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Oligosaccharides; 2D 1H NMR phase‐sensitive correlated spectroscopy; Chemical shifts; Coupling constants; Connectivities
Abstract:
Pure absorption phase‐sensitive shift‐correlated 1H NMR spectra were shown to furnish complete information on chemical shifts, their connectivities (including one‐ and two‐step remote connectivities) and coupling constants for oligosaccharides of considerable complexity. Therefore, a strategy using these spectra as a first step in ab initio structure elucidation of carbohydrates may require less effort and spectrometer time than alternative strategies exploiting J‐resolved, double quantum and relayed coherence transfer spectra. All these methods and also triple quantum filtered spectra were applied in order to compare their merits and to identify the constituent sugar residues of three peracetylated glycosphingolipids, viz. Galα(1–3)Galβ(1–4)GlcNAcβ(1–3)Galβ(1–4)Glcβ(1–1)Cer(Cer=ceramide),Galα(1–3)Galβ(1–4)GlcNAcβ(1–3)[Galα(1–3)Galβ(1–4)GlcNAcβ(1–6)]Galβ(1–4)GlcNAcβ(1–3)Galβ(1–4)Glcβ(1–1)Cer and GalNAcβ(1–3)Galα(1–4)Galβ(1–4)Glcβ(1–1)Cer(globoside).
