Green Synthesis of 3-Alkylidenefuran-2-ones by Palladium-Catalyzed Cyclocarbonylation of Aryl Iodides with Benzyl Acetylenes in 2-MeTHF

A novel, highly efficient heterogeneous palladium-catalyzed carbonylative cyclization of aryl iodides and benzyl acetylenes has been developed under an atmospheric pressure of CO. The reaction proceeds smoothly in a bioderived solvent 2-methyltetrahydrofuran (2-MeTHF) at 50 degrees C using an MCM-41-anchored bidentate phosphine palladium complex [Pd(OAc)2-MCM-41-P,P] as catalyst with DiPEA as base, delivering a wide variety of 3-alkylidenefuran-2-ones in good to excellent yields. The Pd(OAc)2-MCM-41-P,P complex can be easily recovered by a simple centrifugation and recycled more than ten times without any remarkable loss of catalytic activity. The present method not only avoids the use of toxic solvents such as benzene, toluene and THF, but also addresses the key problem of expensive palladium catalyst recovery and recycle, thus preventing palladium contamination in the final product. A general, efficient and practical method for the synthesis of 3-alkylidenefuran-2-ones has been developed from readily accessible aryl iodides and benzyl acetylenes via a recyclable palladium-catalyzed carbonylative coupling reaction in a green solvent 2-MeTHF. The reaction proceeds smoothly under a CO atmosphere and mild conditions, yielding a wide range of furanones in good to excellent yields.image