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.