Iodine-Mediated C═C Double Bond Cleavage toward Pyrido[2,1-]quinazolinones.

A transition-metal-free C═C double bond cleavage reaction employing molecular iodine is described. In the presence of KCO as the base, I-mediated C═C bond cleavage followed by intramolecular annulation of -(2-vinylaryl)pyridin-2-amine substrates produces pyrido[2,1-]quinazolinones and related heterocyclic compounds. This reaction can be completed on a gram scale and has been successfully applied to the synthesis of compounds with important biological properties, including efflux pump inhibitory and antiallergic activities.