Selective acetolysis of 6-deoxy-sugar oligosaccharide building blocks governed by the armed–disarmed effect

The effect of the arming–disarming protection in the acetolysis of 6-deoxy-sugar oligosaccharides has been for the first time systematically investigated. Starting from the newly synthesized methyl glycosides, the acetolysis conditions employed here afforded 1-O-Ac oligosaccharides selectively without cleavage of the interglycosidic bonds, if a suitable protecting group pattern was used. Actually, the behavior of armed–disarmed, armed-armed, and disarmed–disarmed 6-deoxy-sugar disaccharides in acetolysis reactions was investigated: the results fit well with the prediction made on the basis of the armed–disarmed effect.