863642-51-7Relevant articles and documents
Stereoselective C-glycosylation reactions of ribose derivatives: Electronic effects of five-membered ring oxocarbenium ions
Larsen, Catharine H.,Ridgway, Brian H.,Shaw, Jared T.,Smith, Deborah M.,Woerpel
, p. 10879 - 10884 (2007/10/03)
The factors controlling the highly α-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 oxocarbenium ions display the C-3 alkoxy group in a pseudoaxial orientation to maximize electrostatic effects. To a lesser extent, the C-2 substituent prefers a pseudoequatorial position, and the alkyl group at C-4 has little influence on conformational preferences. In all cases, the product was formed by stereoelectronically preferred inside attack on the lowest energy conformer.
