Synthetic studies on glycosphingolipids from protostomia phyla: Synthesis of neogala-series glycolipid analogues containing a mannose residue from the earthworm Pheretima hilgendorfi

Two kinds of glycosphingolipid analogues from the earthworm Pheretima hilgendorfi were synthesized as follows: the trisaccharide 2- (tetradecyl)hexadecyl α-D-mannopyranosyl-(1→4)-β-D-galactopyranosyl- (1→6)-β-D-galactopyranoside (13) and the tetrasaccharide 2-(tetradecyl) hexadecyl α-D-galactopyranosyl-(1→6)-[α-D-mannopyranosyl-(1→4)]-β-D- galactopyranosyl-(1→6)-β-D-galactopyranoside (20) were synthesized by stepwise condensation of suitably protected monosaccharide units. A 2- (trimethylsilyl)ethyl 2,3,4-tri-O-benzoyl-β-D-galactopyranoside derivative (5) was used as the glycosyl acceptor and thiophenyl derivatives of D- galactose and D-mannose were used as donors respectively.