Complete Assignment of the 360 MHz¹H NMR Spectra of Some Oligomannosides

The 360 MHz 1H NMR spectra of four closely related synthetic oligomannosides have been completely assigned. This was achieved by a combination of spin-tickling difference spectroscopy and spectral simulation. The compounds are: methyl 3-0-(α-D-mannopyranosyl)-α-D-mannopyranoside (II3), methyl 6-0-(α-D-mannopyranosyl) -α-D-mannopyranoside (II6), methyl 3,6-di-0-(α-D-mannopyranosyl) -α-D mannopyranoside (III) and methyl 3-0-(α-D-mannopyranosyl)-6-0-(3-0-α-D-manno-pyranosyl-α-D-mannopyranosyl)-α-D-mannopyranoside (IV). These oligomannosides are analogues 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 of methyl mannotrioside, methyl 3,6-di-0-(α-D-mannopyranosyl)-α-D-mannopyranoside (III); the related disaccharides, methyl 6-0-(α-D-mannopyranosyl)-α-D-mannopyranoside (II6) and methyl 3-0-(α-D-mannopyranosyl)-α-D-mannopyranoside (II3); and a tetrasaccharide, methyl 3-0