A 3,4-<i>trans</i>-Fused Cyclic Protecting Group Facilitates α-Selective Catalytic Synthesis of 2-Deoxyglycosides
作者:Edward I. Balmond、David Benito-Alifonso、Diane M. Coe、Roger W. Alder、Eoghan M. McGarrigle、M. Carmen Galan
DOI:10.1002/anie.201403543
日期:2014.7.28
disaccharides or glycoconjugates with high α‐selectivity and yields (77–97 %) using a trans‐fused cyclic 3,4‐O‐disiloxane protecting group and TsOH⋅H2O (1 mol %) as a catalyst. Control of the anomeric selectivity arises from conformational locking of the intermediate oxacarbenium cation. Glucals outperform rhamnals because the C6 side‐chain conformation augments the selectivity.