Regioselective Galactofuranosylation for the Synthesis of Disaccharide Patterns Found in Pathogenic Microorganisms

• DOI: 10.1021/acs.joc.7b00565
• Publication Date: 2017-06-20T11:58:25Z
• Authors: Laurent Legentil; Yari Cabezas; Olivier Tasseau; Charles Tellier; Franck Daligault; Vincent Ferrières
• Keywords: Disaccharide

Koenigs-Knorr glycosylation of acceptors with more than one free hydroxyl group by 2,3,5,6-tetrabenzoyl galactofuranosyl bromide was performed using diphenylborinic acid 2-aminoethyl ester (DPBA) as inducer regioselectivity. High regioselectivity for the on equatorial acceptor obtained thanks to transient formation a borinate adduct corresponding 1,2-cis diol. Nevertheless orthoester byproducts hampered efficiency method. Interestingly electron-withdrawing groups O-6 or C-1 displaced reaction in favor desired containing disaccharide. The best yield furanosylation p-nitrophenyl 6-O-acetyl mannopyranoside. Precursors other disaccharides, found glycocalix some pathogens, were synthesized according same protocol yields ranging from 45 86%. This is good alternative synthesis biologically relevant glycoconjugates.