The reaction of vanillin with ethyl acetoacetate using ammonium acetate as catalyst was investigated. The reaction yielded four compounds, α,β-unsaturated ketone 1, 4H-pyran 2, symmetrical pyrylium salt 3 and asymmetrical pyrylium salt 4. Studying necessity of solvent and catalyst, the result showed that acetic acid is the most suitable solvent and ammonium acetate is required to complete the reaction. As the result, I have proposed that reaction undergoes via competition between 1,2-addition and 1,4-addition of the second nucleophile and then cyclization. The structures of products were confirmed by NMR spectroscopy and X-ray crystallography