Unprecedented Highly Stereoselective α- and β-C-Glycosidation with Chiral Titanium Enolates

[reaction: see text] Lewis acid mediated addition of chiral titanium enolates to glycals provides either alpha- or beta-1'-methyl-substituted C-glycosides. This highly stereoselective methodology permits the modular preparation of three of the four possible diastereomers.