Synthesis of a Doubly Boron‐Doped Perylene through NHC‐Borenium Hydroboration/C−H Borylation/Dehydrogenation

Reaction of an N‐heterocyclic carbene (NHC)–borenium ion with 9,10‐distyrylanthracene forms four B−C bonds through two selective, tandem hydroboration–electrophilic C−H borylations to yield an isolable, crystallographically characterizable polycyclic diborenium ion as its NTf₂]⁻ salt ( 1 ). Dehydrogenation of 1 with TEMPO radical followed by acidic workup yields a 3,9‐diboraperylene as its corresponding borinic acid ( 2 ). This sequence can be performed in one pot to allow the facile, metal‐free conversion of an alkene into a small molecule containing a boron‐doped graphene substructure. Doubly boron‐doped perylene 2 exhibits visible range absorbance and fluorescence in chloroform solution (Φ =0.63) and undergoes two reversible one‐electron reductions at moderate potentials of −1.30 and −1.64 eV vs. ferrocenium/ferrocene in DMSO. Despite sterically accessible boron centers and facile electrochemical reductions, compound 2 is air‐, moisture‐, and silica gel‐stable.