Iridium-Catalyzed Oxidative Dimerization of Primary Alcohols to Esters Using 2-Butanone as an Oxidant

Suzuki, Takayoshi; Matsuo, Tomohito; Watanabe, Kazuhiro; Katoh, Tadashi

doi:10.1055/s-2005-868492

Cited by 31 publications

(12 citation statements)

References 11 publications

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“…Previously, we reported that [Cp 2 ZrH 2 ] efficiently catalyzes the Tishchenko reaction of aldehydes to give esters through an alkoxyzirconium species, but not a hemiacetal. 90 3 and 4), and the reaction involving the addition of 2-anilinoethanol or 2-aminoethanol was 87 The above reaction employing 2-amino-2,2-diphenylethanol, prepared independently, and potassium carbonate as additives was found to give a comparable result to that using our system ( Table 3, entry 8). This result suggests that a similar iridium aminoalkoxide complex would be formed, even in our catalytic system.…”

Section: Scheme 25supporting

confidence: 68%

Iridium-Catalyzed Reactions Involving Transfer Hydrogenation, Addition, N-Heterocyclization, and Alkylation Using Alcohols and Diols as Key Substrates

Obora¹,

Ishii²

2010

Synlett

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This account gives an overview of iridium-catalyzed reactions developed by our group using mainly alcohols and diols as substrates. In the presented reactions, the iridium catalyst serves as a hydrogen acceptor from the alcohols giving iridium hydride, which is a key transient species. Herein, we report hydrogenation, alkylation, esterification, N-heterocyclization, and coupling reactions using alcohols and diols as reagents.

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Section: Scheme 25supporting

confidence: 68%

Iridium-Catalyzed Reactions Involving Transfer Hydrogenation, Addition, N-Heterocyclization, and Alkylation Using Alcohols and Diols as Key Substrates

Obora¹,

Ishii²

2010

Synlett

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“…The NBO charges on Ir do not change significantly on substitution of CO by PH 3 . The NBO charge on Ir that binds a PH 3 in Ir 2 PH 3 (CO) 7 is the same as that of Ir in Ir 2 (PH 3 ) 2 (CO) 6 , whereas that of the other Ir is the same as that of Ir in Ir 2 (CO) 8 . The Ir-Ir bond energy increases as PH 3 is substituted for CO.…”

Section: Resultsmentioning

confidence: 94%

“…Relative energies of the Ir 2 (PH 3 ) y (CO) z isomers are quite different between the coordinatively saturated clusters (Ir 2 PH 3 (CO) 7 and Ir 2 (PH 3 ) 2 (CO) 6 ) and the unsaturated clusters (Ir 2 (CO) 7 , Ir 2 PH 3 (CO) 6 , and Ir 2 (PH 3 ) 2 (CO) 5 ). Among the saturated clusters, the C 2v and C 2 isomers have similar relative energies (2d, 2e, and 2l, 2m, DE rel < 1.2 kcal/mol).…”

Section: Resultsmentioning

confidence: 97%

“…Iridium complexes play important roles in oxidation (e.g., of alcohols [4][5][6], phenols [7][8][9], and amines [10,11]), hydrogenation [12,13], C-H activation [14][15][16], cycloaddition (e.g., [2 + 2 + 2] [17][18][19], [2 + 2 + 1] [20,21], and [4 + 2] [22,23]), cycloisomerization [1,2], and ring-opening reactions [24]. The richness of this chemistry explains the broad interest in the properties of the family of iridium complexes and clusters [25].…”

Section: Introductionmentioning

confidence: 99%

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Structures, relative energies, and ligand dissociation energies of iridium carbonyl phosphine clusters

Zhang

Katz

Gates

et al. 2015

Computational and Theoretical Chemistry

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a b s t r a c tThere is significant interest in the catalytic properties of substituted iridium carbonyl clusters but little thermodynamic information available characterizing them. The low-energy isomers of Ir x (PH 3 ) y (CO) z (x = 1, 2, 4) were investigated with density functional theory and correlated molecular orbital theory at the coupled cluster CCSD(T) level. The relative energies and ligand dissociation energies were calculated. Differences in relative energies are consequences of both electronic and steric effects of the phosphines and carbonyls. The calculations predict three fundamental structural types for Ir 2 (PH 3 ) y (CO) z : C 2v , C 2 , and D 3d . Ten exchange-correlation functionals were used for the ligand dissociation energy calculations in addition to CCSD(T) for the smaller clusters. The xB97X-D functional gave the most consistent ligand dissociation energies as compared with the CCSD(T) benchmark calculations, and, so it was used to predict the dissociation energies for larger clusters when CCSD(T) calculations were infeasible. The dissociation energies characteristic of Ir 4 (PH 3 ) y (CO) z were in the range of $30 to $60 kcal/mol. Dissociation of a bridging ligand often involved a hydrogen atom transfer from a phosphine to a coordinatively unsaturated iridium atom and a phosphine converting from a bridging site to an equatorial site. The products of such reactions are predicted to have lower relative energies than other isomers.Phosphines act as r-electron donors, and there is a trend of an increase in carbonyl ligand dissociation energies as more phosphines are substituted in the small clusters.

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“…Complex 77 has also been reported to catalyze the oxidative dimerization of alcohols to esters when the reactions are performed in the presence of base [76]. The presence of base presumably encourages the reversible attack of the alcohol onto the initially formed aldehyde to give a hemiacetal, which is further oxidized to give the ester product.…”

Section: Asymmetric Transfer Hydrogenation Of Other Substratesmentioning

confidence: 98%

Iridium-Catalyzed Hydrogen Transfer Reactions

Saidi

Williams

2010

Iridium Catalysis

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This chapter describes the application of iridium complexes to catalytic hydrogen transfer reactions. Transfer hydrogenation reactions provide an alternative to direct hydrogenation for the reduction of a range of substrates. A hydrogen donor, typically an alcohol or formic acid, can be used as the source of hydrogen for the reduction of carbonyl compounds, imines, and alkenes. Heteroaromatic compounds and even carbon dioxide have also been reduced by transfer hydrogenation reactions. In the reverse process, the oxidation of alcohols to carbonyl compounds can be achieved by iridium-catalyzed hydrogen transfer reactions, where a ketone or alkene is used as a suitable hydrogen acceptor. The reversible nature of many hydrogen transfer processes has been exploited for the racemization of alcohols, where temporary removal of hydrogen generates an achiral ketone intermediate. In addition, there is a growing body of work where temporary removal of hydrogen provides an opportunity for using alcohols as alkylating agents. In this chemistry, an iridium catalyst "borrows" hydrogen from an alcohol to give an aldehyde or ketone intermediate, which can be transformed into either an imine or alkene under the reaction conditions. Return of the hydrogen from the catalyst provides methodology for the formation of amines or C-C bonds where the only by-product is typically water.

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Iridium-Catalyzed Oxidative Dimerization of Primary Alcohols to Esters Using 2-Butanone as an Oxidant

Cited by 31 publications

References 11 publications

Iridium-Catalyzed Reactions Involving Transfer Hydrogenation, Addition, N-Heterocyclization, and Alkylation Using Alcohols and Diols as Key Substrates

Iridium-Catalyzed Reactions Involving Transfer Hydrogenation, Addition, N-Heterocyclization, and Alkylation Using Alcohols and Diols as Key Substrates

Structures, relative energies, and ligand dissociation energies of iridium carbonyl phosphine clusters

Iridium-Catalyzed Hydrogen Transfer Reactions

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