Pd(0)-Catalyzed Intramolecular "Ylide-Ullmann-Type" Cyclization of Carbonyl-Stabilized Phosphonium Ylides and Access to Phosphachromones by Exocyclic P-C Cleavage.

An unprecedented palladium-catalyzed intramolecular Ullmann-type cyclization of carbonyl-stabilized phosphonium ylides with aryl bromides was successfully developed. Furthermore, a base-promoted chemoselective hydrolysis of exocyclic P-C bond of the corresponding phosphonium salts delivered various phosphachromones. Excellent selectivity and high efficiency and good functional group tolerance were observed.