Highly regioselective [3,3] rearrangement of aliphatic allyl vinyl ethers catalyzed by a metalloporphyrin complex, Cr(TPP)Cl

The Claisen rearrangement of simple aliphatic allyl vinyl ethers catalyzed by a metalloporphyrin, Cr(TPP)Cl, is described. The porphyrin-based Lewis acid catalyst can effectively accelerate the rearrangement via a concerted 3,3] pathway with a minimal degree of bond ionization of the substrates, providing the corresponding Claisen products in moderate to high yields and almost perfect regioselectivity at low catalyst loading.