Synthesis of l-glycero- and d-glycero-d-manno-Heptose Building Blocks for Stereoselective Assembly of the Lipopolysaccharide Core Trisaccharide of Vibrio parahemolyticus O2

Abstract

Synthesis of bacterial cell surface l-glycero-d-manno-heptose (l,d-Hep)- and d-glycero-d-manno-heptose (d,d-Hep)-containing higher carbon sugars is a challenging task. Here, we report a convenient and efficient approach for the synthesis of the l,d-Hep and d,d-Hep building blocks. Using l-lyxose and d-ribose as starting materials, this approach features diastereoselective Mukaiyama-type aldol reactions as the key steps. On the basis of the synthetic l,d-Hep and d,d-Hep building blocks, we achieved the first stereoselective synthesis of the unique α-l,d-Hep-(1→3)-α-d,d-Hep-(1→5)-α-Kdo core trisaccharide of the lipopolysaccharide of Vibrio parahemolyticus O2.

Mukaiyama aldol reaction: an effective asymmetric approach to access chiral natural products and their derivatives/analogues

“…However, an efficient strategy for their synthesis was still required. For this purpose, Wang et al 134 in 2020 reported the total synthesis of LPS core trisaccharide 1 of V. parahemolyticus O2 by utilizing the Mukaiyama aldol reaction as one of the main steps. In order to achieve the synthesis of the l , d -Hep subunit, they reacted l -lyxose 274 via several steps to obtain chiral aldehyde 275 , which was further subjected to react with silyl enol ether 276 by the Mukaiyama aldol reaction in the presence of MgBr 2 ·OEt 2 , DCM and toluene.…”

Bacterial polysaccharides—A big source for prebiotics and therapeutics

“…In gram-negative bacteria, some rare monosaccharides such as L-glycero-D-manno-heptose and D-glycero-D-manno-heptose along with Kdo are usually found in the inner core region of the lipopolysaccharides, and occasionally they are also present as a part of the outer core and O-antigens. As integral part of the LPS, these monosaccharides have significant role in host-bacterium interactions, therefore, they can be used for the inhibition studies of bacterial cell wall polysaccharide synthesis and stimulation of the host immune system ( 21 ).…”

Stereoselective Synthesis of β-d-Manno-heptopyranoside via Cs2CO3-Mediated Anomeric O-Alkylation: Synthesis of a Tetrasaccharide Repeat Unit of Bacillus thermoaerophilus Surface-Layer Glycoprotein

“…Furthermore, l - glycero - d - manno -heptose was also prepared by de novo synthesis based on Mukaiyama-type aldol reaction . Recently, Yang and co-workers reported an efficient approach for the synthesis of d - glycero - d - manno -heptose and l - glycero - d - manno -heptose via Mukaiyama-type aldol reactions using d -ribose and l -lyxose as starting materials, respectively …”