Solid-State Generation of Diarylisonaphthofuran and Its Mechanochemical Diels-Alder Reaction with Epoxynaphthalene

A solid-state method was developed for generating diarylisonaphthofurans from 1,3-diaryl-1,3-dihydronaphthofuranols. The generated reactive molecules were stable in the solid state and could be stored without any extra precautions. X-ray diffraction analysis revealed a typical quinoidal structure. Furthermore, the mechanochemical Diels-Alder reaction of 1,3-diarylisonaphthofurans with epoxynaphthalenes afforded synthetically attractive diepoxypentacenes.

Isoacenofuran: a novel quinoidal building block for efficient access to high-ordered polyacene derivatives

Herein, a simple and practical method for generating isoacenofuran, a new π-extended quinoidal building block, was developed. A three-step protocol involving double nucleophilic additions of alkynyllithiums to acene-2,3-dicarbaldehyde, mono-oxidation, and acid-promoted cyclization enables the generation of the target molecule, which is trapped by a dienophile to produce highly condensed acenequinones. Further transformations by double nucleophilic additions of alkynyllithium to hexacenequinone, followed by reductive aromatization, produce tetraalkynylhexacenes with a remarkably higher stability than that of the previously reported substituted hexacenes.

Intramolecular benzoallene–alkyne cycloaddition initiated by site-selective SN2′ reaction of epoxytetracene en route to π-extended pyracylene

A new synthetic route to π-extended pyracylene was developed by hydrogen halide promoted cascade reaction of epoxytetracene.