Multiple arylation of alkyl aryl ketones and α,β-unsaturated carbonyl compounds via palladium catalysis

Alkyl (ethyl to butyl) aryl ketones have been found to undergo multiple arylation on the alkyl chains accompanied by oxidative unsaturation upon treatment with excess aryl bromides in the presence of a palladium catalyst and a base. In the case of phenyl propyl ketones, for example, the arylation occurs up to five times on the α-and γ-positions as well as the ortho-position of the phenyl ring to give 1-(biphenyl-2-yl)-2,4,4,4-tetraphenyl-2-buten-1-ones along with other arylation products. A number of α,β-unsaturated carbonyl compounds are also arylated multiply on the α- and γ-positions.