An enantioselective catalytic approach to syn deoxypropionate units combining asymmetric Cu-catalyzed 1,6- and 1,4-conjugate addition

摘要

A novel iterative approach to the synthesis of the naturally ubiquitous syn deoxypropionate motif is reported. The route comprises a new Horner-Wadsworth-Emmons reagent to prepare α,β,γ,δ- bisunsaturated thioesters. Next, two Me-substituents are introduced in high yield, regio- and enantioselectivity using sequential asymmetric Cu-catalyzed 1,6-conjugate addition, base-catalyzed olefin isomerization and Cu-catalyzed enantioselective 1,4-conjugate addition. After reduction to the aldehyde these transformations can be repeated to install three or more Me groups with a syn 1,3-relationship.