Stereoselectivity in the Lewis acid mediated reduction of ketofuranoses

J Org Chem. 2015 May 1;80(9):4553-65. doi: 10.1021/acs.joc.5b00419. Epub 2015 Apr 13.

Abstract

The Lewis acid mediated reduction of ribose-, arabinose-, xylose-, and lyxose-derived methyl and phenyl ketofuranoses with triethylsilane as nucleophile was found to proceed with good to excellent stereoselectivity to provide the 1,2-cis addition products. The methyl ketoses reacted in a more stereoselective manner than their phenyl counterparts. The stereochemical outcome of the reactions parallels the relative stability of the oxocarbenium ion conformers involved, as assessed by calculating the free energy surface maps of their complete conformational space. The Lewis acid mediated reduction allows for a direct synthesis of C-glycosides with predictable stereochemistry.