Development of an Arming Participating Group for Stereoselective Glycosylation and Chemoselective Oligosaccharide Synthesis

Armed and dangerous: A new armed–disarmed glycosylation strategy (see picture) allows chemoselective introduction of a 1,2-trans glycosidic linkage prior to other linkages through the use of a 2-O-picolyl moiety. This neighbouring group is capable of efficient participation through a six-membered intermediate while retaining the glycosyl donor in the armed state. Bn=benzyl, Bz=benzoyl, Tf=trifluoromethanesulfonyl, Pic=picolyl.