The tin(IV) chloride-promoted reaction of enoltrimethylsilylethers with α-tributylstannylthioacetals gave β-phenylthio-β-tributylstannylketones, which were easily transformed to β-tributylstannyl-α,β-unsaturated ketones (3) by the treatment with potassium hydride or DBU. On the basis of the results obtained in the study of the reaction of 3 with copper(II) bromide, it was assumed that the present