β-Silyl Acrylates in Asymmetric [3 + 2] Cycloadditions Affording Pyrrolidine Azasugar Derivatives.

A highly efficient copper(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with 3-silyl unsaturated esters has been developed, providing elegant access to chiral 3-silylpyrrolidine derivatives bearing contiguous stereogenic centers in moderate-to-excellent yields (up to 99%) with high diastereo- and enantioselectivities (dr up to >99:1; ee up to 96%). Notably, the 3-silylpyrrolidines can easily be converted to pyrrolidine azasugar derivatives with potential biological activities by the reduction of two ester groups and carbon-silicon bond oxidation.