1607433-73-7Relevant academic research and scientific papers
Expedient Route to Access Rare Deoxy Amino l-Sugar Building Blocks for the Assembly of Bacterial Glycoconjugates
Sanapala, Someswara Rao,Kulkarni, Suvarn S.
, p. 4938 - 4947 (2016)
Bacterial glycoproteins and oligosaccharides contain several rare deoxy amino l-sugars which are virtually absent in the human cells. This structural difference between the bacterial and host cell surface glycans can be exploited for the development of carbohydrate based vaccines and target specific drugs. However, the unusual deoxy amino l-sugars present in the bacterial glycoconjugates are not available from natural sources. Thus, procurement of orthogonally protected rare l-sugar building blocks through efficient chemical synthesis is a crucial step toward the synthesis of structurally well-defined and homogeneous complex glycans. Herein, we report a general and expedient methodology to access a variety of unusual deoxy amino l-sugars starting from readily available l-rhamnose and l-fucose via highly regioselective, one-pot double serial and double parallel displacements of the corresponding 2,4-bistriflates using azide and nitrite anions as nucleophiles. Alternatively, regioselective monotriflation at O2, O3, and O4 of l-rhamnose/l-fucose allowed selective inversions at respective positions leading to diverse rare sugars. The orthogonally protected deoxy amino l-sugar building blocks could be stereoselectively assembled to obtain biologically relevant bacterial O-glycans, as exemplified by the first total synthesis of the amino linker-attached, conjugation-ready tetrasaccharide of O-PS of Yersinia enterocolitica O:50 strain 3229 and the trisaccharide of Pseudomonas chlororaphis subsp. aureofaciens strain M71.
Solvent-Free Glycosylation from per-O-Acylated Donors Catalyzed by Methanesulfonic Acid
Bedini, Emiliano,Iadonisi, Alfonso,Silipo, Alba,Traboni, Serena,Vessella, Giulia
, p. 5669 - 5676 (2021/11/11)
The huge importance of carbohydrates and their derivatives in biomedical and industrial applications call for the development of streamlined and sustainable procedures for their synthetic elaboration. Here reported a novel glycosylation method based on direct activation of readily available per-O-acylated (acetylated or benzoylated) donors, promoted under air by methanesulfonic acid as a cheap and green catalyst in the absence of any solvent. Besides the beneficial avoidance of toxic and polluting organic solvents, these conditions were found critical for activating such poorly reactive donors with a very small catalyst loading (only 5 mol %), instead of stoichiometric Lewis acid promoters typically employed. Desired glycosides were quickly obtained, in most cases with high 1,2-trans stereoselectivity. Other main advantages over reported glycosylations with similar donors are the limited stoichiometric excess of the acceptor (or the donor), the easy applicability and low cost of the procedure and the wide target scope, also covering the synthesis of disaccharides and other non-trivial glycosides with applicable potential.
Stereoselective synthesis of a sulfated tetrasaccharide corresponding to a rare sequence in the galactofucan isolated from Sargassum polycystum
Zhou, Jun,Yang, Liping,Hu, Wenhao
, p. 4718 - 4726 (2014/06/09)
The first chemical synthesis of a highly sulfated tetrasaccharide 1, as the rare sequence in the galactofucan isolated from the brown alga Sargassum polycystum, was achieved in a convergent and stereoselective manner. The key features of the synthetic str
Concise synthesis of the repeating units of the cell wall lipopolysaccharide of azospirillum brasilense SR80
Mandal, Pintu Kumar,Dhara, Debashis,Misra, Anup Kumar
, p. 1947 - 1953 (2014/07/22)
Syntheses of trisaccharide and tetrasaccharide repeating units of the cell wall lipopolysaccharide of Azospirillum brasilense SR80 as their 4-methoxyphenyl (PMP) glycosides have been achieved following a sequential glycosylation strategy in good yield. All intermediate steps are high-yielding and the glycosylation steps are highly stereoselective. Georg Thieme Verlag Stuttgart New York.
