Juan F. Araneda

BN‐Dibenzo[a,o]picenes: Analogues of an Unknown Polycyclic Aromatic Hydrocarbon

Reflecting on synthetic pinnacles: Whereas the parent hydrocarbon is not readily accessible, several examples of BN substituted-dibenzo[a,o]picenes can be prepared in two steps from known starting materials. These non-linear heptacene analogues are water-stable materials. Their preparation utilizes a potentially general method for preparing extended BN analogues of difficult-to-synthesize polycyclic aromatic hydrocarbon frameworks.

Photochemical Synthesis of a Ladder Diborole: A New Boron‐Containing Conjugate Material

Climbing the ladder: Reductive cyclization of alkynyl haloboranes lead to the bis-benzocycloborabutylidene rather than the expected ladder diborole, despite the former being much less thermodynamically favored. Photochemical conversion to the ladder diborole was, however, quite facile upon irradiation at 254 nm.

Bronsted acid-catalyzed skeletal rearrangements in polycyclic conjugated boracycles: a thermal route to a ladder diborole

The dibenzodiboracyclobutylidene 1 was recently shown to undergo photochemical rearrangement to the more thermodynamically stable dibenzodiborapentalene 2. In order to discover a more efficient thermal route for this isomerization, the redox chemistry of both 1 and 2 was explored. Radical anions can be formed and characterized by EPR spectroscopy by one electron reduction using potassium graphite. The [Cp*2Co]+ salt of the radical anion of 2 was characterized by X-ray crystallography. The dipotassium salts 1K2 and 2K2 can be prepared by using two equivalents of potassium naphthalenide; both were fully characterized. It was found that smooth rearrangement of 1K2 to 2K2 is mediated by weak Bronsted acids such as tert-butanol or 2,6-dimethylphenol; a mechanism based on similar rearrangements in the isoelectronic neutral all-carbon framework is proposed.