Synthesis of Oligosaccharides of Motifs D and E of Arabinogalactan Present in Mycobacterium tuberculosis

Abstract

Syntheses of the ethyl glycosides of 5-O-(beta-D-galactofuranosyl)-beta-D-galactofuranose and 5-O-(alpha-D-arabinofuranosyl)-6-O-(beta-D-galactofuranosyl)-beta-D-galactofuranose present in motifs D and E of Mycobacterium tuberculosis arabinogalactan, respectively, have been presented. The pentenyl-mediated O-glycosylation reaction was utilized to obtain the disaccharide of motif D. The first coupling reaction to prepare the inner disaccharide portion of motif E was accomplished by trichloroacetamidate method while the installation of the terminal sugar by pentenyl glycosylation approach was successful.

A Concise Synthesis of Oligosaccharides Derived From Lipoarabinomannan (LAM) with Glycosyl Donors Having a Nonparticipating Group at C2

“…So, in our hand, peracetylated arabinose 2 was synthesized by methyl glycoside intermediate, acetylation and anomeric acetylation from d ‐arabinose for three steps . Then compound 2 was used to prepare the intermediate 3 by selectively anomeric acetyl deprotection and imidate introduction . Meanwhile the known compound 4 was furnished by anomeric introduction of bromide, ortho‐ester formation, acetyl deprotection, benzylation and anomeric p ‐methylphenyl thioglycoside (STol) introduction for five steps from the same starting material 2 according to the literature .…”

“…Reagents and conditions: Transformations (a–c) have been conducted using reported protocols;, , (d) CH 3 OH, CH 3 ONa, RT, 2 h, 96 %; (e) BF 3 · Et 2 O, 4Å MS, CH 2 Cl 2 , ‐50 °C, 30 min, 86 %.…”

Galactofuranose Antigens, a Target for Diagnosis of Fungal Infections in Humans

“…In Table 3 , the structures of Gal f -containing oligosaccharides, which have been chemically synthesized and are part of fungal glycans, are shown. Most efforts have been directed to the synthesis of oligosaccharides containing Gal f (β1→5)Gal f , the antigenic unit in Aspergillus [ 26 , 77 , 78 , 79 , 80 , 81 , 82 ].…”

Expeditious oligosaccharide synthesis via selective, semi-orthogonal, and orthogonal activation

“…63 The selective activation of trichloroacetimidates over other glycosyl donors can be straightforwardly executed with TMSOTf 64 or BF 3 -OEt 2 . 65 For example, as a part of the synthesis of glycolipid of Mycobacterium smegmatis, TMSOTf-promoted coupling of trichloroacetimidate 49 and thioglycoside acceptor 50 afforded β(1→4) linked trisaccharide 51 in 71% yield (Scheme 13a). 64 …”