Stereoselective Synthesis of Di- and Trisaccharide Fucoidan Fragments Bearing α-D-Glucuronic Acid Residue∗
摘要:
The first stereoselective synthesis of disaccharide alpha-D-GlcA-(1 -> 2)-alpha-L-Fuc-OPr ( 1), trisaccharide (1 -> 3)-alpha-L-Fuc-[alpha-D-GlcA-(1 -> 2)]-alpha-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 alpha-glycoside bond formation that can be connected with intramolecular remote participation of 3-O-acetyl group favoring alpha-stereoselectivity.
Acid-promoted synthesis of per-O-sulfated fucooligosaccharides related to fucoidan fragments
作者:Vadim B. Krylov、Zinaida M. Kaskova、Dmitry Z. Vinnitskiy、Nadezhda E. Ustyuzhanina、Alexey A. Grachev、Alexander O. Chizhov、Nikolay E. Nifantiev
DOI:10.1016/j.carres.2011.01.005
日期:2011.4
has been performed with the use of previously reported acid-promoted protocol for per-O-sulfation of polyols by SO(3) complexes. During the treatment of (1-->3)-linked oligofucosides under these conditions with the promotion by TfOH, the unusual rearrangement of the reducing pyranose residue into furanose one was observed. To avoid the formation of rearrangement by-products, the use of a series of strong