A highly active palladium(II)-bis(oxazoline) catalyst for Suzuki-Miyaura, Mizoroki-Heck and sonogashira coupling reactions in aqueous dimethylformamide

An efficient catalytic system based on a new palladium-bis(oxazoline) (Pd-BOX-1) complex has been developed. The complex Pd-BOX-1 adopts a legless chair-type structure where the distorted square planar [PdN₂Cl₂] moiety and the benzene ring spacer represent the seat and the chair back, respectively. The catalytic activity of Pd-BOX-1 has been investigated in dimethylformamide-water under aerobic and mild conditions in Suzuki-Miyaura coupling reactions of arylboronic acids with aryl iodides, aryl bromides and aryl chlorides, Mizoroki-Heck coupling reactions of aryl halides with styrene derivatives, and Sonogashira coupling reactions of aryl halides with terminal alkynes. A wide range of functional groups as substituents on the arylboronic acids and aryl halides were considered. Pd-BOX-1 demonstrates exceptional air and moisture stability. Of note, the catalyst system based on Pd-BOX-1 shows high recycling ability in Suzuki-Miyaura coupling reactions in dimethylformamide-water without any loss in catalytic activity.