Synthesis and characterizations of N,N′‐bis(diphenylphosphino)‐2‐(aminomethyl)aniline derivatives: application of a palladium(II) complex as pre‐catalyst in Heck and Suzuki cross‐coupling reactions

The reaction of 2‐(aminomethyl)aniline with 2 equivalents of PPh₂Cl in the presence of Et₃N, proceeds in CH₂Cl₂ to give N,N′‐bis(diphenylphosphino)‐2‐(aminomethyl)aniline 1 in good yield. Oxidation of 1 with aqueous H₂O₂, elemental sulfur or gray selenium gave the corresponding oxide, sulfide and selenide dichalcogenides [Ph₂P(E)NHC₆H₄CH₂NHP(E)Ph₂] (E: O, 2a; S, 2b; Se, 2c), respectively. The reaction of [Ph₂PNHC₆H₄CH₂NHPPh₂] with PdCl₂(cod), PtCl₂(cod) and [Cu(MeCN)₄]PF₆ gave the corresponding chelate complexes, PdCl₂1, PtCl₂1 and [Cu(1)₂]PF₆. The new compounds were fully characterized by NMR, IR spectroscopy and elemental analysis. The catalytic activity of the Pd(II) complex was tested in the Suzuki coupling and Heck reactions. The Pd(II) complex catalyzes the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes respectively, in good yields. Copyright © 2009 John Wiley & Sons, Ltd.     

Ligand effects in palladium‐catalyzed Suzuki and Heck coupling reactions

A range of sterically hindered diimine ligands and their palladium (II) complexes were synthesized. These compounds were fully characterized by elemental analysis, ¹H and ¹³C‐NMR spectroscopy. The use of the palladium complexes as catalysts for Suzuki and Heck coupling has been studied in an attempt to demonstrate the effect of side groups on catalytic activity. It was clearly seen that the location of side ? CH₃ groups which bound to benzene ring had little effect on catalytic activity. Interestingly when we changed these ? CH₃ groups with ? Cl groups the activity of the complexes increased. On the other hand, side groups which bound to imine nitrogen also had a large effect on catalytic activity. Copyright © 2008 John Wiley & Sons, Ltd.     

New route to synthesis of PVP‐stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross‐coupling reactions

Herein we report a new method for the synthesis and characterization of PVP‐stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP‐stabilized palladium(0) nanoclusters with a particle size of 4.5 ± 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 °C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV–vis, and XRD techniques. The PVP‐stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP‐stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and characterization of tris{2-(N,N-bis(diphenylphosphino) aminoethyl} amine derivatives: Application of a palladium(II) complex as a pre-catalyst in the Heck and Suzuki cross-coupling reactions

The polydendate bis(phosphino)amine, tris{2-(N,N-bis(diphenylphosphino)aminoethyl}amine 1 has been prepared in a single step from the reaction of tris(2-aminoethyl)amine with six equivalents of PPh₂Cl in the presence of NEt₃ in THF. Oxidation of 1 with aqueous H₂O₂, elemental sulfur or grey selenium gave the corresponding oxide, sulfide or selenide derivatives. [{(P(E)Ph₂)₂NCH₂CH₂}₃N] (E: 2a O, 2b S, 2c Se), respectively. Reaction of [{(PPh₂)₂NCH₂CH₂}₃N] with 3 equiv. of PdCl₂(cod) or PtCl₂(cod) gave the corresponding chelate complexes, [Pd₃Cl₆1] or [Pt₃Cl₆1]. The new compounds were fully characterized by NMR, IR spectroscopy and elemental analysis. The catalytic activity of the Pd(II) complex was tested in the Suzuki coupling and Heck reactions. The Pd(II) complex catalyzed the Suzuki coupling and Heck reaction affording biphenyls and stilbenes, respectively, in high yields.     

Synthesis and X‐ray structural characterization of a bidendate phosphine (dppe) palladium(II) complex and its application in Stille and Suzuki cross‐coupling reactions

The synthesis, characterization, crystal structure and catalyst activity of the bidentate phosphine complex [1,2‐bis(diphenylphosphino)ethane]palladium(II) bromide, [PdBr₂(dppe)], are presented. Treatment of 1,2‐bis(diphenylphosphino)ethane with palladium(II) bromide under mild conditions resulted in the compound in high yield and purity. The characterization of the synthesized compound was performed using spectroscopic methods, such as Fourier transform infrared and NMR, CHN analysis and X‐ray crystallography. The structure of the compound was slightly distorted square planar. This compound was found to work as an efficient catalyst for both Stille and Suzuki cross‐coupling reactions of various aryl halides with triphenyltin chloride and/or phenylboronic acid. Also, the catalyst could be recovered and reused several times without significant loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of new (N‐diphenylphosphino)‐isopropylanilines and their complexes: crystal structure of (Ph2P S)NH?C6H4?4?CH(CH3)2 and catalytic activity of palladium(II) complexes in the Heck and Suzuki cross‐coupling reactions

Three new (N‐diphenylphosphino)‐isopropylanilines, having isopropyl substituent at the carbon 2‐ (1) 4‐ (2) or 2,6‐ (3) were prepared from the aminolysis of chlorodiphenylphosphine with 2‐isopropylaniline, 4‐isopropylaniline or 2,6‐diisopropylaniline, respectively, under anaerobic conditions. Oxidation of 1,2 and 3 with aqueous hydrogen peroxide, elemental sulfur or gray selenium gave the corresponding oxides, sulfides and selenides (Ph₂P?E)NH? C₆H₄? 2‐CH(CH₃)₂, (Ph₂P?E)NH? C₆H₄? 4‐CH(CH₃)₂ and (Ph₂P?E)NH? C₆H₄? 2,6‐{CH(CH₃)₂}₂, where E = O, S, or Se, respectively. The reaction of [M(cod)Cl₂] (M = Pd, Pt; cod = 1,5‐cyclooctadiene) with two equivalents of 1,2 or 3 yields the corresponding monodendate complexes [M((Ph₂P)NH? C₆H₄? 2‐CH(CH₃)₂)₂Cl₂], M = Pd 1d, M = Pt 1e, [M((Ph₂P)NH? C₆H₄? 4‐CH(CH₃)₂)₂Cl₂], M = Pd 2d, M = Pt 2e and [M((Ph₂P)NH? C₆H₄? 2,6‐(CH(CH₃)₂)₂)₂Cl₂], M = Pd 3d, M = Pt 3e, respectively. All the compounds were isolated as analytically pure substances and characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, representative solid‐state structure of [(Ph₂P?S)NH? C₆H₄? 4‐CH(CH₃)₂] (2b) was determined using single crystal X‐ray diffraction technique. The complexes 1d–3d were tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and microwave‐assisted catalytic activity of novel bis‐benzimidazole salts bearing furfuryl and thenyl moieties in Heck and Suzuki cross‐coupling reactions

A mixture of bis‐benzimidazole salts ( 1–7 ), Pd(OAc)₂ and K₂CO₃ in DMF ? H₂O catalyzes, in high yield, the Suzuki and Heck cross‐coupling reactions assisted by microwave irradiation in a short time. In particular, the yields of the Heck and Suzuki reactions with aryl bromides were found to be nearly quantative. The synthesized bis‐benzimidazole salts ( 1 – 7 ) were identified by ¹H? ¹³C NMR, IR spectroscopic methods and micro analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and catalytic properties of bis(imino)pyridine palladium(II) complexes as efficient catalysts for Suzuki cross‐coupling reaction in water

Air‐stable bis(imino)pyridine palladium(II) complexes were synthesized and complex 12 proved to be a highly efficient catalyst for the Suzuki cross‐coupling reaction between aryl bromides and arylboronic acids in air using water as solvent. The coupling reaction proceeded smoothly under mild conditions to provide biaryls in excellent yields and Pd black was not observed. The recycling of the catalysts was also investigated, for up to three cycles, and complex 12 still exhibited good activity. Copyright © 2009 John Wiley & Sons, Ltd.     

Application of N,N‐bis(diphenylphosphino)aniline palladium(II) complexes as pre‐catalysts in Heck coupling reactions

Palladium(II) complexes with N,N‐bis(diphenylphosphino)aniline ligands catalyse the Heck reaction between styrene and aryl bromides, affording stilbenes in good yield. The structures of two of the complexes used as pre‐catalysts have been determined by single‐crystal X‐ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd.     

Suzuki and Heck coupling reactions mediated by palladium complexes bearing trans-spanning diphosphines

Palladium complexes of three trans-spanning diphosphines are examined for effecting C-C coupling reactions. Ten aryl halides of varying electron density were screened in Suzuki coupling reactions with phenylboronic acid and in Heck reactions with styrene. The results are discussed in terms of the unique flexibility and shape of the meta-terphenyl backbone upon which the diphosphine ligand is built.     

Iminophosphine palladium(II) complexes: synthesis,characterization, and application in Heck cross‐coupling reaction of aryl bromides

Palladium(II) complexes containing phosphorus and nitrogen donor atoms (iminophosphine), dichlorido{N‐[2‐(diphenylphosphino)benzylidene]‐2‐trifluoromethylaniline}palladium(II) 1 , dichlorido{N‐[2‐(diphenylphosphino)benzylidene]‐3‐trifluoromethylaniline}palladium(II) 2 , dichlorido{N‐[2‐(diphenylphosphino)benzylidene]‐2‐methylaniline}palladium(II) 3 , dichlorido{N‐[2‐(diphenylphosphino)benzylidene]‐3‐methylaniline}palladium(II) 4 have been successfully synthesized and fully characterized by FT‐IR and NMR (¹H, ³¹P, ¹⁹F, and ¹³C) spectroscopy techniques. These complexes were first step tested in the reaction of bromobenzene and styrene to determine the optimal coupling reaction conditions and then successfully applied as catalysts for Heck cross‐coupling reactions of activated and deactivated aryl bromides with styrene derivatives and several acrylates. Copyright © 2014 John Wiley & Sons, Ltd.     

Efficient and ligand free palladium catalyst for Suzuki and Heck cross-coupling reactions

A simple and efficient system for Suzuki cross-coupling reactions was developed using a ligandless catalyst of Pd nanoclusters generated in situ from Pd(acac)₂. The cross-coupling reactions proceeded under mild reaction conditions with a high reaction rate (5 min) to give various biaryls in high yields. The system also exhibited catalytic potential for Heck reaction between aryl bromides and styrene.     

Silica‐supported 3‐4,5‐dihydroimidazol‐1‐yl‐propyltriethoxysilanedichloropalladium(II) complex: Heck and Suzuki cross‐coupling reactions

A novel mesoporous silica‐nanotube‐supported 3‐4,5‐dihydroimidazol‐1‐yl‐propyltriethoxysilanedichloropalladium(II) complex was prepared and characterized. 3‐4,5‐Dihydroimidazol‐1‐yl‐propyltriethoxysilanedichloropalladium(II) and mesoporous silica‐supported 3‐4,5‐dihydroimidazol‐1‐yl‐propyltriethoxysilanedichloropalladium(II) were tested for catalytic activity for Heck coupling reactions between styrene and several aryl halides and Suzuki coupling reactions between phenylboronic acid and several aryl halides. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of novel palladium N‐heterocyclic‐carbene complexes as catalysts for Heck and Suzuki cross‐coupling reactions

Novel palladium‐1,3‐dialkylperhydrobenzimidazolin‐2‐ylidene (2a–c) and palladium‐1,3‐dialkylimidazolin‐2‐ylidene complexes (4a,b) have been prepared and characterized by C, H, N analysis, ¹H‐NMR and ¹³C‐NMR. Styrene or phenylboronic acid reacts with aryl halide derivatives in the presence of catalytic amounts of the new palladium‐carbene complexes, PdCl₂(1,3‐dialkylperhydrobenzimidazolin‐2‐ylidene) or PdCl₂(1,3‐dialkylimidazolin‐2‐ylidene) to give the corresponding C? C coupling products in good yields. Copyright © 2006 John Wiley & Sons, Ltd.     

Cross‐coupling reactions in water using ionic liquid‐based palladium(II)–phosphinite complexes as outstanding catalysts

Two new phosphinite ligands based on ionic liquids [(Ph₂PO)C₇H₁₄N₂Cl]Cl ( 1 ) and [(Cy₂PO)C₇H₁₄N₂Cl]Cl ( 2 ) were synthesized by reaction of 1‐(3‐chloro‐2‐hydoxypropyl)‐3‐methylimidazolium chloride, [C₇H₁₅N₂OCl]Cl, with one equivalent of chlorodiphenylphosphine or chlorodicyclohexylphosphine, respectively, in anhydrous CH₂Cl₂ and under argon atmosphere. The reactions of 1 and 2 with MCl₂(cod) (M = Pd, Pt; cod = 1,5‐cyclooctadiene) yield complexes cis‐[M([(Ph₂PO)C₇H₁₄N₂Cl]Cl)₂Cl₂] and cis‐[M(Cy₂PO)C₇H₁₄N₂Cl]Cl)₂Cl₂], respectively. All complexes were isolated as analytically pure substances and characterized using multi‐nuclear NMR and infrared spectroscopies and elemental analysis. The catalytic activity of palladium complexes based on ionic liquid phosphinite ligands 1 and 2 was investigated in Suzuki cross‐coupling. They show outstanding catalytic activity in coupling of a series of aryl bromides or aryl iodides with phenylboronic acid under the optimized reaction conditions in water. The complexes provide turnover frequencies of 57 600 and 232 800 h^?1 in Suzuki coupling reactions of phenylboronic acid with p‐bromoacetophenone or p‐iodoacetophenone, respectively, which are the highest values ever reported among similar complexes for Suzuki coupling reactions in water as sole solvent in homogeneous catalysis. Furthermore, the palladium complexes were also found to be highly active catalysts in the Heck reaction affording trans‐stilbenes. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis,characterization and catalytic activity of new aminomethyldiphosphine–Pd(II) complexes for Suzuki cross‐coupling reaction

A new range of CF₃‐substituted aminomethyldiphosphine (P―C―N) ligands ((C₆H₅)₂PCH₂)₂NR (R = ―C₆H₄(2‐CF₃) ( 1 ), ―C₆H₄(3‐CF₃) ( 1b ) has been synthesized from 2‐(trifluoromethyl)aniline and 3‐(trifluoromethyl)aniline with diphenylphosphine. The aminomethyldiphosphine ligands were reacted with Pd(cod)Cl₂ to give corresponding metal complexes, PdLCl₂ ( 2a , 2b ). The aminomethyldiphosphine–palladium compounds were characterized by utilizing several methods including NMR (¹H, ¹³C, ³¹P) and elemental analysis. These compounds were used as catalysts in Suzuki cross‐coupling reaction of aryl chlorides and bromides. The effect of base was also investigated in this current project. CF₃‐substituted aminomethyldiphosphine–palladium complexes were found to be efficient catalysts in Suzuki cross‐coupling reaction of activated and deactivated aryl boronic acids. Copyright © 2013 John Wiley & Sons, Ltd.     

Silica‐supported terpyridine palladium(II) complex as an efficient and reusable catalyst for Heck and Suzuki cross‐coupling reactions

Silica‐supported terpyridine palladium(II) was prepared and used as an effective and recyclable catalyst in Mizoroki–Heck and Suzuki–Miyaura coupling reactions. The catalyst was very effective for the Mizoroki–Heck reaction of aryl halides with olefins and conversion was in most cases excellent. The catalyst showed good thermal stability (up to 230 °C) and could be recovered and reused for four reaction cycles. The Suzuki coupling of aryl iodides with aryl boronic acids in the presence of the catalyst was also investigated and the reaction proceeded with a short reaction time and excellent conversion. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation of a titania‐supported highly dispersed palladium nano‐catalyst and its application in Suzuki and Heck coupling reactions

In this work, palladium complexes nanoparticles in titania are prepared by a pH‐controlled adsorption and without pH‐controlled adsorption method. This method results in high‐dispersion palladium on the titania surface. We demonstrate the use of the titania‐supported palladium as an efficient catalyst for Suzuki and Heck reactions of a representative range of aryl bromides and chlorides. The reusability of catalyst was tested, and deactivation process of the catalyst was not observed after four recycles. The catalysts were characterized by FT‐IR, NMR, elemental analysis, field emission scanning electron microscopy, transmission electron microscopy and X‐ray diffraction. Copyright © 2013 John Wiley & Sons, Ltd.     

Selective hydrogenation and Suzuki cross‐coupling reactions of various organic substrates using a reusable polymer‐anchored palladium(II) Schiff base complex

A new polymer‐anchored Pd(II) Schiff base complex has been prepared and characterized using scanning electron microscopy, elemental analysis, atomic absorption spectroscopy, TGA and spectrometric methods such as diffuse reflectance spectra of solid and FT‐IR spectroscopy. This polymer‐anchored palladium catalyst shows excellent catalytic activity in the liquid‐phase hydrogenation reaction of styrene oxide to obtain selectively 2‐phenylethanol at normal pressure of hydrogen gas (1 atm.) at room temperature in DMF medium. We have also studied the liquid‐phase hydrogenation reaction of various organic substrates. The catalyst exhibits excellent catalytic activity for the Suzuki cross‐coupling of various substituted and non‐substituted aryl halides. The influences of various parameters were investigated to optimize reaction conditions. The reusability experiments show that the catalyst can be used five times without much loss in catalytic activity. Copyright © 2012 John Wiley & Sons, Ltd.