SYNTHESIS AND POLYCONDENSATION OF GALACTO-CONFIGURATED MONOMERS VIA THE TRITYL-CYANOETHYLIDENE-PROCEDURE

-cyano)ethylidene]-3-O-trityl-alpha-D-fucopyranose (13) and methyl eth ylidene]-3-O-trityl-alpha-D-galactopyranuronate (14) were synthesised. Trityl-cyanoethylidene condensation of the monomer 14 gave protected beta-D-GalpA-(1-->3)-D-GalpA-oligosaccharide derivatives with high ste reoselectivity and a degree of polymerisation (d.p.) of eight. In the case of the D-fucose monomer 13, the yield of oligomers is surprisingl y low and the d.p. does not exceed seven. This result is in contrast t o the d.p. 20 - 60 obtained with other 6-deoxy-sugars, as previously d escribed by Kochetkov and coworkers.