Threshold of Thioglycoside Reactivity Difference Is Critical for Efficient Synthesis of Type I Oligosaccharides by Chemoselective Glycosylation.
J Org Chem
; 86(1): 892-916, 2021 01 01.
Article
em En
| MEDLINE
| ID: mdl-33320008
ABSTRACT
Synthesis of type I LacNAc (Galß1 â 3GlcNAc) oligosaccharides usually suffers from low yields. We herein report the efficient synthesis of type I LacNAc oligosaccharides by chemoselective glycosylation. With 16 relative reactivity values (RRVs) measured thiotoluenyl-linked disaccharide donors and acceptors, chemoselective glycosylations were investigated to obtain optimal conditions. In these reactions, the RRV difference between the donors and acceptors had to be more than 6311 to obtain type I LacNAc tetrasaccharides in 72-86% yields, with minimal occurrence of aglycon transfer. The threshold of RRV difference was further applied to plan the synthesis of longer glycans. Because it is challenging to measure the RRVs of tetrasaccharides, anomeric proton chemical shifts were utilized to predict the corresponding RRVs, which consequently explained the outcome of glycosylations for the synthesis of type I LacNAc hexasaccharides. The result supported the idea that elongation of glycan chains has to proceed from the reducing to the nonreducing end for a better yield.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Taiwan