Novel Brønsted Acid Catalyzed C-C Bond Activation and α-Alkylation of Ketones

A novel approach for the <i>α</i>-alkylation of ketones was developed using Brønsted acid-catalyzed C-C bond cleavage. Both aromatic and aliphatic ketones reacted smoothly with 2-substituted 1,3-diphenylpropane-1,3-diones to afford <i>α</i>-alkylation products with high yields and with excellent regioselectivity, in which the 1,3-dicarbonyl group acted as a leaving group in the presence of the catalyst TfOH. Mechanism experiments showed that the <i>β</i>-C-C bond cleavage of diketone and the shift of the equilibrium towards the enol formation from ketone are driving forces that induce the desired products.