The reductive decarboxylation of α-alkenyl derivatives of allyl-β-ketoesters was achieved by use of palladium (0) catalyst generated in situ from Pd (OAc) 2 and PPh3, with triethylammonium formate as the hydride source, in THF. The reaction proceeds smoothly and cleanly, with linear alkenyl derivatives of allyl-β-ketoesters, to afford (E)-3-alkenones in good to excellent yields (73–92%) and high stereoselectivity (> 98%).