Oligosaccharides Related to Tumor‐Associated Antigens. Part I. Synthesis of the propyl glycoside of the trisaccharide α‐<scp>L</scp>‐Fuc<i>p</i>‐(1 → 2)‐β‐<scp>D</scp>‐Gal<i>p</i>‐(1 → 3)‐β‐<scp>D</scp>‐Gal<i>p</i>NAc, component of a tumor antigen recognized by the antibody MBr1

Abstract

Abstract The synthesis of the trisaccharide α‐ L ‐Fuc p ‐(1 → 2)‐β‐ D ‐Gal p ‐(1 → 3)‐β‐ D ‐Gal p NAc‐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 CCl 3 CN and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) ( Scheme 2 ). Glycosylation of 6 with 9 in the presence of BF 3 · OEt 2 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 MBrl to the target tumor cells MCF7 in a dose‐dependent manner.