β‐Imino‐meso‐tetraphenylporphyrin Derivatives in Hetero‐Diels−Alder Reactions

Two types of β‐imino‐meso‐tetraphenylporphyrin derivatives were used as heterodienes in Diels−Alder reactions with electron‐rich dienophiles. These reactions were catalysed by lanthanum triflate. Depending on the starting imine derivative, the products of these reactions are pyrido[2,3‐b]porphyrins or β‐tetrahydroquinoline‐substituted porphyrins. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)