Revisiting the armed-disarmed concept rationale: s-benzoxazolyl glycosides in chemoselective oligosaccharide synthesis

reaction: see text]. It has been discovered that 2-O-benzyl-3,4,6-tri-O-acyl SBox glycosides are significantly less reactive than even "disarmed" peracylated derivatives. This finding has been applied to the synthesis of various oligosaccharides, the monomeric units of which are connected via cis-cis, trans-cis, and cis-trans sequential glycosidic linkages. Two-stage activation of the armed (benzylated) donor over moderately (dis)armed (acylated) and, subsequently, over disarmed (2-O-benzyl-3,4-O-diacylated) acceptor has also proven to be feasible.