Peropyrenes are a class of polycyclic aromatic hydrocarbons (PAHs) with seven fused benzene rings that are under investigation as components within light-harvesting, light-emitting, and charge-transporting materials, with the photonic property of singlet fission as a particular interest. Traditional methods for preparing peropyrene and similar PAH structures from phenalenone or annelated-phenalenone precursors with low-valent metal reagents (Zn or Ti) have required harsh conditions (temperatures >300 deg. Celsius) and/or prolonged reaction times (several days) and give low yields. Additionally, the mechanism for peropyrene formation within these conditions is not known but is assumed to proceed through radical intermediates. We have discovered new, higher-yielding conditions for the formation of peropyrene and substituted peropyrene derivatives via conjugate addition to phenalenone precursors. Addition of boronate, silane, and hydride nucleophiles and the peropyrene products as determined by single-crystal X-ray diffraction studies will be presented, as well as proposed mechanisms for the reactions.

New synthesis of peropyrenes by conjugate addition to phenalenone precursors

247th National Meeting (2014)

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