Novel functionalised P-ligands: advances and application

Novel endo- and exocyclic phosphine ligands possessing different functionalities obtained by reduction of the PO precursors with desired stereochemistry are discussed. The diastereoselective deoxygenation including the catalytic reduction processes, the factors defining the reactivity and the role of the substituents on the stability of phosphorus atom configuration in a series of 3-aryl-3-phosphabicyclo[3.1.0]hexanes are reported. The complexation features of the ligands with Rh(III) and Pd(II) were examined and Rh(III) complexes were tested in styrene hydroformylation showing the structure-activity dependence.     

Syntheses of new polyamine dendrimer units via a tandem hydroformylation/reductive amination sequences

Rh-catalyzed tandem hydroformylation/reductive amination sequences (hydroaminomethylation) starting from olefins are applied to the synthesis of new polyamine dendrimer units using both convergent and divergent strategies in solution as well as on solid support.     

Phosphite Ligand Modified Supported Rhodium Catalyst for Hydroformylation of Internal Olefins to Linear Aldehydes

A phosphite ligand modified heterogeneous catalyst was developed for the hydroformylation of internal olefins to linear aldehydes, which showed a high activity and high regioselectivity and could be separated easily by filtration after reaction in an autoclave. Three nanoporous silica sieves were used to investigate the influence of pore structure and shape selective performance of support on the regioselectivity to the linear products.     

Rhodium-catalyzed hydroformylation of olefins: Effect of [bis(2,4-di-tert-butyl) pentaerythritol] diphosphite (alkanox P-24) on the regioselectivity of the reaction

Rhodium (I) associated with [bis(2,4-di-tert-butyl) pentaerythritol] diphosphite (I) as a ligand represents an active catalyst system for highly regioselective hydroformylation of various alkenes. The commercially available bis(2,4-di-tert-butyl)pentaerythritol diphosphite (alkanox P-24) (I), which has been used so far as an antioxidant in the stabilization of polymers, was used as a diphosphite ligand for the selective hydroformylation reaction of olefins. Excellent selectivity towards linear aldehydes and excellent conversions were achieved in the hydroformylation of alkenes. The hydroformylation reaction was applied to various olefinic substrates including the internal alkenes.     

Amine synthesis via carbonylation reactions: aminomethylation

The preparation of aliphatic amines and alicyclic diamines by reaction of olefins, synthesis gas and dimethylamine, known as aminomethylation, was investigated. Synthesis involves homogeneous rhodium and ruthenium catalysts or mixtures thereof at very low concentrations. Employing 3–12 ppm Rh and 50–100 ppm Ru results in up to 97% selectivity towards the amines at conversions of up to 98% if aliphatic mono-olefins are used as starting materials. At high catalyst concentrations (173 ppm Rh, 2660 ppm Ru) the corresponding diamine is obtained from dicyclopentadiene in 89% yield. The influence of reaction parameters and catalyst ratios on the n/i-selectivity of the product indicates the scope as well as the limits of such a multi-step synthesis for a commercial process.     

担载型水溶性膦铑配合物催化剂研究

烯类氢甲酰化反应包括了均相催化的某些重要应用。含贵金属和贵重配体的均相催化剂与产物的分离及制备高活性、高选择性、高稳定性催化剂,是均相催化及其多相化最活跃的研究领域之一。对于氢甲酰化催化剂多相化,在基础研究和技术上都仍存在如何解决好催化活性、反应选择性变化或金属流失等问题。将HRh(CO)[P(m-C_6H_4SO_33Na)_3]_3担载在亲水性     

PPh3衍生准多孔有机笼在Rh/PPh3体系催化氢甲酰化反应中的应用:增强活性和选择性及可回收利用

多孔有机笼(POCs)由英国利物浦大学的Cooper教授在2009年首次合成,这种多孔小分子材料的出现具有两方面重要意义:(1)开拓了多孔材料领域的一个全新分支,改变了人们对多孔材料的传统认知;(2)由于POCs材料由离散的小分子堆积而成,可溶解于一些常用的有机溶剂中,因此其在材料制备方面具有很好的"溶液成型"性能,该优势是三维延伸网状多孔材料所不具备的.POCs本质上是一种"中心带孔"的有机小分子,由刚性有机分子砌块收敛堆叠而成,其特殊结构在气体吸附与分离等方面表现出很好的应用前景.不同于传统空间延伸网状框架材料(如金属-有机框架材料和共价有机框架材料)及多孔有机聚合物(POPs)材料,POCs是一种在大多数有机溶剂中可溶解的小分子材料,因此在均相催化领域也有很好的应用前景.作为最为经典的有机配体,三苯基膦(PPh3)在金属有机化学和均相催化领域应用十分广泛,如目前均相催化工业应用最成功的典范之一氢甲酰化反应,大多数情况下使用的是PPh3与Rh形成的络合物催化剂.本文首先将PPh3进行醛基官能团化,通过醛基和氨基的收敛缩合形成POCs材料,合成了基于PPh3配体的准多孔有机笼(POC-DICP),利用得到的多孔有机笼制备出类Rh/PPh3均相催化体系的Rh/POC-DICP络合催化体系,并将其应用于氢甲酰化反应.相比于经典的Rh/PPh3均相催化体系,该Rh/POC-DICP催化体系在氢甲酰化反应中不仅展示出了更高的活性和目标产物醛的选择性(醛的化学选择性为97％,醛的正异构比为1.89),而且可以很方便地从均相反应体系中沉淀回收(通过调整溶剂体系极性).在氢甲酰化反应中,Rh/POC-DICP体系显示出了良好的底物适用性,在己烯、庚烯、辛烯和苯乙烯的氢甲酰化反应中均表现出良好的催化活性和醛选择性,同时催化剂回收使用4次,未见催化性能明显下降.X射线单晶衍射、同步辐射及DFT计算等结果表明,Rh/POC-DICP催化体系在氢甲酰化反应中具有较高活性和选择性的原因是POC-DICP多孔有机笼分子的有利的空间咬合角(123.88o)和P原子上相对的缺电子效应.本文设计合成的PPh3衍生的多孔有机笼不仅拓宽了多孔有机笼材料在催化领域的应用,而且为新型配体及络合催化剂的设计、合成及修饰提供了新的思路.     

Platinum complexes of malonate-derived monodentate phosphines and their application in the highly chemo- and regioselective hydroformylation of styrene

Neutral complexes of the formula PtCl₂L₂ (where L = diethyl 2-diphenylphosphino-malonate (1), diethyl 2-methyl-2-diphenylphosphinomalonate (2), dibenzyl 2-diphenylphosphinomalonate (3), 1,3-dihydroxy-2-methyl-2-diphenylphosphinopropane (4)) were prepared. These proved to be precursors to active catalysts for the hydroformylation of styrene. The platinum-containing catalytic systems prepared from ligand 4 provided the highest activity, while the platinum compounds prepared from other ligands all showed similar levels of reactivity to each other. The matching of high chemo- and regioselectivities were observed in most cases. Surprisingly, the complexes were practically inactive in imidazolium-type ionic liquids. ³¹P NMR studies on the PtCl₂L₂ complexes revealed that the stereoselectivity of the cis/trans geometrical isomers is strongly dependent on the structure of the ligand.     

Synthesis and characterisation of a new class of phosphine-phosphonite ferrocenediyl dinuclear rhodium complexes

We previously reported the easy access to mixed ferrocenediyl ligands bearing phosphine and phosphonite moieties. Using this strategy, a new enantiopure phosphine-menthylphosphonite ferrocenediyl has been synthesised. This mixed ligand leads to original unsymmetrical dinuclear rhodium coordination-complexes. One example of this new class of “quasi-close bridging A frame” dinuclear rhodium complexes, fully characterised by multinuclear ¹H, ¹³C, ³¹P and ¹⁰³Rh NMR and optical rotation measurements, is presented. Preliminary tests have shown an activity improvement in the hydroformylation of oct-1-ene using the phosphine-menthylphosphonite ferrocenediyl auxiliary compared to known phosphine-phosphonite ligands.     

Synthesis of new o-alkyl substituted arylalkylphosphanes: study of their molecular structure and influence on rhodium-catalyzed propene and 1-hexene hydroformylation

A set of new phosphane ligands designed to increase the branched-to-normal ratio of the hydroformylation reaction were prepared in the same way as the previously reported ortho-alkyl substituted arylphosphanes, which have shown increased i/n ratios in the hydroformylation of propene and 1-hexene. In order to determine the relationship between the catalytic behavior and stereoelectronic properties of the ligands, various functional alkyl groups (methyl, isopropyl, cyclohexyl) were placed on the phosphorus atom directly and in the ortho position of the phenyl ring connected to phosphorus. In the hydroformylation reaction of propene and 1-hexene a higher i/n ratio resulted with nearly all the ligands compared with that of triphenylphosphane. Additionally as the ortho-alkyl-substituent became larger, it had a favorable effect on the i-selectivity. Characterization of the ligands was carried out by NMR spectroscopy (mainly ¹H, ³¹P{¹H}, ¹³C{¹H}, HSQC/HETCOR and COSY-90). Properties of the ligands were also studied by quantum mechanical calculations and by synthesizing three Rh(acac)(CO)(PR₃) derivatives. The o-alkyl-substituent was orientated outside the ligands’ cone angle in the X-ray crystal structures of (2-cyclohexylphenyl)dicyclohexylphosphane and (2,5-dimethylphenyl)bis(4-pyridyl)phosphane, and Rh(acac)(CO)(PR₃) complex of (2-methylphenyl)dicyclohexylphosphane.