title: Significant substituent effect on the anomerization of pyranosides: mechanism of anomerization and synthesis of a 1,2-cis glucosamine oligomer from the 1,2-trans anomer.
abstract: Aminoglycosides containing a 2,3-trans carbamate group easily undergo anomerization from the 1,2-trans glycoside to the 1,2-cis isomer under mild acidic conditions. The N-substituent of the carbamate has a significant effect on the anomerization reaction; in particular, an N-acetyl group facilitated rapid and complete α-anomerization. The differences in reactivity due to the various N-substituents were supported by the results of DFT calculations; the orientation of the acetyl carbonyl group close to the anomeric position was found to contribute significantly to the directing of the anomerization reaction. By exploiting this reaction, oligoaminoglycosides with multiple 1,2-cis glycosidic bonds were generated from 1,2-trans glycosides in a one-step process.
authors.affiliation: RIKEN, Synthetic Cellular Chemistry Laboratory, Hirosawa, Wako, Saitama 351-0198 (Japan), Fax: (+81) 48-462-9430. smanabe@riken.jp.
authors.forename: Shino
authors.initials: S
authors.lastname: Manabe
authors.forename: Hiroko
authors.initials: H
authors.lastname: Satoh
authors.forename: Jürg
authors.initials: J
authors.lastname: Hutter
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Lüthi
authors.forename: Teodoro
authors.initials: T
authors.lastname: Laino
authors.forename: Yukishige
authors.initials: Y
authors.lastname: Ito
mesh_terms: D000617:Aminoglycosides / Q000138:chemical synthesis / Q000737:chemistry*; D003500:Cyclization; D005944:Glucosamine / Q000737:chemistry*; D007536:Isomerism
chemical_list: D000617:Aminoglycosides; D005944:Glucosamine
keywords: carbohydrates; cleavage reactions; density functional calculations; glycosides; isomers