C2-amidoglycosylation. Scope and mechanism of nitrogen transfer.
A one-pot C2-amidoglycosylation reaction for the synthesis of 2-N-acyl-2-deoxy-beta-pyranosides from glycals is described. Glycal donors activated by the reagent combination of thianthrene-5-oxide (11) and Tf2O, followed by treatment with an amide nucleophile and a glycosyl acceptor, lead to the formation of various C2-amidoglycoconjugates. Both the C2-nitrogen transfer and the glycosidic bond formation proceed stereoselectively, allowing for the introduction of both natural and nonnatural amide functionalities at C2 with concomitant anomeric bond formation in a one-pot procedure. Tracking of the reaction by low-temperature NMR spectroscopy employing 15N- and 18O-isotope labels suggests a mechanism involving the formation of the C2-sulfonium glycosyl imidate 39 as well as oxazoline 37 as key intermediates in this novel oxidative glycosylation process.
Liu
Jing
J
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Gin
David Y
DY
D001372:Aza Compounds / Q000138:chemical synthesis*; D006027:Glycosides / Q000138:chemical synthesis*; D006031:Glycosylation; D009584:Nitrogen / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular
D001372:Aza Compounds; D006027:Glycosides; D009584:Nitrogen