Highly stereoselective 1,4-conjugate addition of organocopper reagents to methyl α-D-glucopyranoside derivatives tethering an unsaturated ester moiety at C-4 or C-6

(formula presented) The 1,4-conjugate additions of a variety of organocopper reagents to some 4-O-crotonyl derivatives of methyl α-D-glucopyranoside proceeded with a high level of diastereochemical induction to provide the adducts carrying a β-substituted butanoic ester at C-4. The 1,4-conjugate addition to a 6-O-crotonyl derivative afforded the adduct with reverse configuration at the β-carbon' to that obtained from the 4-O-crotonyl derivatives.