Glycolipids from sponges. 20. J-Coupling analysis for stereochemical assignments in furanosides: structure elucidation of vesparioside B, a glycosphingolipid from the marine sponge Spheciospongia vesparia.
Reinvestigation of the glycosphingolipid composition of the marine sponge Spheciospongia vesparia revealed the presence of vesparioside B ( 2a), a new furanose-rich hexaglycosylated glycosphingolipid that is the most complex glycosphingolipid isolated from a marine sponge to date. The structure of the new compound was elucidated using extensive 2D NMR studies and chemical degradation. Particularly useful for structure elucidation of vesparioside B was a quantum mechanical computational study, showing that in furanosides a vicinal coupling constant <2.0 Hz (for H-1/H-2 or H-3/H-4) or <3.5 Hz (for H-2/H-3) is a proof of the trans orientation of the relevant protons. This general rule, combined with ROE data, allowed us to elucidate the relative stereochemistry (including anomeric configuration) of the three furanose five-membered rings.
Costantino
Valeria
V
Dipartimento di Chimica delle Sostanze Naturali, Università di Napoli "Federico II", via D. Montesano 49, 80131 Napoli, Italy.
Fattorusso
Ernesto
E
Imperatore
Concetta
C
Mangoni
Alfonso
A
D000818:Animals; D002236:Carbohydrate Conformation; D005663:Furans / Q000737:chemistry*; D006028:Glycosphingolipids / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D009844:Oligosaccharides / Q000737:chemistry; D011161:Porifera; D011714:Pyrans / Q000737:chemistry; D013237:Stereoisomerism
D005663:Furans; D006028:Glycosphingolipids; D009844:Oligosaccharides; D011714:Pyrans