Partially benzylated oxazoline derivatives of 2-acetamido-2-deoxy-D-glucopyranose as "standardized intermediates" for oligosaccharide synthesis. preparation of disaccharides having the sequences β-D-GlcpNAc(1→x)-D-Gal and β-D-GlcpNAc(1→4)-D-GlcNAc

Three benzyl tri-O-benzyl-l-thio-β-D-galactopyranosides (5, 6, and 7) were prepared from the corresponding O-acyltri-O-benzyl-D-galactopyranosyl bromides (1a-c) via the benzylxanthates 2a-c and the fully protected benzyl thiogalactosides 3a-c. The α anomer (4) of 5 resulted from the reaction of bromide 1a with α-toluenethiol. Conditions were found for the successful coupling of O-acetyl-di-O-benzyl derivatives (8 and 13) of 2-methyl-(1,2-dideoxy-α-D-glucopyrano)-[2,1-d]-2-oxazoline to the thiogalactosides 5-7, and to a partially protected glycoside (16) or 2-acetamido-2-deoxy-D-glucose. The products were fully substituted disaccharides of 2-acetamido-2-deoxy-β-D-glucose linked 1→3 (9a), 1→6 (11a), 1→4 (14a), and 1→4 (17a), respectively. Cleavage of the single, temporary protecting group (O-acetyl) from these compounds gave partially deblocked disaccharides capable of chain extension from position 3′ (9b and 11b) or 4′ (14b and 17b). © 1981.