Glycoside seleno

Nicolaou KC, Mitchell HJ, Flyaktakidou KC, Suzuki H, Rodriguez RM, 1,2-Seleno migrations in carbohydrate chemistry Solution and solid-phase synthesis of 2-deoxy glycosides, orthoesters, and allyl orthoesters, Angew. Chem. Int. Ed., 39 1089-1093, 2000. 

The selective activation of glycoside trichloroacetimidates over phenyl selenoglycosides was also demonstrated by glycosidation of phenyl seleno-glycoside acceptors 168 and 169 with glycosyl trichloroacetimidate 172. In the presence of catalytic amounts of triethylsilyl trifluoromethanesulfonate at -78°C, the disaccharide derivatives 170 and 171 were obtained in respectively 84 and 90% yields. 

Beau and coworkers prepared 1,2-frans-seleno acetates by addition of PhSeCl to electron-rich glycals 71 in the presence of AgOAc (Scheme 34 route A) [214]. Subsequently, these acetates 86 selectively gave 0-glycosides 87 a in the presence of TMSOTf as a promoter. Ogawa [215] and Frank [216] and their coworkers... 

Yamago S, Yamada T, Ito H, Hara O, Mino Y, Yoshida J. Combinatorial synthesis of an oligosaccharide library by using beta-bromoglycoside-mediated iterative glycosylation of seleno-glycosides rapid expansion of molecular diversity with simple building blocks. Chem. Eur. J. 2005 11 6159-6174. 

Nicolaou, K C, Fylaktakidou, K C, Mitchell, H J, van Delft, F L, Rodriguez, R M, Conley, S R, Jin, Z, Total synthesis of eveminomicin 13,384-1 — part 4 explorations of methodology stereocontrolled synthesis of l,T-disaccharides, 1,2-seleno migrations in carbohydrates, and solution- and solid-phase synthesis of 2-deoxy glycosides and orthoesters, Chem. Eur. J., 6, 3166-3185, 2000. 

Replacement of the exocyclic anomeric oxygen atom in a glycoside by sulfur or selenium produces the corresponding 1-thio- or a 1-seleno-glycoside. Certain 1-thioglycosides occur in Nature and others are important as glycosidase inhibitors.98-100... 

A major use for 1-thio- and 1-seleno-glycosides is in the synthesis of O-linked glycosides and oligosaccharides.101... 

Glycosyl fluorides, which have many applications in chemical and biomedical studies, are obtainable by treatment of both 1-seleno- and 1-telluro-glycosides with diethylaminosulfur trifluoride (DAST).176... 

It was also possible to reactivate the anomeric centre through a differentiation of activity at the anomeric centre during the synthesis of di- and oligosaccharides. A corresponding example is shown in the reaction sequence of Scheme 5. Pinto [19,20] observed that seleno-glycosides are more reactive and could there-... 

Simple vinyl glycosides may be obtained via seleno Inter-nedlates (Scheme 5) and, with the carbene derived from ethyl llazoacetate, can be converted into compounds such as (20). ... 

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