Carbamate‐Directed peri ‐CH Alkynylation: Application to the Synthesis of Zethrenes and Pyranthrenes

The Rh(III)‐catalyzed regioselective alkynylation of 1‐pyrenyl and 1‐naphthyl carbamates with bromoacetylenes allows for the selective introduction of an alkyne at the peri position of readily available amino‐substituted polycyclic aromatic hydrocarbons (PAHs). Interestingly, depending on the coupling partner of choice, insertion of the alkyne can occur with opposite regioselectivity after CH functionalization, leading to either alkynylation or amine cyclization. We have applied this methodology for the synthesis of new vertically π‐extended zethrene derivatives with two pyrene subunits. Further oxidative cyclodehydrogenation regioselectively forms a hexabenzo[ def, i, lm, qrs, v, yz ]pyranthrene, which has been characterized by electron diffraction.