Highly Stereoselective 1,4-Conjugate Addition of Organocopper Reagents to Methyl α-<scp>d</scp>-Glucopyranoside Derivatives Tethering an Unsaturated Ester Moiety at C-4 or C-6<sup>1</sup>
[GRAPHICS]The 1,4-conjugate additions of a variety of organocopper reagents to some 4-O-crotonyl derivatives of methyl alpha-D-glucopyranoside proceeded with a high level of diastereochemical induction to provide the adducts carrying a beta-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 beta-carbon to that obtained from the 4-O-crotonyl derivatives.