Metal-free regioselective ring expansion reaction of acenaphthenequinone with diazomethanes: A facile one-pot synthesis of phenalenones

Herein, we describe a regioselective ring-expansion reaction of acenaphthenequinone using N-tosylhydrazone as diazo 1,3-dipolar precursor, which can highly efficiently prepare functionalized 3-phenylphenalenones in ethanol solvent. These reactions feature readily available starting materials, transition metal- and oxidant-free, Ecofriendly operations, one-pot syntheses and wide functional group tolerance. Specifically, in the synthesized phenalenones, C-2 and C-3 are substituted by hydroxyl and phenyl has not been reported so far, and the potential biological and physical value of these newly synthesized corresponding products has good application foreground.