Catalytic tandem addition route to γ,δ-unsaturated carbonyls

Divalent palladium catalysed tandem addition of lithium halides to alkynes and α,β-unsaturated carbonyl compounds gives δ-halo-γ,δ-unsaturated carbonyls in high yield and good stereoselectivity, the key step being the halide assisted protonolysis of the carbon–palladium bond following halopalladation and carbon–carbon double bond insertion.