PHYSICAL STUDIES ON OLIGOSACCHARIDES RELATED TO SUCROSE .I. NMR STUDIES ON PERACETATES OF SUCROSE 1-KESTOSE AND NYSTOSE

The n.m.r. spectra of sucrose octaacetate (1), 1-kestose hendecaacetane (2), and nystose tetradecaacetate (3) were measured in benzene-d6, chloroform-d, and acetone-d6, at 100 and 220 MHz. Signals of H-1, 2, 3, and 4 of the α-d-glucopyranosyl residue, and of H-3 and H-4 of the β-d-fructofuranosyl residue(s), could be observed individually for each of the compounds. The data confirm that all d-fructose residues in 1-kestose and nystose are in the furanoid ring-form. Observation of a two-proton, AB system near τ 6.3 (chloroform-d) in the spectrumof 2 provides diagnostic evidence for the (2↔1) linkage between the two d-fructofuranosyl residues in 1-kestose [β-d-Fruf-(2→1)-β-d-Fruf-(2↔1)-α-d-Gp]; other conceivable linkages are excluded. A second such AB system, observed in the spectrum of 3, establishes that nystose is built up from 1-kestose by (2→1) attachment of an additional d-fructofuranosyl group. Other points of attachment are excluded, and the structure β-d-Fruf-(2→1)-β-d-Fruf-(2→1)-β-d-Fruf-(2↔ 1)-α-d-Gp previously suggested for nystose, is confirmed. The n.m.r. signals for H-2, 3, and 4 of the α-d-glucopyranosyl residue in 1, 2, and 3, and also in methyl α-d-glucopyranoside tetraacetate (4), showed close correlation. © 1969.