A novel tandem transetherification—intramolecular hetero Diels–Alder reactions for construction of fused heterocycles

β-Alkoxy-substituted α,β-unsaturated carbonyl compounds activated with an additional electron-withdrawing substituent undergo a facile tandem transetherification/intramolecular hetero Diels–Alder reactions when reacted with δ,ε-unsaturated alcohols under thermal conditions. These reactions are stereoselective producing the corresponding functionalized hydropyranopyran derivatives in good yields.