Synthesis of a set of di- and tri-sulfated galabioses

Among cell-adhesion molecules, L-selectin recognizes sulfated sLe(x) with r elatively low affinity. Here, we aimed at artificial mimics by synthesizing a set of di- and tri-sulfated galabioses, which may surpass the affinity o f sulfated sLe(x). As a strategy to obtain 3',6',6-tri-O-sulfogalabioses, r egioselective reductive cleavage of 4,6- and 4',6'-di-O-benzylidenegalabios es was employed. Two suitably protected galactose precursors were conjugate d to yield alpha and beta anomers (48 and 18%, respectively) by using a pen tenyl galactoside donor and iodinium di-sym-collidine perchlorate as the ca talyst. For synthesizing the 3',6-di-O-sulfogalabiose, however, a trichloro acetimidate donor was superior (52%) to the pentenyl one (30%). (C) 2001 El sevier Science Ltd. All rights reserved.