Synthesis and Evaluation of 5‐Thio‐L‐Fucose‐Containing Oligosaccharide

Abstract

5‐Thio‐L‐fucose‐containing trisaccharide H‐type II was synthesized. The 3′,4′‐O‐isopropylidene‐2‐azido‐2‐deoxylactoside derivative, which was prepared from lactose by azidonitration of lactal, was used as a starting material. By regio‐ and stereoselective 5‐thio‐L‐fucosylation of the 6,6′‐dibenzoate 5 with 5‐thiofucosyl trichloroacetimidate 6 and subsequent deprotection gave the 5‐thio‐L‐fucose‐containing H‐type II 1. Conformational analysis of the 5‐thio‐L‐fucose‐containing H‐type II and the native H‐type II was carried out through NOESY experiments. The observed NOE values between N‐acetylglucosamine and galactose, and galactose and fucose were same for these two trisaccharides. However, NOE values between fucose and N‐acetylglucosamine were significantly different. Binding of the 5‐thio‐L‐fucose‐containing H‐type II to lectins and antibodies were in some case stronger and in some case weaker than those of the native trisaccharide.