Copper(II)triflate Promoted Highly Chemoselective Rearrangement of Chalcone Epoxides to β-keto Aldehydes

Highly chemoselective rearrangement of chalcone epoxides to β-keto aldehydes using catalytic amount of Cu(OTf)2 (1 mol%) is presented. Copper(II)triflate is a relatively cheap, inexpensive and commercially available catalyst. In this rearrangement selective migration of the acyl group takes place. The presence of an electron donating group on either of the phenyl rings favors the reaction. However, the presence of an electron withdrawing CN group leads to the corresponding β-keto aldehyde, along with an aryl ketone which is obtained through deformylation of the primary product.