| Popis: |
A novel organocatalytic method for the stereoselective synthesis of highly substituted cyclopropanes is reported. The Michael adducts, generated through the addition of α-substituted cyanoacetates to easily accessible vinyl selenones catalyzed by a bifunctional ureidic catalyst, smoothly cyclize by intramolecular alkylation induced by a de-ethoxycarbonylation process. The one-pot sequence generates cyclopropanes bearing adjacent tertiary and quaternary stereocentres as single Z-isomers in moderate to high yields and good enantiomeric excesses. |
