Coupling Reactions Catalyzed With Phosphine Ligands With Cobaltocenium Backbone And Synthesis, Properties Of Their Derivatives

The transition metal-catalyzed cross-coupling reaction is one of the most effective methods for construction of carbon-carbon bonds and has found widespread use in organic synthesis. However, the use of inflammable, volatile and toxic organic solvents, using ionic liquid or water in place of the traditional organic solvents have been the particular attention, meanwhile, because of the high price of palladium catalyst, for the view of economy, using inexpensive metal in place of palladium is a significant strategy. Phosphine ligands with cobaltocenium backbone can be used in ionic liquids. We have studied on the synthesis, electrochemistry of phosphine ligands with cobaltocenium backbone and their derivatives, and the catalytic properties of phosphine ligands with cobaltocenium backbone and coupling reactions catalyzed by low toxic, inexpensive copper salt. The main results are as follows:1. The Sonogashira and Heck reactions catalyzed with phosphine ligands with cobaltocenium backbone in the ionic liquid have been investigated. It showed that the Sonogashira reaction of aryl iodide with terminal acetylenes in ionic liquid was performed effectively catalyzed with the catalyst derived from the phosphine 2-1 and palladium chloride. The catalyst can be recycled and reused for nine times. The Heck reaction of aryl iodides with olefins was performed effectively catalyzed with the catalyst derived from ligand 2-1 and Pd(dba)₂, the catalyst loading can be down to 0.2 mol%, the catalyst can be recycled and reused for five times.2. The Sonogashira, Suzki and Heck reactions catalyzed with phosphine ligands with cobaltocenium backbone in pure water have been investigated. It showed that the Sonogashira reaction of aryl bromides with terminal acetylenes was performed smoothly catalyzed with the catalyst derived from the phosphine ligand 2-1 and Pd(dba)₂, and the catalyst can be reused three times. The Suzuki reaction of aryl bromides with phenyl boronic acid and the Heck reaction of aryl iodides with olefins can be catalyzed with the catalyst derived from the phosphine ligand 2-1 and Pd(dba)₂.3. The Sonogashira reaction in water using cheap, readily available triphenylphosphine as ligand has been studied. It showed that the Sonogashira reaction of aryl bromides with terminal acetylenes was performed effectively in pure water, catalyzed with the catalyst derived from triphenylphosphine and palladium chloride in the absence of copper salt. And the Sonogashira reaction using copper in place of palladium has been studied, the result showed that the Sonogashira reaction of aryl iodides with terminal acetylenes can be performed effectively with the catalyst derived from triphenylphosphine and copper(I) iodide in the absence of phase-transfer catalyst.4. A series of compounds have been synthesized using diphosphine (2-1, 3-1) and monophosphine (4-1) as starting materials. The Structures for these compounds were fully characterized by NMR and elemental analysis, some of these compounds were determined by X-ray diffraction. It showed that the cis complexes were obtained when the diphosphine ligands (2-1, 3-1) coordinated to Pd or Pt, and the trans complexes were obtained as to monophos- phine ligand (4-1). The coordinating modes have close relation to the anions when diphosphine ligand (2-1) coordinates to silver salt, mononuclear complexes were obtained as to NO₃^-or NO₂^-, otherwise dinuclear complexes bridging united by anion were obtained as to Cl^-,Br^-,PhCO₂^-,CF₃CO₂^-. Zigzag long-chain polymer interlinked by NO₃^- was obtained by reation of monophosphine ligand 4-1 with AgNO₃, but a cluster was obtained by reation with CuBr. And electrochemical properties of phosphine ligands with cobaltocenium backbone and their complexes have been described. The results showed that the redox potentials of cobaltocenium(â…¢/â…¡) were all shifted positively for the complexes, the maximum shift(E_1/2) is +422 mV for 4-6.5. Chalcogenide compounds of diphosphine (2-1, 3-1) and monophosphine (4-1) have been synthesized by oxadizing P (â…¢) to P(â…¤), and these compounds were confirmed by NMR, Elemental analysis and X-ray diffraction, and their electrochemical properties were described. The results showed the redox potentials of cobaltocenium(â…¢/â…¡) were all shifted positively for the oxides, the maximum shift(E_1/2) is +528 mV for 5-3.