
authors.lastname: Plietker
mesh_terms: D000215:Acylation; D002241:Carbohydrates / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D006863:Hydrogen-Ion Concentration; D006865:Hydrogenation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry*; D054852:Small Molecule Libraries; D013237:Stereoisomerism
chemical_list: D002241:Carbohydrates; D054852:Small Molecule Libraries; D012428:Ruthenium