Département de chimie moléculaire

{We report herein the synthesis and the X-ray crystal structure of 2-azido-2-deoxy-3,4-O-isopropylidene-$\alpha$-d-galactopyranosyl-N-oxyphthalimide 3 which is the key-precursor of a cancer-related STn antigen analog 5. Compd. 3 crystallizes from a mixt. of dichloromethane/pentane as colorless orthorhombic needles in P21212 space group with the following cell parameters: a = 14.039(2) {\AA}; b = 16.574(3) {\AA}; c = 8.038(1) {\AA}. The hexapyranose ring of 3 adopts a twisted boat according to the Cremer and Pople puckering parameters (Cremer and Pople, J Am Chem Soc 97:1354, 1975) whereas the structure detn. of the corresponding deprotected intermediate 4 (orthorhombic colorless prisms, P2 1 2 1 2 1 space group