Heterogeneous metallo-organocatalysis for the selective one-pot synthesis of 2-benzylidene-indoxyl and 2-phenyl-4-quinolone

One-pot tandem heterogeneously catalyzed procedures for the selective synthesis of 2-benzylidene-indoxyl and 2-phenyl-4-quinolone have been developed. For this purpose, heterogeneous palladium-, amine-, and phosphine-catalysts were prepared by post-synthetic grafting onto SBA silica. The state of the hybrid materials was characterized using a wide variety of molecular and solid-state techniques. These materials exhibit high activities as 2-benzylidene-indoxyl was obtained in 81% yields through {[Pd]@SBA-15+PPh3} catalysis while 2-phenyl-4-quinolone was prepared by a fully heterogeneous {[Pd]@SBA-15+[AMINE]@SBA-3} protocol in 61–75% isolated yield. For the later, we demonstrated that the catalysts mixture could be reused up to three runs without strong deactivation.