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.