Chemoenzymatic Synthesis of Neoglycopeptides: Application to an α-Gal-Terminated Neoglycopeptide
摘要:
A novel methodology; for the enzymatic preparation from suitably derivatized oligosaccharides of N-linked neoglycopeptides using the microbial glutaminyl-peptide gamma -glutamyl transferase, transglutaminase (TGase), is described, N-Allyl glycosides of various oligosaccharides were photochemically coupled with cysteamine to yield amino-terminated thioether spacers, which were accepted by transglutaminase to transamidate the side-chain gamma -carboxamide group in the dipeptide Z-Gln-Gly.
[reaction: see text]. A new one-pot method is described for the removal of O- and N-allyl protecting groups under oxidative conditions at near neutral pH. The allyl group undergoes hydroxylation and subsequent periodate scission of the vicinaldiol, followed by repetition of this reaction sequence on the enolic form of the aldehyde intermediate.
An Efficient Synthesis of <i>N</i>-Allylglycosylamides from Unprotected Carbohydrates
作者:Wayne Spevak、Falguni Dasgupta、Christopher J. Hobbs、Jon O. Nagy
DOI:10.1021/jo9522522
日期:1996.1.1
Synthetic, multivalent, carbohydrate assemblies are important tools in studying the avidity of many naturally occuring lectins for their ligands. This report details a simple, high-yielding three-step procedure to convert unprotected carbohydrates into N-allylglycosides. This method compliments the reductive amination procedure but allows the reducing-end pyranose ring to remain intact. No carbohydrate protecting groups are needed, and the resulting N-allylglycosylamide can be easily linked to other molecules. Two examples of analogs of silyl Lewis(x) and sulfo Lewis(x) have been derivatized by this process.