Mg-promoted regio- and stereoselective C-acylation of aromatic alpha,beta-unsaturated carbonyl compounds.

[reaction: see text]. Treatment of aromatic alpha,beta-unsaturated carbonyl compounds with Mg turnings in the presence of acid anhydrides/TMSCl or acyl chlorides in DMF brought about a facile and efficient cross-coupling to give C-acylation products, which are useful 1,4-dicarbonyl compounds, in good to excellent yields in a regio- and stereoselective manner. The reaction may be initiated by electron transfer from magnesium to the substrates.