Synthesis of aromatic (E)- or (Z)-α,β-unsaturated amides with total or very high selectivity from α,β-epoxyamides and samarium diiodide

Highly stereoselective synthesis of aromatic alpha,beta-unsaturated amides was achieved by treatment of aromatic alpha,beta-epoxyamides with samarium diiodide. The starting compounds 1 and 3 are easily prepared by the reaction of enolates derived from alpha-chloroamides with carbonyl compounds at -78 degreesC. A mechanism to explain this transformation is proposed.