O-Glycosyl Donors
3.4
577
⊡ Scheme 7
Intermolecular halonium-ion transfer
⊡ Scheme 8
Halonium ion transfer: a key factor in armed-disarmed couplings
(56→57→58). By corollary, the inherent reactivity of the glycosyl donors is thus revealed
in the final product distribution. If the acceptor functionality is located in the less reactive
component, selective glycosylations take place leading to a specific disaccharide.
2.3.4 Torsional Disarming of NPGs
Fraser-Reid and co-workers found that widely used cyclic acetals also affected anomeric
reactivity [41]. They showed that these reactivity differences could be applied to an armed-
3.4
577
⊡ Scheme 7
Intermolecular halonium-ion transfer
⊡ Scheme 8
Halonium ion transfer: a key factor in armed-disarmed couplings
(56→57→58). By corollary, the inherent reactivity of the glycosyl donors is thus revealed
in the final product distribution. If the acceptor functionality is located in the less reactive
component, selective glycosylations take place leading to a specific disaccharide.
2.3.4 Torsional Disarming of NPGs
Fraser-Reid and co-workers found that widely used cyclic acetals also affected anomeric
reactivity [41]. They showed that these reactivity differences could be applied to an armed-