Palladium catalyzed reductive decarboxylation of allyl α-alkenyl-β-ketoesters. A new synthesis of (E)-3-alkenones

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%).