Synthesis of rhodium(I) complexes with the new dithiol chiral ligand (+)-trans-2,3-bis(mercaptomethyl)-bicyclo[2.2.2]octane (H2BCOS) their application as catalysts precursors in the styrene hydroformylation

The solution structures of the dominant species present during the styrene hydroformylation using rhodium precursors [Rh(µ-OMe)(cod)] 2 (1) and the dithiolate-bridged complex [Rh 2 (µ-BCOS)(cod) 2 ] 2 (9) in the presence of BDPP [(2S,4S)-bis(diphenylphosphine)pentane] have been determined. The high-pressure spectroscopic studies have revealed that the mononuclear complex [HRh(BDPP)(CO) 2 ] ( 7) is the predominant species during the hydroformylation process, but the dimeric species [Rh(BDPP)(CO) 2 ] 2 ( 8) is also present and in equilibrium with 7. Equilibrium constants were measured by 31 P NMR spectroscopy (at [Rh] ) 0.0138-0.0157 grat‚L -1 , 5-50 bar of H 2 , 5 bar of CO, 298-343 K, the molar ratio of 7:8 ranges from 1 to 20). Kinetic measurements have shown that the half-life of the species at ambient temperature is on the order of magnitude of 1 min. Variable-temperature 31 P and 1 H NMR spectra (293-193 K) revealed fluxional behavior in complex 7 where the bidentate diphosphine BDPP adopts equatorial-axial coordination to rhodium in the trigonalbipyramidal complex [HRh(BDPP)(CO) 2 ] (bite angle ≈90°). A low free energy of activation (∆G q 193K ) 44 kJ‚mol -1 and ∆G q 293K ) 44 kJ‚mol -1 ) for phosphorus exchange has been measured for the fluxional process observed in complex 7.

show abstract

“…Several studies related to asymmetric hydroformylation of olefins using dithiolate-bridged rhodium(I) complexes have been reported …”

Section: Introductionmentioning

confidence: 99%

Diphosphine and Dithiolate Rhodium Complexes: Characterization of the Species under Hydroformylation Conditions

Castellanos-Páez¹,

Castillón²,

Claver³

et al. 1998

Organometallics

101

View full text Add to dashboard Cite

show abstract

“…Substances 3c-e, 3i and 3k-l were synthesized using freshly prepared Grignard reagents in THF with an approximate concentration of 1 M. GC analysis of the product mixtures showed high selectivity in all cases (>96% de), favouring the desired products (endo-diols). Addition of the vinylic and aromatic Grignard reagents resulted in high yields (entries [6][7][8][9][10][11][12]. However, a large variation was observed with the alkyl Grignard reagents (entries [1][2][3][4][5].…”

Section: Resultsmentioning

confidence: 99%

“…[5][6][7][8][9][10] A number of Ti-diolates, and other complexes, useful as catalysts for the enantioselective reduction of ketones have been reported in the literature. [11][12][13][14][15][16] Most of these complexes were based on structures such as BINOLs 17 and TADDOLs, 18 which have often served as lead structures for the development of improved catalysts.…”

Section: Introductionmentioning

confidence: 99%

Bicyclo[2.2.2]octane-derived chiral ligands—synthesis and application of BODOLs in the asymmetric reduction of acetophenone with catecholborane

Friberg

Sarvary

Wendt

et al. 2008

Tetrahedron: Asymmetry

View full text Add to dashboard Cite

“…More cost-effective and safer large scale production of aldehydes for pharmaceutical use could provide great economic and health impacts. Asymmetric hydroformylation reactions can be used as a tool for the preparation of a large number of chiral products that can be used as precursors to organic compounds with therapeutic benefits (Castellanos-Paez, et al, 1997).…”

Section: Motivationmentioning

confidence: 99%

“…Asymmetric hydroformylation, however, provides an enantiomeric excess of one enantiomer relative to the production of the other enantiomer. Asymmetric hydroformylation has historically been done using transitionmetal complexes, primarily those using rhodium and platinum (Castellanos-Paez, et al, 1997). Additionally Wilkinson's catalyst was used for asymmetric hydrosilylation of ketones; since this catalyst provided asymmetric products, research grew in the area of using rhodium complexes with chiral phosphine ligands (Ojima, 2000).…”

Section: Asymmetric Hydroformylationmentioning

confidence: 99%

Asymmetric Hydroformylation of Styrene in Supercritical Carbon Dioxide

Kleman

2006

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Hydroformylation reactions in supercritical carbon dioxide can provide an environmentally conscious method of producing aldehydes for fine-chemical and pharmaceutical products. Asymmetric ligands, such as (R)-BINAP, can be used to provide an enantioselective product. When these reactions are performed in environmentally benign solvents, such as supercritical carbon dioxide (scCO2), additional environmental benefits are derived, such as ease of recycling of the solvent and unconverted reactants and elimination of the need for organic solvents. Rhodium-based catalysts have been prepared through the solid-phase reaction of catalyst precursors in supercritical carbon dioxide and evaluated for the hydroformylation of styrene to produce 2-phenylpropionaldehyde. Triphenylphosphine and (R)-BINAP were tested as ligands, and their effects on the reaction were examined. The catalyst, formed in situ in supercritical carbon dioxide (scCO2), was found to promote the hydroformylation of styrene with enantiomeric selectivity when (R)-BINAP ligands were used.

show abstract

Synthesis of rhodium(I) complexes with the new dithiol chiral ligand (+)-trans-2,3-bis(mercaptomethyl)-bicyclo[2.2.2]octane (H2BCOS) their application as catalysts precursors in the styrene hydroformylation

Cited by 22 publications

References 31 publications

Diphosphine and Dithiolate Rhodium Complexes: Characterization of the Species under Hydroformylation Conditions

Diphosphine and Dithiolate Rhodium Complexes: Characterization of the Species under Hydroformylation Conditions

Bicyclo[2.2.2]octane-derived chiral ligands—synthesis and application of BODOLs in the asymmetric reduction of acetophenone with catecholborane

Asymmetric Hydroformylation of Styrene in Supercritical Carbon Dioxide

Contact Info

Product

Resources

About