Neighboring Group Participation by Other Functional Groups

3 Neighboring Group Participation by Other Functional Groups 

SCHEME 4.3 Use of the picolyl ether for the stereoselective synthesis of 1,2-trans- 

SCHEME 4.4 1,2-Migration of an anomeric participating group to afford a- or 3-deoxyglycosides. 

2-iran.v-pyridinium ion 15 was inert under these conditions and was recovered. Although the activation of glycosyl donors proceeded readily, the unreactive nature of the intermediate pyridinium ions hampered broad applicability of the methodology. 

SCHEME 4.5 1,2-Migration in the stereoselective synthesis of 1, 2-tram (amino)-glyco-sides and 2-deoxyglycosides as reported by (a) Danishefsky, (b) Yu, and (c) Lowary. Ac, acetyl All, allyl Bn, benzyl Bz, benzoyl DTBMP, 2,6-di-fert-butyl-4-mcthyl pyridine TBDPS, ferf-butyldiphenylsilyl THF, tetrahydrofuran TIPS, triisopropylsilyl Tol, 4-tolyl. 

---