Synthesis of chitosan derivatives supported palladium complexes and their catalytic behavior in the Heck reaction

Two kinds of chitosan derivatives, crosslinked chitosan and crosslinked chitosan condense with salilylaldehyde, supported palladium complexes (CL‐CTS‐Pd and CL‐S‐CTS‐Pd) were synthesized and characterized by X‐ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential thermal analysis (DTA), etc. These complexes are efficient catalysts for the Heck reaction under atmospheric conditions and can be easily recovered and reused. The detailed studies show that the catalyst CL‐S‐CTS‐Pd is much more efficient than CL‐CTS‐Pd under the same conditions. CL‐S‐CTS‐Pd keeps its catalytic activity in the Heck reaction of acrylic acid with iodobenzene even at a low temperature (60°C) or with tiny amounts of the catalyst (0.05 mol%Pd). Yields of making cinnamic acid were even as high as 75.3% in the Heck reaction of acrylic acid with iodobenzene using CL‐S‐CTS‐Pd that was recovered 10 times. Copyright © 2005 John Wiley & Sons, Ltd.     

Palladium complexes of phosphinamine ligands in the intramolecular asymmetric Heck reaction

The synthesis of two novel cyclisation substrates for the asymmetric intramolecular Heck reaction is reported. Their cyclisation, in addition to a known substrate for cis-decalin formation, were tested with palladium complexes of BINAP and heterobidentate oxazoline-containing ligands. In general BINAP provides a more active catalyst system for the range of substrates tested although excellent enantioselectivities of up to 85% were obtained with the P,N ligands studied. A trend was noted whereby the t-leucine-derived oxazoline ligands were more reactive and enantioselective than the valine-derived analogues. Similarly, the diphenylphosphinoferrocenyloxazoline ligands were more reactive and selective than the corresponding diphenylphosphinophenyloxazoline ligands.     

Pd(II) complexes of novel phosphine ligands: Synthesis,characterization, and catalytic activities on Heck reaction

Novel phosphine oxides, (((3-methylpyridin-2-yl)amino)methyl)diphenylphosphine oxide (1) and diphenyl((pyrazin-2-ylamino)methyl)phosphine oxide (2), were synthesized and characterized. Phosphines ligands (3 and 4) were obtained by the reduction of 1 and 2 with AlH₃, monitored by ³¹P NMR spectroscopy. Pd(II) complexes of 3 and 4 were synthesized and characterized (5 and 6). The catalytic activity of 5 and 6 was tested on the reaction of styrene with both activated and deactivated aryl bromides in air. The results of the catalytic experiments were discussed through DFT calculations.     

Heck reaction catalyzed by a recyclable palladium supported on shell powder

A novel palladium catalyst supported on shell powder has been prepared, and its application to the Heck reaction of aryl iodides with olefins has been reported. The results showed that the novel catalyst had extremely high activities for the reactions with the average yield over 90%. Also, this catalyst showed excellent stability in Heck reactions, being reused three times. The catalyst was characterized by X‐ray powder diffraction and field‐emission scanned electron microscopy images, and the energy dispersive X‐ray analyzer. Copyright © 2010 John Wiley & Sons, Ltd.     

Palladium N-methylimidazolium supported complexes as efficient catalysts for the Heck reaction

Different N-methylimidazolium supported ligands have been easily synthesized. The palladium complexes derived from those materials can be used for the catalysis of the Heck reaction giving excellent yields, selectivities and very good TON and TOF values. The supported Pd-pincer complexes show an increased stability, and provide a clear improvement in the recovery and reuse for the supported catalysts.     

Substituted (pyridinyl)benzoazole palladium complexes: Synthesis and application as Heck coupling catalysts

The synthesis of 2-(4-tert-butylpyridin-2-yl)-benzooxazole (L3), 2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L4) and 6-tert-Butyl-2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L5) by intramolecular cyclization under basic conditions is described. Reactions of 2-pyridin-2-yl-1H-benzoimidazole (L1), 2-pyridin-2-yl-benzothiazole (L2) and L3–L5 with either [Pd(NCMe)₂Cl₂] or [Pd(COD)MeCl] afforded the corresponding mononuclear palladium complexes [Pd(L1)MeCl] (1), [Pd(L2)MeCl] (2), [Pd(L3)Cl₂] (3), [Pd(L3)MeCl] (4), [Pd(L4)Cl₂] (5), [Pd(L4)MeCl] (6) and [Pd(L4)MeCl] (7) as confirmed by mass spectrometry and elemental analyses. The palladium complexes are efficient Heck coupling catalysts for the reaction of iodobenzene with butylacrylate under mild conditions. Benzothiazole and benzooxazole containing complexes show faster induction periods compared to the benzoimidazole analogues.     

Solid support synthesis of 14- and 17-membered macrocycles via the SNAr methodology

Efficient assembly of 14-membered macrocycles utilizing the S_NAr of fluorine in 3-fluoro-4-nitrobenzoic acid with the OH of 3-hydroxytyrosine on solid support is reported. The flexibility of this synthesis, as well as the excellent purity (>90%) of the final products are the distinctive characteristic of the resultant library.     

Polymer‐supported palladium complexes with C,N‐ligands as efficient recoverable catalysts for the Heck reaction

A series of new polymer‐supported palladium complexes with C,N‐ligands (1a–e and 2a–c) were easily synthesized. The synthesized catalysts could be applied as efficient heterogeneous catalysts for the Heck coupling reaction (turnover frequency up to 12 600 h^?1). Additionally, the catalysts could be recovered by a simple filtration progress and could be reused for at least five times with a slow progressive decrease in activity. Copyright © 2010 John Wiley & Sons, Ltd.     

含杂环二茂铁亚胺异环环钯化合物在Heck反应中的催化活性研究

含杂环二茂铁亚胺异环环钯化合物结构新颖、独特,其催化的Heck偶联反应具有底物范围广、反应条件温和、催化活性高且催化诱导期短等优点。芳基碘代物、芳基溴代物和芳基氯代物都可作为反应底物,其中化合物2应用于芳基溴代物和丙烯酸乙酯的反应得到了100%的收率。在反应中加入四丁基溴化铵,且提高反应温度到140℃,带有斥电子取代基的芳基溴代物、芳基氯代物仍能以较高的产率得到偶联产物。实验中利用薄层色谱监测反应。     

Synthesis of a new troponoid liquid crystalline library on solid support

Five types of troponoids including 40 molecules were prepared by means of palladium(0)-catalyzed carbonylation and successive acylation or benzoylation after immobilization of 2-methoxy-5-trifluoromethylsulfonyloxytropone on solid support. Four types of them showed mesophases. The final products have enough purity to detect their mesomorphic properties.     

曲克芦丁钯配合物的制备及其对Heck反应的催化性能

制备了曲克芦丁钯配合物,利用红外光谱和紫外光谱表征了配合物的结构;同时考察了其对溴苯和丙烯酸的Heck芳基化反应的催化性能.结果表明:在反应物的物质的量之比(溴苯与丙烯酸)为1:2、反应温度120℃、反应时间8 h、三正丁胺为碱、四丁基溴化铵为溶剂的条件下,曲克芦丁钯配合物对溴苯和丙烯酸的Heck芳基化反应有较好的催化...     

padc-pd催化剂的制备及对heck反应的催化性能

padc;钯;负载型催化剂;heck反应     

Orthopalladated triarylphosphite complexes as highly efficient catalysts in the Heck reaction

An orthopalladated complex of commercially available tris(2,4-di-tert-butylphenyl)phosphite proves to be an extremely active catalyst in the Heck arylation of alkenes, with turnover numbers of up to 5,750,000 (mol product.mol Pd⁻¹) and turnover frequencies of up to nearly 300,000 (mol product.mol Pd⁻¹.h⁻¹).     

Effect of N1-substituted pyrazolic hybrid ligands on palladium catalysts for the Heck reaction

In this paper we have explored the influence of several linkers present on the [PdCl₂(L)] complexes, where L is 3,5-dimethylpyrazolic hybrid ligand N1-substituted by polyether chains and/or phenyl groups. These complexes have been used as pre-catalysts in the Heck reaction between phenyl halides and tert-butyl acrylate. The corresponding complexes efficiently catalyze the Heck olefination and provide good yields under phosphine-free conditions, even for aryl chlorides. Different reaction conditions were investigated and it was found that the nature of the ligand has an important influence on the effectiveness of the catalytic system. Ligand 1,8-bis(3,5-dimethyl-1H-pyrazol-1-yl)-3,6-dioxaoctane (L1), which has previously shown to be the most flexible and versatile, achieved high turnover numbers within very short reaction times and low catalyst loadings.     

淀粉负载钯催化剂的制备及对Heck反应的催化性能

淀粉负载钯催化剂的制备及对Heck反应的催化性能;淀粉;钯;负载型催化剂;Heck反应     

Asymmetric synthesis of the tricyclic core of cyathin diterpenoids via intramolecular Heck reaction

The enantioselective synthesis of the ketones 3 which displays the carbon core of NGF-inducing cyathane diterpenes is described. The key tricyclic trienone 22 was assembled in 13 steps from Michael adduct (R)-8a via intramolecular Heck cyclization of the chiral triflate 21. The trienone 22 was further elaborated into ketone 3 through trimethylaluminum-promoted expansion of the C-ring with trimethylsilyldiazomethane.