Synthesis and Diels−Alder Reactions of 1,2-Dimethylene[2.n]metacyclophanes

The Diels−Alder reaction of 1,2-dimethylene[2.n]MCPs (MCP = metacyclophane) with suitable dienophiles followed by aromatization and photoinduced or FeCl₃-induced transannular cyclization afforded phenanthrene-anellated polycyclic aromatic hydrocarbons, which were found to adopt helical chirality in the solid state.