|
|||||
|
|
A 3,4‐trans‐Fused Cyclic Protecting Group Facilitates α‐Selective Catalytic Synthesis of 2‐Deoxyglycosides |
|
| Authors: | Dr Edward I Balmond Dr David Benito‐Alifonso Dr Diane M Coe Prof Roger W Alder Dr Eoghan M McGarrigle Dr M Carmen Galan |
| Institution: | 1. School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS (UK);2. GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY (UK);3. Centre for Synthesis and Chemical Biology, UCD School of Chemistry & Chemical Biology, University College Dublin, Belfield, Dublin 4 (Ireland) |
| Abstract: | A practical approach has been developed to convert glucals and rhamnals into 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. |
| Keywords: | conformation analysis homogeneous catalysis glycosides protecting groups synthetic methods |