Recyclable palladium-catalyzed cyclocarbonylation of o-iodoarylcarbodiimides and nucleophiles in bioderived 2-MeTHF towards the formation of 2-heteroquinazolin-4(3H)-ones

Abstract

A new mesoporous SBA-15-immobilized Schiff base and phosphine mixed bidentate palladium(II) complex [SBA-15-N,P-Pd(OAc)₂] was prepared via immobilization of 3-aminopropyltriethoxysilane onto SBA-15, followed by the condensation with 2-(diphenylphosphino)benzaldehyde and then coordination with Pd(OAc)₂. With the use of 4 mol% of SBA-15-N,P-Pd(OAc)₂ as a catalyst, the cascade addition/cyclocarbonylation reaction of o-iodoarylcarbodiimides with nucleophiles proceeded smoothly in bioderived 2-MeTHF at 80 °C with K₂CO₃ as a base under 7 bar of CO to deliver a wide array of 2-heteroquinazolin-4(3H)-ones in good to excellent yields with wide tolerance of functional groups. The SBA-15-N,P-Pd(OAc)₂ complex could be facilely recovered by simple filtration of the reaction mixture and recycled at least eight times without any significant loss of catalytic efficiency.