Hydroformylation Of Terminal Alkenes Research Articles

Ambient Pressure Hydroformylation – A Key Step to Meso‐Alkyl BODIPYs

AbstractHerein, a highly efficient five‐step reaction sequence to meso‐alkyl BODIPYs is presented. In our previous work, the hydroformylation of terminal alkenes was used to generate an aldehyde from an alkene via rhodium catalysis and use them in a subsequent tandem reaction to obtain BODIPY dyes. However, the use of higher pressures and therefore autoclaves as well as their necessary equipment might limit others to use this method. The refined approach in this work employs ambient pressure hydroformylation, done in a simple Schlenk tube and using a CO/H2 balloon, as key step towards an easier meso‐alkyl BODIPY synthesis. Additionally, the use of MTBE instead of chloroform as reaction solvent results in a greener approach. Readily available and easily synthesizable alkenes as well as different pyrrole building blocks can be used to extend the range of known alkyl‐BODIPYs. The synthesis of 23 derivatives with overall yields of up to 67 % demonstrates the wide applicability and advantages of the refined method.

Carbon Dioxide Transformation in Imidazolium Salts: Hydroaminomethylation Catalyzed by Ru-Complexes.

The catalytic species generated by dissolving Ru3 (CO)12 in the ionic liquids 1-n-butyl-3-methyl-imidazolium chloride or 1-n-butyl-2,3-dimethyl-imidazolium chloride are efficient multifunctional catalysts for: (a) reverse water-gas shift, (b) hydroformylation of alkenes, and (c) reductive amination of aldehydes. Thus the reaction of alkenes with primary or secondary amines (alkene/amine, 1:1) under CO2 /H2 (1:1) affords the hydroaminomethylations products in high alkene conversions (up to 99 %) and selectivities (up to 96 %). The reaction proceeds under relatively mild reaction conditions (120 °C, 60 bar=6 MPa) and affords selectively secondary and tertiary amines. The presence of amine strongly reduces the alkene hydrogenation competitive pathway usually observed in the hydroformylation of terminal alkenes by Ru complexes. The catalytic system is also highly active for the reductive amination of aldehydes and ketones yielding amines in high yields (>90 %).

Recent developments in cyclodextrin‐mediated aqueous biphasic hydroformylation and tsuji–trost reactions

New cyclodextrin‐based systems have recently been developed for aqueous organometallic catalysis. Through this review, the major advances made in the field are commented upon and discussed. The role of cyclodextrins as mass transfer promoters, molecular platforms, building blocks for the formation of Pickering emulsions and thermoresponsive catalytic systems is especially emphasized. The catalytic performances of these cyclodextrin‐based catalytic systems are highlighted in two model reactions, namely the rhodium‐catalysed hydroformylation of terminal olefins and the palladium‐catalysed cleavage of allyl carbonates (Tsuji–Trost reaction). Copyright © 2015 John Wiley & Sons, Ltd.

Realistic Energy Surfaces for Real‐World Systems: An IMOMO CCSD(T):DFT Scheme for Rhodium‐Catalyzed Hydroformylation with the 6‐DPPon Ligand

The hydroformylation of terminal alkenes is one of the most important homogeneously catalyzed processes in industry, and the atomistic understanding of this reaction has attracted enormous interest in the past. Herein, the whole catalytic cycle for rhodium-catalyzed hydroformylation with the 6-diphenylphosphinopyridine-(2H)-1-one (6-DPPon) ligand 1 was studied. This catalytic transformation is challenging to describe computationally, since two requirements must be met: 1) changes in the hydrogen-bond network must be modeled accurately and 2) bond-formation/bond-breaking processes in the coordination sphere of the rhodium center must be calculated accurately. Depending on the functionals used (BP86, B3LYP), the results were found to differ strongly. Therefore, the complete cycle was calculated by using highly accurate CCSD(T) computations for a PH3 model ligand. By applying an integrated molecular orbital plus molecular orbital (IMOMO) method consisting of CCSD(T) as high level and DFT as low-level method, excellent agreement between the two functionals was achieved. To further test the reliability of the calculations, the energetic-span model was used to compare experimentally derived and computed activation barriers. The accuracy of the new IMOMO method apparently makes it possible to predict the catalytic potential of real-world systems.

Water-soluble diphosphadiazacyclooctanes as ligands for aqueous organometallic catalysis

Abstract Two new water-soluble diphosphacyclooctanes been synthesized and characterized by NMR and surface tension measurements. Both phosphanes proved to coordinate rhodium in a very selective way as well-defined bidentates were obtained. When used in Rh-catalyzed hydroformylation of terminal alkenes, both ligands positively impacted the reaction chemoselectivity.

Formation of Acetals under Rhodium‐Catalyzed Hydroformylation Conditions in Alcohols

AbstractHydroformylation of terminal alkenes in alcohol solvents leads to the selective formation of the corresponding acetals. The Xantphos ligand gave the best results as well as acetal selectivities higher than 99% and linear/branched ratios of up to 52 were obtained. The scope of the reaction was studied. Acetals were found to be unreactive under hydroaminomethylation conditions.

Tandem Carbocupration/Oxygenation of Terminal Alkynes.

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Self-assembly of bidentate ligands for combinatorial homogeneous catalysis based on an A-T base pair model

Abstract A new concept for generation of chelating ligand libraries for homogeneous metal complex catalysis based on self-assembly is presented. Thus, self-assembly of structurally simple monodentate ligands in order to give structurally more complex bidentate ligands is achieved employing hydrogen bonding. Based on this concept and on the 2-pyridone/hydroxypyridine tautomeric system, a new rhodium catalyst was identified which operated with excellent activity and regioselectivity upon hydroformylation of terminal alkenes. In order to generate defined unsymmetrical heterodimeric ligands, an A-T base pair analog-the aminopyridine/isoquinolone system-was developed which allows for complementary hydrogen bonding. Based on this platform, a 4 x 4 phosphine ligand library was screened in the course of the rhodium-catalyzed hydroformylation of 1-octene. A catalyst operating with outstanding activity and regioselectivity in favor of the linear aldehyde was discovered.

ChemInform Abstract: Hydroformylation of Terminal Olefins in Water‐Organic Solvent Systems in the Presence of a Rhodium Complex Based on Functionalized Polyethyleneoxide.

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Chelation control in the hydroformylation of terminal alkenes

Hydroformylation of phosphine-bearing terminal alkenes can lead to a complete reversal of regioselection to that observed for simpler alkenes.