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Scope and mechanism of the intermolecular addition of aromatic aldehydes to olefins catalyzed by Rh(I) olefin complexes.
J Am Chem Soc. 2007 Feb 21; 129(7):2082-93.JA

Abstract

Rhodium (I) bis-olefin complexes Cp*Rh(VTMS)(2) and CpRh(VTMS)(2) (Cp* = C(5)Me(5), Cp = C(5)Me(4)CF(3), VTMS = vinyl trimethylsilane) were found to catalyze the addition of aromatic aldehydes to olefins to form ketones. Use of the more electron-deficient catalyst CpRh(VTMS)(2) results in faster reaction rates, better selectivity for linear ketone products from alpha-olefins, and broader reaction scope. NMR studies of the hydroacylation of vinyltrimethylsilane showed that the starting Rh(I) bis-olefin complexes and the corresponding Cp*/Rh(CH(2)CH(2)SiMe(3))(CO)(Ar) complexes were catalyst resting states, with an equilibrium established between them prior to turnover. Mechanistic studies suggested that CpRh(VTMS)(2) displayed a faster turnover frequency (relative to Cp*Rh(VTMS)(2)) because of an increase in the rate of reductive elimination, the turnover-limiting step, from the more electron-deficient metal center of CpRh(VTMS)(2). Reaction of Cp*/Rh(CH(2)CH(2)SiMe(3))(CO)(Ar) with PMe(3) yields acyl complexes Cp*/Rh[C(O)CH(2)CH(2)SiMe(3)](PMe(3))(Ar); measured first-order rates of reductive elimination of ketone from these Rh(III) complexes established that the Cp ligand accelerates this process relative to the Cp* ligand.

Authors+Show Affiliations

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

17263531

Citation

Roy, Amy H., et al. "Scope and Mechanism of the Intermolecular Addition of Aromatic Aldehydes to Olefins Catalyzed By Rh(I) Olefin Complexes." Journal of the American Chemical Society, vol. 129, no. 7, 2007, pp. 2082-93.
Roy AH, Lenges CP, Brookhart M. Scope and mechanism of the intermolecular addition of aromatic aldehydes to olefins catalyzed by Rh(I) olefin complexes. J Am Chem Soc. 2007;129(7):2082-93.
Roy, A. H., Lenges, C. P., & Brookhart, M. (2007). Scope and mechanism of the intermolecular addition of aromatic aldehydes to olefins catalyzed by Rh(I) olefin complexes. Journal of the American Chemical Society, 129(7), 2082-93.
Roy AH, Lenges CP, Brookhart M. Scope and Mechanism of the Intermolecular Addition of Aromatic Aldehydes to Olefins Catalyzed By Rh(I) Olefin Complexes. J Am Chem Soc. 2007 Feb 21;129(7):2082-93. PubMed PMID: 17263531.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Scope and mechanism of the intermolecular addition of aromatic aldehydes to olefins catalyzed by Rh(I) olefin complexes. AU - Roy,Amy H, AU - Lenges,Christian P, AU - Brookhart,Maurice, Y1 - 2007/01/31/ PY - 2007/2/1/pubmed PY - 2007/3/29/medline PY - 2007/2/1/entrez SP - 2082 EP - 93 JF - Journal of the American Chemical Society JO - J Am Chem Soc VL - 129 IS - 7 N2 - Rhodium (I) bis-olefin complexes Cp*Rh(VTMS)(2) and CpRh(VTMS)(2) (Cp* = C(5)Me(5), Cp = C(5)Me(4)CF(3), VTMS = vinyl trimethylsilane) were found to catalyze the addition of aromatic aldehydes to olefins to form ketones. Use of the more electron-deficient catalyst CpRh(VTMS)(2) results in faster reaction rates, better selectivity for linear ketone products from alpha-olefins, and broader reaction scope. NMR studies of the hydroacylation of vinyltrimethylsilane showed that the starting Rh(I) bis-olefin complexes and the corresponding Cp*/Rh(CH(2)CH(2)SiMe(3))(CO)(Ar) complexes were catalyst resting states, with an equilibrium established between them prior to turnover. Mechanistic studies suggested that CpRh(VTMS)(2) displayed a faster turnover frequency (relative to Cp*Rh(VTMS)(2)) because of an increase in the rate of reductive elimination, the turnover-limiting step, from the more electron-deficient metal center of CpRh(VTMS)(2). Reaction of Cp*/Rh(CH(2)CH(2)SiMe(3))(CO)(Ar) with PMe(3) yields acyl complexes Cp*/Rh[C(O)CH(2)CH(2)SiMe(3)](PMe(3))(Ar); measured first-order rates of reductive elimination of ketone from these Rh(III) complexes established that the Cp ligand accelerates this process relative to the Cp* ligand. SN - 0002-7863 UR - https://www.unboundmedicine.com/medline/citation/17263531/Scope_and_mechanism_of_the_intermolecular_addition_of_aromatic_aldehydes_to_olefins_catalyzed_by_Rh_I__olefin_complexes_ L2 - https://doi.org/10.1021/ja066509x DB - PRIME DP - Unbound Medicine ER -