Study of the Glycosidation Properties of 1‐Thiomannosazidopyranosides and 1‐Thiomannosaziduronic Acid Esters

Abstract

A study of the glycosylation properties of 1‐thiomannosazides with a variety of electron‐withdrawing substituents in combination with the Ph2SO/Tf2O and NIS/TMSOTf reagent systems is presented. Further, assembly of the fully protected trisaccharide 26, which corresponds to the repeating unit of the enterobacterial common antigen, using both an orthogonal and a chemoselective coupling strategy and based on the outcome of our glycosylation studies, is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Uronic Acids in Oligosaccharide Synthesis

“…Global deprotection afforded alginate trisaccharide 128 . In the same way, 1‐thio‐functionalized mannosaziduronic acid showed promise as a donor and acceptor glycoside in carbohydrate chemistry 95…”

Synthetic Enterobacterial Common Antigen (ECA) for the Development of a Universal Immunotherapy for Drug‐Resistant Enterobacteriaceae

“…Furthermore, all its glycosidic linkages have 1,2- cis -configurations including a β- N -acetyl- d -mannosaminuronic acid (β- d -Man p NAcA), which are difficult to install in a stereoselective manner. [15] Also, β- d -Man p NAcA has poor glycosyl donor and acceptor properties and readily forms a lactam. The latter problem was compounded by the fact that an anomeric aminopentyl linker needed to be installed limiting the possibilities of amino-group manipulations.…”

“…It is well know that d -mannosaminuronic esters have a propensity to form 2,6-lactams, and previously Birch reduction was employed for the deprotection of such oligosaccharides. [15a] Such a strategy is, however, not feasible for ECA-derived compounds due to the presence of base sensitive acetyl esters. The need to simultaneously reduce six azido groups further complicated the deprotection.…”

Synthesis of a New Type ofd-Mannosamine Glycosyl Donor and Acceptor and their Use for the Preparation of Oligosaccharides Consisting ofd-Mannosamine Units Linked by α(1→4)-Glycosidic Bonds

“…This approach incorporates a masked amino functionality and stereoselection of the glycosidation reaction can be effectively controlled by steric and electronic substituent effects. [11][12][13] The 4,6-O-benzylideneprotected donors generally afford b-glycosides, and thus offers an improvement on existing methods. 11,12 While initially explained by torsional strain, 14 the significance of electronic effects of C(4) and C(6) substituents on the stereochemical outcome of glycosylation was recently reported.…”

“…11,12 While initially explained by torsional strain, 14 the significance of electronic effects of C(4) and C(6) substituents on the stereochemical outcome of glycosylation was recently reported. 13 In 2006, we reported 15 the synthesis of ethyl 2-azido-2deoxy-1-thio-b-D-mannopyranosides as potential building blocks for the preparation of oligosaccharides requiring (1→4)-linked 2-azido-2-deoxy-D-mannopyranose units. We demonstrated that the electronic interaction between the axially oriented azido group at C(2) and the equatorial sulfur at atom C(1) on the activated mannopyranoside led to significant deactivation of the alkylsulfanyl moiety as the desired leaving group.…”