Diastereo- and Enantioselective Synthesis of α,β-Disubstituted γ-Bisalkoxycarbonyl Sulfonates

The asymmetric synthesis of alpha,beta-disubstituted gamma-bisalkoxycarbonyl sulfonates is reported. The synthesis is based on the Michael addition of a lithiated enantiopure sulfonate bearing a cheap chiral sugar auxiliary to Knoevenagel acceptors. The reaction proceeds with high asymmetric inductions (ds = 69-96%) and good yields (62-79%). The absolute configuration was determined by Xray crystal-structure analysis.