Copper-catalyzed Coupling Reaction Research Articles

A convenient route to unsymmetrical conjugated diynes

Various unsymmetrical conjugated diynes can be prepared in good to excellent isolated yields by copper catalyzed coupling reaction of terminal alkynes with 1-iodo alkynes in pyrrolidine. In the case of 1-bromo alkynes, the presence of a catalytic amount of PdCl 2(PPh 3) 2 improved the yield of coupling products.

Synthesis and transition metal catalysed reactions of 1-Ureido-3-propargyl-2,3-dihydropyrrol-2-ols, 1-ureido-3-propargylpyrroles and 1-ureido-3-propargyl-3-phosphono-1 H-pyrrol-2(3 H)-ones

The title compounds were obtained by reaction of conjugated azoalkenes with activated methinic derivatives bearing a propargylic residue. 1-Ureido-3-propargyl-2,3-dihydropyrrol-2-ols gave in the presence of Cu(I) catalyst the 2,5-dimethyl-3-ethoxycarbonyl-4-(2-oxopropyl)-1-(N′-phenylureido)-pyrrole, while in the presence of Pd(0) or Au 3+ the 3,6-dimethyl-5-ethoxycarbonyl-4-propargyl-1,4-dihydropyridazine was obtained by ring opening and ring expansion reaction. The propargylic side chain of 1-ureido-3-propargylpyrroles and 1-ureido-3-propargyl-3-phosphono-1 H-pyrrol-2(3 H)-ones was functionalised by means of palladium and/or copper catalysed coupling reactions with aryl or vinyl triflates and halides.

Copper-catalyzed coupling reaction of aryl and vinyl halides with terminal alkynes

Coupling reaction of aryl and vinyl halides with terminal alkynes using a catalyst system of copper(I) iodide - triphenylphosphine proceeds efficiently in the presence of potassium carbonate to give the corresponding unsymmetrical acetylenes in good yield.

Protonation of tetranuclear oxo(chloro)pyridinecopper(II) complexes by HBF 4 in nitrobenzene

Tetrafluoroboric acid (HBF 4) and triethylamine (Et 3N) have been added consecutively to solutions of tetranuclear oxocopper(II) complexes (μ 4-O)py 3Cu 4Cl 4O ( Ia), (μ 4-O)py 4Cu 4Cl 4O ( Ib), (μ 4-O)py 3Cu 4Cl 6 ( IIa), (μ-O) 2N 4Cu 4Cl 4 ( IIIa) and (μ 4-O)N 4Cu 4Cl 6( IVa) in nitrobenzene at 25 °C to examine their proton basicities. Here, py is pyridine and N is N, N-diethylnicotinamide. The reactions were assigned from spectral and conductivity data. We conclude that the μ 4-oxo groups of IIa and IVa are reversibly monoprotonated by HBF 4 and are less basic than Et 3N. Further addition of HBF 4 apparently removes the central μ 4-oxo group of IIa and IVa as H 3O + and then protonates coordinated py and N. Complexes Ia, Ib and IIIa are irreversibly monoprotonated at their respective oxo groups, which are more basic than Et 3N. The protonation sequence for Ia consists of loss of its terminal oxo group Cu vO as H 3O +, followed by loss of coordinated py as pyH +. The sequence for Ib is the same except that py coordinated at the v site of Ib is protonated in preference to py at sites x. The μ 4-oxo group of Ia and Ib and the OH groups of diprotonated IIIa are less basic than their respective ligands py and N. Implications of the results on the mechanisms of copper-catalyzed phenolic oxidative coupling reactions are considered.

Effects of transmetalation on the mechanisms of copper-catalyzed phenolic oxidative coupling reactions

The mechanism of initiation of phenolic oxidative coupling by the tetranuclear copper( I) complex [pyCuCl] 4 is affected by transmetalation. [pyCuCl] 4 is stoichiometrically transmetalated by equimolar (M(NS) 2 reagents (M is Co, Ni, Cu or Zn) at room temperature in nitrobenzene under N 2 to give equimolar solutions of air-sensitive complexes py 3Cu 3M(NS)Cl 4 ( IIa-d, respectively) and py and 1 mol of insoluble Cu(NS)(s). The corresponding reaction with equimolar Co(NS) 3 gives equimolar solutions of py 3Cu 3Co(NS) 2Cl 4 ( III) and py and 1 mol of Cu(NS)(s). Here, py is pyridine and NS is monoanionic S-methyl isopropylidenehydrazinecarbodithioate. Second- order reduction of O 2 by [pyCuCl] 4 gives the tetranuclear oxocopper(II) complex (μ- 4-O)py 4Cu 4Cl 4O ( Ib). Reduction of O 2 by IIc in the presence of equimolar py gives Ib and the disulfide co-product N 2S 2. The corresponding reductions of O 2 by IIa, IIb, IId and III give products py 3CuMCl 4O 2 ( IVa, IVb, IVd and IVa, respectively) and N 2S 2. Insertion of O 2 through the Cl 4 cores of the reductants is the rate-determining step in each system. However, different product core structures are indicated by different spectral sensitivity to oxidation co-product N 2S 2 and by different rate laws for their oxidation of 2,6-dimethylphenol (DMPOH) to the corresponding diphenoquinone. These core structures apparently contain either a weakly basic CuOM unit (in IVa and IVb) or a strongly basic Cu v O unit (in Ib and IVd). As a result, the rates of oxidation of DMPOH by Ib and IVd are independent of [DMPOH]. Opening of the CuOM unit to give a weakly basic site M v O is proposed to explain induction periods in the IVa, IVb/DMPOH systems, which then proceed at rates which are proportional to [DMPOH]. The origin of different py 3, 4Cu 3MCl 4O 2 product core structures is discussed.

Synthesis of functionalized aliphatic aldehydes via a copper-catalyzed Grignard coupling reaction

Synthesis of functionalized aliphatic aldehydes via a copper-catalyzed Grignard coupling reaction

Copper Promoted Coupling Reaction I. Phenylation of O-H and N-H Compounds with C6H5X by Using Copper Catalyst Itself as the Acceptor of HX Released

Abstract The copper catalyzed coupling reaction of O-H and N-H compounds with aryl halides ArX leads to the replacement of the hydrogen by the aryl group:1 Addition of bases such as K2CO3 and KOH as the acceptor of HX released is necessary for the reaction to proceed, and sometimes, instead of the O-H and N-H compounds, use of their salts (e.g., potassium phenolate and potassium phthalimide) as the starting material is required.