Synthesis of aromatic aldehydes by organocatalytic [4+2] and [3+3] cycloaddition of α,β-unsaturated aldehydes

Organocatalytic inter- and intramolecular [4+2] and [3+3] cycloadditions of alpha,beta-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. (c) 2007 Elsevier Ltd. All rights reserved.