An access to various sulfation patterns in dermatan sulfate: chemical syntheses of sulfoforms of trisaccharide methyl glycosides
作者:Nadine Barroca、Jean-Claude Jacquinet
DOI:10.1016/s0008-6215(02)00060-5
日期:2002.4
The syntheses are reported for the first time of alpha-L-IdopA(2)SO(3)-(1-->3)-beta-D-GalpNAc4SO(3)-(1-->4)-alpha-L-IdopA2SO(3)-(1-->OMe), its disulfated analogue alpha-L-IdopA2SO(3)-(1-->3)-beta-D-GalpNAc4SO(3)-(1-->4)-alpha-L-IdopA2SO(3)-(1-->OMe), and of beta-D-GalpNAc4SO(3)-(1-->4)-alpha-L-IdopA2SO(3)-(1-->3)-beta-D-GalpNAc4SO(3)-(1-->OMe), which represent structural fragments of dermatan sulfate, unavailable directly by chemical or enzymatic degradation of the glycosaminoglycan polymer. These molecules were readily obtained from a pair of key disaccharide intermediates, in which the relative difference of stability of the D-GalNAc 4-hydroxy protecting groups (acetate or pivalate) toward saponification conditions allowed access to various sulfoforms from a common precursor. For the preparation of these blocks, the 4-O-pivaloyl-D-galacto moiety was readily obtained through a one-pot stereospecific intramolecular nucleophilic displacement on an easily available 3-O-pivaloyl-D-gluco precursor,and the L-IdoA moiety through selective radical oxidation at C-6 of a L-ido 4,6-diol derivative with oxoammonium salts. (C) 2002 Elsevier Science Ltd. All rights reserved.