Synthesis of α-aryl enaminones through reactions of β-aryl enones with benzyl azide

Reaction of benzalacetones and dibenzalacetones with benzyl azide promoted by BF3·OEt2 afforded Z and E densely substituted acyclic α-aryl enaminones in 21–95% yield. For benzalacetones major Z-isomers were obtained, while E-isomers were the tendency for dibenzalacetones. The synthesis involves domino 1,3-dipolar cycloaddition and 1,2-aryl migration, and is the first metal free practical alternative to the preparation of acyclic α-aryl enaminones from commercially available or easily prepared starting materials.