Syntheses and interfacial behaviour of neoglycolipid analogues of glycosylceramides

Four glycosyl ceramides analogues having D-galactose or 2-acetamido-2-deoxy -D-glucose moieties linked to enantiomeric lipids have been synthesised to study their interfacial behaviour at the air \ water interface. The lipid c hains were prepared in two steps by opening 1,2-epoxyhexadecane using Jacob sen kinetic hydrolytic resolution (KHR) followed by an azidosilylation reac tion of the diol so obtained. Glycosylation reactions were realised either with 2,3,4,6-tetra-O-benzoyl-alpha -D-galactopyranosyl trichloroacetimidate or 1,3,4,6-tetra-O-acetyl-2-allyloxycarbonylamino-2-deoxy-beta -D-glucopyr anose as donors and (2R)- or (2S)-2-azidohexadecanol derivatives as accepto rs. Transformation of the azido glycosides into N-acylated products was don e by a modified Staudinger reaction in the presence of fatty acyl chlorides . The four neoglycolipids are able to form a condensed monolayer at the air \ water interface; their pi -A isotherm diagrams are similar to that descr ibed for the natural glycosyl ceramides. The detailed analysis of the isoth erms, taking into account the chirality of the lipid chains, allowed to det ermine the contribution of the different parts of the molecule under the mo nolayer packing. (C) 2001 Elsevier Science Ltd. All rights reserved.