Rhodium-catalyzed hydroformylation reaction

Arylphosphines in rhodium catalyzed hydroformylation reactions exchange an aryl group for an alkyl, principally linear alkyl, corresponding to the alkene being hydro-formylated to give an alkyldiarylphosphine [22](see Equation 2.5). 

Fig. 6 Ligand-modified rhodium-catalyzed hydroformylation reaction cycle...

The procedure has been successfully tested on synthetic data and applied to the homogeneous rhodium catalyzed hydroformylation reaction, where the 2D tracks for the peak center positions of both organometallic intermediates and products were identified. If the data is collected in a very small region of composition... 

An example is the rhodium catalyzed hydroformylation reaction, which is an industrially important homogenous catalytic process [3]. In contrast, it is amazing that such an important transition-metal catalyzed C/C bond-forming process has been employed only rarely in organic synthesis [4]. Part of the reason stems from the difficulty in controlling stereoselectivity. Even though some recently developed chiral rhodium catalysts allow for enantio- and diastereoselective hydroformylation of certain specific classes of alkenes [5, 6], only little is known about the diastereoselective hydroformylation of acyclic olefins [7, 8]. 

The group of Van Leeuwen has reported the synthesis of a series of functionalized diphenylphosphines using carbosilane dendrimers as supports. These were applied as ligands for palladium-catalyzed allylic substitution and amination, as well as for rhodium-catalyzed hydroformylation reactions [20,21,44,45]. Carbosilane dendrimers containing two and three carbon atoms between the silicon branching points were used as models in order to investigate the effect of compactness and flexibility of the dendritic ligands on the catalytic performance of their metal complexes. Peripherally phosphine-functionalized carbosilane dendrimers (with both monodentate... 

The partial pressures of H2 and CO in two different catalytic runs of a rhodium-catalyzed hydroformylation reaction were 60 and 20 and 20 and 60 atm, respectively. What effects are expected on the rates ... 

Similar, but normally less effective and more complicated, chelation control of regio- and stereochemistry can be achieved in rhodium-catalyzed hydroformylation reactions of open chain alkenyl phosphites82 -84. 

The effect of phosphine and diphosphane ligands on the chemoselectivity and regioselectivity of the rhodium-catalyzed hydroformylation reaction of allylbenzenes... 

In the rhodium-catalyzed hydroformylation of 1-hexene, it has been demonstrated that there is a correlation between the solubility of 1-hexene in ionic liquids and reaction rates (Figure 5.3-4) [28]. 

Abstract Recent advances in synthetic aspects of the rhodium-catalyzed hydroformylation of alkenes are reviewed. Emphasis is given to practical improvements, efficient new catalysts for regioselective and enantioselective hydroformylation, and to applications of the reaction in organic synthesis. Furthermore, new developments in directed hydroformylation are covered as well as new approaches toward efficient hydroformylation catalysts employing the concept of self-assembly. 

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. 

The products of the rhodium-catalyzed hydroformylation were responsive to the reaction temperatures and, to a lesser degree, to the reaction pressure, as shown in Tables XXI-XXII. 

In the late 1960s, Wilkinson postulated the reaction cycle of the ligand-modified rhodium catalyzed hydroformylation (Fig. 6). 

The catalytic cycle for the rhodium catalyzed hydroformylation has been extensively studied mainly for RhH(CO)(PPh3)3. A general proposal [2,27] that includes the steps of the reaction is shown in Scheme 2. 

HRh(CO)2(diphosphite)] species are known to be the resting state in the hydroformylation reaction. See for instance van Leeuwen PWNM, Claver C (eds) (2000) Rhodium-Catalyzed Hydroformylation. Kluwer Academic Press, Dordrecht... 

For example, rhodium catalyzed hydroformylation of 2-formyl-N-allyl-pyrrol gives an approx. 1 1 mixture of iso- and u-aldehydes. The latter cyclizes immediately in an aldol reaction followed by dehydration giving 7-formyl-5,6-indolizine in up to 46% (Scheme 29) [83]. Since here only one of the aldehyde groups can act as the enolate nucleophile this cyclization proceed with high regioselectivity (Scheme 29). 

For the rhodium-catalyzed hydroformylation of propylene in an aqueous biphasic system. Cents et al. have shown that the accurate knowledge of the mass transfer parameters in the gas-liquid-liquid system is necessary to predict and optimize the production rate [180]. Choudhari et al. enhanced the reaction rate by a factor of 10-50 by using promoter Ugands for the hydroformylation of 1-octene in a biphasic aqueous system [175]. 

Triphenylphosphine-Functionalized Amphiphiles for Rhodium-Catalyzed Hydroformylation and Palladium-Catalyzed Heck Coupling Reaction... 

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