A reaction mixture of β,γ-unsaturated ketone and BF3·OEt2 in CH3OH was stirred at room temperature and β-methoxy ketone was produced in high yield. The β-amino ketone was obtained as the major product from a reaction mixture of β,γ-unsaturated ketone, AlCl3 and Ts-NH2 in CH2Cl2 at room temperature. This Lewis acid promoted β-substitution reaction mechanism was proposed as that the process occurred via in situ isomerization of β,γ-unsaturated ketone to α,β-unsaturated ketone followed by the 1,4-addition reaction.