Organocatalytic inter-and intramolecular [4+ 2] and [3+ 3] cycloadditions of α, β-unsaturated aldehydes to give polysubstituted aromatic aldehydes are described. High periselectivity for the cycloadditions, with catalyst effects exerted by l-proline and pyrrolidine–HOAc, as well as cocatalyst, additive effects, has been observed.
