Complete Assignment of the 360 MHz1H NMR Spectra of Some Oligomannosides

Abstract

The 360 MHz 1H NMR spectra of 4 closely related synthetic oligomannosides were completely assigned. This was achieved by a combination of spin-tickling difference spectroscopy and spectral simulation. The compounds are the following: methyl 3-O-(.alpha.-D-mannopyranosyl)-.alpha.-D-mannopyranoside; methyl 6-O-(.alpha.-D-mannopyranosyl)-.alpha.-D-mannopyranoside; methyl 3,6-di-O-(.alpha.-D-mannopyranosyl)-.alpha.-D-mannopyranoside; and methyl 3-O-(.alpha.-D-mannopyranosyl)-6-O-(3-O-.alpha.-D-mannopyranosyl-.alpha.-D-mannopyranosyl)-.alpha.-D-mannopyranoside. These oligomannosides are analogs of the high mannose structures occurring naturally in the N-linked glycopeptides of glycoproteins. A number of long range chemical shift perturbations were observed which are interpreted as being caused by specific interactions arising from the 3-dimensional structure of the oligosaccharides.