Stereoselective Synthesis of Di- and Trisaccharide Fucoidan Fragments Bearing α-D-Glucuronic Acid Residue∗

∗Synthesis, NMR, and Conformational Studies of Fucoidan Fragments. Part 10. For Part 9 see [1].

Abstract

The first stereoselective synthesis of disaccharide α -d-GlcA-(1 → 2)-α-l-Fuc-OPr (1), trisaccharide (1 → 3)-α-l-Fuc-[α -d-GlcA-(1 → 2)]-α -l-Fuc-OPr (3), and their selectively O-sulfated derivatives 2 and 4 bearing sulfo-groups at O(4) of the fucose units has been performed. Compounds 1– 4 represent the fragments of the chain of the fucoidan from Cladosiphon okamuranus brown seaweed. Glucuronylation by a series of selectively O-acetylated glucuronyl bromides was studied to obtain the target products. It has been found that 3-O-acetylated donor 6 is the most efficient agent for α -glycoside bond formation that can be connected with intramolecular remote participation of 3-O-acetyl group favoring α-stereoselectivity.

Keywords:

• Fucoidan
• Cladosiphon okamuranus brown seaweed
• fucosylation
• glucuronylation
• O-sulfation

ACKNOWLEDGMENTS

This work was supported by the Russian Foundation for Basic Research (grant 06-03-33080). We also thank Dr. Yu. E. Tsvetkov for helpful discussions and critical reading of the manuscript.

Notes

∗Synthesis, NMR, and Conformational Studies of Fucoidan Fragments. Part 10. For Part 9 see [1].