Synthesis 2024; 56(07): 1139-1146
DOI: 10.1055/s-0040-1720095
paper
Emerging Trends in Glycoscience

Expeditious Synthesis of the Hexasaccharide Repeating Unit of the Capsular Polysaccharide of Streptococcus pneumoniae Type 7A

Swapan Kumar Jana
,
Samim Sahaji
,
Pradip Shit
,
Anup Kumar Misra
This work was supported by SERB, New Delhi (Project No. CRG/2019/000352 dated 23.01.2020) (AKM).


Abstract

The hexasaccharide repeating unit corresponding to the capsular polysaccharide of Streptococcus pneumoniae type 7A has been synthesized in good yield using [3+2+1] block synthetic strategy. The synthetic strategy involved a number of challenging stereoselective glycosylation steps, which include β-selective glycosylation of l-rhamnosyl thioglycoside donor, α-selective glycosylations of 2-azido-2-deoxy-d-glucopyranosyl thioglycoside donor and d-galactopyranosyl donor together with the formation of β-glycoside of d-galactosamine moiety and α-glycoside of l-rhamnosyl moiety. Suitably functionalized thioglycosides have been used as glycosyl donors and a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf­) has been used as glycosylation promoter.

Supporting Information



Publication History

Received: 03 July 2023

Accepted after revision: 04 October 2023

Article published online:
08 November 2023

© 2023. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany