Stereoselective <i>C</i>-Glycosylation Reactions of Ribose Derivatives: Electronic Effects of Five-Membered Ring Oxocarbenium Ions
作者:Catharine H. Larsen、Brian H. Ridgway、Jared T. Shaw、Deborah M. Smith、K. A. Woerpel
DOI:10.1021/ja0524043
日期:2005.8.1
The factors controlling the highly alpha-selective C-glycosylation of ribose derivatives were determined by examining the stereoselective reactions of 18 ribose analogues differing in substitution at C-2, C-3, and C-4. The lowest energy conformers of the intermediate oxocarbeniumions display the C-3 alkoxy group in a pseudoaxial orientation to maximize electrostatic effects. To a lesser extent, the