The 2-(allyloxy) phenyl acetyl ester as a new relay protecting group for oligosaccharide synthesis

The 2-(allyloxy) phenyl acetyl group can be removed by a relay approach using Pd(PPh3)4 in combination with proton sponge, conditions that do not affect acetyl, benzoyl and levulinoyl esters. On the other hand, the acetyl and levulinoyl ester could be cleaved without removal of the 2-(allyloxy) phenyl acetyl group. The new protecting group is compatible with glycosylations and can perform efficiently neighboring group participation leading to the exclusive formation of 1,2-trans glycosides.