OLIGOSACCHARIDES RELATED TO TUMOR-ASSOCIATED ANTIGENS .1. SYNTHESIS OF THE PROPYL GLYCOSIDE OF THE TRISACCHARIDE ALPHA-L-FUCP-(1 -] 2)-BETA-D-GALP-(1 -] 3)-BETA-D-GALP NAC, COMPONENT OF A TUMOR-ANTIGEN RECOGNIZED BY THE ANTIBODY MBR1

The synthesis of the trisaccharide alpha-L-Fucp-(1-->2)-beta-D-Galp-(1-->3)-beta-D-GalpNAc-1-OPr (2) is described. The N-acetylgalactosamine 6 was obtained from 4 by an intramolecular displacement of a (trifluoromethyl)sulfonyloxy by a pivaloyloxy group with its concomitant migration from position 3 to position 4 (Scheme 1). The galactosyl donor 9 was obtained from 7 via 8 by regioselective opening of the orthoester function with AcOH/pyridine followed by treatment with CCl3CN and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (Scheme 2). Glycosylation of 6 with 9 in the presence of BF3.OEt2 gave the disaccharide 10. Selective deprotection of 10 at O -C(2') followed by glycosylation with 12 and by standard deprotection afforded the title trisaccharide 2 (Scheme 3). Preliminary biological testing showed that 2 is able to inhibit the binding of the monoclonal antibody MBr1 to the target tumor celles MCF7 in a dose-dependent manner.