Five-membered cyclopalladated complex containing bidentate phosphine ligands; Synthesis,characterization, and highly efficient Suzuki cross-coupling reactions

A nonsymmetric phosphorus ylide and its palladium(II) complex have been synthesized as potential catalytically active compounds. The reaction of 1 equiv nonsymmetric phosphorus ylide, Ph₂PCH₂PPh₂C(H)C(O)PhBr with Pd(dppe)Cl₂], followed by treatment with 2 equiv AgOTf led to (dppe)Pd(Ph₂PCH₂PPh₂C(H)C(O)PhBr)](OSO₂CF₃)₂, which contains a five-membered P,P chelate ring on one side and a five-membered P,C chelate ring on the other side. The palladium complex was synthesized and investigated by fourier transform infrared spectroscopy (FT-IR), UV–visible, multinuclear (¹H, ³¹P and ¹⁹F) nuclear magnetic resonance (NMR), and electrospray ionisation-mass spectroscopic techniques. FT-IR and ³¹P NMR studies revealed that the phosphorus ylide is coordinated to palladium via the terminal phosphorus (P_c) of the ylide and methene group (CH). Suzuki reactions for varying aryl halides using the cyclopalladated complex as an efficient catalyst were performed. Various aryl halides were coupled with arylboronic acids in DMF, under air, in the presence of 0.001?mol% of the homogeneous catalyst to afford the corresponding cross-coupled products in good to excellent yields.