Preparation of phenalenes and hydronaphthacenes through tandem alkyne Fischer–carbene complex coupling and inter- or intra-molecular Diels–Alder reactions

The rapid construction of phenalenes through the reaction of 8-alkynyltetralones with Fischer–carbene complexes followed by either an inter- or intra-molecular Diels–Alder reaction is presented. As a showcase of the synthetic utility of this process, the rapid construction of polycyclic ring systems containing the tetracycline core has been demonstrated through an iterative application of this reaction sequence.