Total synthesis of the tumor-associated Lex family of glycosphingolipids

Large-scale chemoenzymatic synthesis of blood group and tumor-associated poly-N-acetyllactosamine antigens

“…4,5 Sialylated and fucosylated derivatives of pLNs have been characterized as specific ligands for different lectins such as selectins and galectins as well as being tumor-associated antigens. [6][7][8][9] Most of the carbohydrate-based antigens are, as a practical matter, not available by isolation. Therefore, the preparation of lactosamine derivatives is crucial for studying their structures and precise interactions with other biomolecules.…”

Strategien zur Erforschung neuer Reaktionen

“…Ein besonders nützliches, nichtexplosives Reagens, das im KilogrammMengen erhältlich ist, ist das von Lal und Mitarbeitern entwickelte Deoxofluor. [117] Aktivierende Reagentien für Glycosylierungen mit Glycosylfluorid wurden in ähnlich großer Zahl entwickelt; Beispiele sind SnCl 2 /AgClO 4 , [102] SnCl 2 /TrClO 4 , [107] SnCl 2 / AgOTf, [128] SiF 4 , [129] Me 3 SiOTf, [129] BF 3 ·OEt 2 , [130] [133,134] Bu 2 Sn(ClO 4 ) 2 , [135] Me 2 GaCl, [136] Tf 2 O, [137] LiClO 4 , [138] Yb(OTf) 3 , [139] La(ClO 4 ) 3 ·n H 2 O, [140] La(ClO 4 ) 3 ·n H 2 OSn(OTf) 2 , [141] Yb-Amberlyst 15, [142] sulfatiertes Zirconiumdioxid, [143] TrB(C 6 F 5 ) 4 , [144,145] TfOH, [145][146][147] HClO 4 , [147] HB(C 6 F 5 ) 4 , [147] Carbokationen (B(C 6 F 5 ) 4 À -und TfO À -Salze), [148] SnCl 2 /AgB(C 6 F 5 ) 4 , [149] SnCl 4 /AgB(C 6 F 5 ) 4 , [150] Ce(ClO 4 ) 3 . [151] Unser ursprünglicher Aktivator, SnCl 2 / AgClO 4 , wurde erfolgreich in der Totalsynthese von Glycosphingolipiden (Schema 37) [152,153] und von Cyclodextrin (Schema 38) eingesetzt.…”

Recent trends in the synthesis of O-glycosides of 2-amino-2-deoxysugars

“…362,408 Nucleophilic displacement of an anomeric halide with the salt of the thiol is also a viable route. [409][410][411] Glycosidation of thioglycosides can be achieved with the use of a variety of acceptors. 412 For example, NIS/TfOH-promoted reaction of glycosyl donor 138 with glycosyl acceptor 144 afforded oligosaccharide 145 in 91% yield (Scheme 26).…”