Palladium‐Catalyzed Cyclization of a Pyryne Precursor to Higher Pyrenylenes

The palladium catalyzed cyclotrimerization of ortho‐silylaryl triflates as aryne precursors is meanwhile an established method to synthesize polycyclic aromatic hydrocarbons (PAHs) with triphenylene cores. During the palladium‐catalyzed reaction of a pyrene with an o‐silylaryl triflate moiety in the K‐region higher homologues with central eight‐ and ten‐membered rings (the pyrenylenes) were found, besides the expected trimer and a protocol was developed to isolate all members of this series. This unprecedented new class of PAHs was fully investigated by all means, including X‐ray diffraction of single‐crystals, UV/Vis and fluorescence spectroscopy and theoretical calculations. Supported by density‐functional theory (DFT) calculations, a mechanism of all higher cyclooligomers is proposed. By palladium‐catalyzed oligomerization reactions of pyrene‐based o‐trimethylsilyl triflates, larger cyclic pyrenylenes were formed with up to 10‐membered rings as has been unambiguously characterized by SCXRD. Furthermore, the underlying reaction mechanism has been studied by quantum chemical calculations.