The palladium-catalysed conjugate addition type reaction of arylmercury compounds with α,β-unsaturated ketones in a two-phase system

Pd-catalysed reaction of arylmercury compounds with α,β-enones in an acidic two-phase system provides a mild and selective way to β-aryl ketones. The present conjugate addition type reaction may accommodate a wide variety of functional groups. Thus, aryl units containing electron-donating and electron-withdrawing substituents such as -Me, -Cl, -CHO, -COMe, -COOMe, -COOH, -OH, -OMe, -NHCOMe and -NO₂ were successfully transferred to the β C atom of benzalacetone. A number of α,β-enones were also treated with 3-formylphenyl mercury chloride to give the corresponding β-(3-formylphenyl) derivatives. The main limitation seems to arise from steric hindrance in the starting α,β-enonic system. Substituents in the aryl moiety of the organomercury compounds were found to affect the transmetalation step in the direction expected for a rate determining σ-complex formation.