Synthesis of Parent Peropyrene and Its Derivatization

We have established a practical and scalable (>1 g) synthesis of peropyrene, dibenzo[cd,lm]perylene, from easily accessible 2,3-dihydro-1H-phenalen-1-one, which was first dimerized via the reductive coupling reaction to form the tetrahydro-biphenalenylidene skeleton consisting of 26 carbon atoms, followed by the oxidative photocyclization reaction giving tetrahydroperopyrene and the final aromatization. The iridium-catalyzed direct borylation reaction on peropyrene was not quite regioselective, giving a mixture consisting of mono- to hexaborylated derivatives even with a controlled amount of the reagents used. Instead, tetrahydro- or octahydroperopyrene turned out to be a suitable substrate for the regioselective borylation to give 2,9-diborylated or 2-(mono)borylated peropyrene, respectively. These borylated peropyrenes were utilized for the synthesis of various peropyrene derivatives, including 2,9-diarylperopyrenes, dimeric peropyrenes, and a peropyrene-based macrocycle, indicating that the borylated peropyrenes are potential intermediates for peropyrene-based optoelectronic materials.