Itaconate, hydrogenation

In order to prove that the reaction was catalyzed heterogeneously and to exclude the possibility of leaching and homogeneous catalysis, hot filtration tests were performed [44]. For the dimethyl itaconate hydrogenation, removal of the COD-RhDuphos immobilized on Al-SBA-15 effectively stopped the reaction after 5 h. After 24 h, the conversion of the filtered sample remained at 40%, whereas the original batch with catalyst was converted completely (Fig. 2.1.6.4). 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

Although the asymmetric hydrogenation of itaconic acid derivatives is a potential synthetic approach to many useful product [105], lower enantioselectivities are often reported. In contrast with other catalysts, f-Bu-BisP, Ad-BisP, t-Bu-MiniPHOS, BIPNOR 27, and Brown s ligand 25 gave high to almost perfect ees in the hydrogenation of these substrates (Scheme 23) [101]. 

Scheme 23. Rh-catalyzed asymmetric hydrogenation reactions of itaconic acid derivatives...

Bidentate chiral bis(aminophosphanes) such as 55-57 (Scheme 44) have been used for the Rh(I)-cataIyzed asymmetric hydrogenation of itaconic acid... 

Reaction Characteristics of Immobilized Ru-BINAP Catalysts in Asymmetric Hydrogenation of Dimethyl itaconate... 

In this work, various Ru-BINAP catalysts immobilized on the phosphotungstic acid(PTA) modified alumina were prepared and the effects of the reaction variables (temperature, H2 pressure, solvent and content of triethylamine) on the catalytic performance of the prepared catalysts were investigated in the asymmetric hydrogenation of dimethyl itaconate (DMIT). 

Effect of reaction conditions on the asymmetric hydrogenation of dimethyl itaconate over immobilized Ru-BINAP catalyst... 

The formation of a stable hydrogen-bonded ring structure as in poly(itaconic acid) and in poly(maleic acid) has also been shown to affect hydration states (Muto, Komatsu Nakagawa, 1973 Muto, 1974). 

Poly(acrylic acid) is very soluble in water as are its copolymers with maleic and itaconic acids. Solutions of 50 % by mass are easily obtained. The isomer of PAA, poly(ethylene maleic acid), is not so soluble. However, solutions of PAA tend over a period of time to gel when their concentration in water approaches 50 % by mass (Crisp, Lewis Wilson, 1975) this is attributed to a slow increase in the number of intermolecular hydrogen bonds. Copolymers of acrylic acid and itaconic acid are more stable in solution and their use has been advocated by Crisp et al. (1975, 1980). 

Short residence time and high heat transfer capabilities are demanded for the transfer hydrogenation of dimethyl itaconate, as in general for comparable liquid/liquid reactions [117]. 

On the other hand, Bolm et al. have reported, more recently, the use of BINOL-derived A -phosphino sulfoximines as ligands in the rhodium-catalysed hydrogenation of dimethyl itaconate and a-acetamidoacrylates, achieving excellent enantioselectivities of up to 99% ee (Scheme 8.12). In the main... 

In addition, several S/S ligands were also investigated for the asymmetric hydrogenation of olefins. In 1977, James and McMillan reported the synthesis of various disulfoxide ligands, which were applied to the asymmetric ruthenium-catalysed hydrogenation of prochiral olefinic acid derivatives, such as itaconic acid. These ligands, depicted in Scheme 8.16, were active to provide... 

In 1998, Ruiz et al. reported the synthesis of new chiral dithioether ligands based on a pyrrolidine backbone from (+ )-L-tartaric acid. Their corresponding cationic iridium complexes were further evaluated as catalysts for the asymmetric hydrogenation of prochiral dehydroamino acid derivatives and itaconic acid, providing enantioselectivities of up to 68% ee, as shown in Scheme 8.18. 

Scheme 8.16 Hydrogenation of itaconic acid with disulfoxide ligands.

Enantioselectivities of up to 47% ee were reported by Ruiz et al. in 1997 for the asymmetric hydrogenation of various prochiral dehydroamino acid derivatives and itaconic acid by using iridium cationic complexes of the novel chiral... 

On the other hand, James reported, in 1976, the use of a chiral sulfoxide as a ligand of ruthenium for the asymmetric hydrogenation of itaconic acid, providing a low enantioselectivity of 12% ee (Scheme 8.23). ... 

The efficiency of the new ligands was examined in enantioselective hydrogenation of some prochiral substrates. Itaconic ester hydrogenation using in situ prepared Rh-complexes was the first test reaction chosen. The best results from... 

Table 24.1. Enantioselective hydrogenation of dimethyl itaconate using Rh(l)-complexes ...

The results clearly show that these novel ligands are able to form a suitable asymmetric enviromnent around the metal resulting in high asymmetric induction. Their catalytic potential has been demonstrated in the highly enantioselective Rh-catalyzed hydrogenation of itaconates and a-enamides and Ru-catalyzed hydrogenation of p-functionalized ketone. 

Togni and co-workers have used the convergent methodology to link phosphine-containing chiral ferrocene ligands on the cyclophosphazene core to obtain dendrimeric structures of the type 37 (Fig. 21) (201). The reaction with the cyclophosphazene end occurs by the replacement of the P-Cl bond and by the formation of the P-0 bond. The dendrimers contain twelve and sixteen ferrocene moieties respectively. The phosphine units present can coordinate to Rh(I) to afford metallic dendrimers, which have been shown to be excellent catalysts for the enantioselective hydrogenation of dimethyl itaconate. The product... 

The aqueous biphase hydrogenation of dimethyl itaconate is accomplished with an Ir-(7 )-(7 )-3-benzyl(/>-sulfonate)-2,4-bis(diphenylphosphino)pentane complex.605... 

A 1996 work deposited four different catalytic metals on a p-cyclodextrin— epichlorohydrin copolymer to prepare Pd(Pt, Rh, Ru)-P-cyclodextrin copolymer catalysts.8 These were used to catalyze the asymmetric hydrogenations of the C=C bonds of trans-2-methyl-2-pentenoic acid, and dimethyl itaconate. 

Prochiral organic acids were hydrogenated on clay-supported Rh-chiral phosphine complexes.205,206 Hectorite-supported chiral Rh(I)-phosphine complexes were used for the asymmetric hydrogenation of a,P-unsaturated carboxylic acids.207 It was found that the interaction between the a-ester group of itaconates and phenyl groups of phosphine can play an important role in the determination of the configuration of products. 

A set of core-functionalized dendrimers was synthesized by Van Leeuwen et al. and one compound was applied in continuous catalysis. [45] The dendritic dppf, Xantphos and triphenylphosphine derivatives (Figures 4.22, 4.30 and 4.31) were active in rhodium-catalyzed hydroformylation and hydrogenation reactions (performed batch-wise). Dendritic effects were observed which are discussed in paragraph 4.5. The dendritic rhodium-dppf complex was applied in a continuous hydrogenation reaction of dimethyl itaconate. 

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