Sulfur dioxide-mediated syntheses of polyfunctional alkenes and (E,Z)- and (E,E)-2,4-dien-1-ones.

Efficient methods for the stereoselective synthesis of polyfunctional (E)- and (Z)-alkenes and conjugated (E,E)- and (E,Z)-dienones are presented. They rely upon one-pot, four-component processes that condense 1-oxy-1,3-dienes, silyl enol ethers, SO2, and carbon electrophiles. [structure: see text]