A new catalytic activity of antimony(III) chloride in palladium(O)-catalyzed conjugate addition of aromatics to alpha, beta-unsaturated ketones and aldehydes with sodium tetraphenylborate and arylboronic acids

The arylation of enones and enals by arylboron compounds in the presence of SbCl3 with a Pd catalyst yields the corresponding Michael-type conjugate addition compounds. The absence of SbCl3 leads to Heck-Type substitution products. Arylation proceeds through the formation of an arylpalladium species obtained by oxidative addition between Pd(0) and a C-B bond. This arylpalladium intermediate contains a carbonyl oxygen, which coordinates with SbCl3 to form an antimony enolate and finally the end products.