The synthesis of 4-arylphenalenones revisited

The synthesis of 4-phenylphenalenones, a group of phytoalexins exclusive from Musa acuminata (bananas), has been revisited to extend the scope of the derivatives that can be prepared. The discovery that 4-methoxyphenalenone participates in a selective substitution reaction allowed the preparation of 4-bromophenalenone, which proved to be an efficient substrate for Suzuki cross-couplings. The results solve the previously uncovered problem of preparing electron-rich 4-heteroarylphenalenones and provide a general synthesis of this type of phytoalexins.