Mechanisms for the oxidation of secondary alcohols by dioxoruthenium(VI) complexes

Wang, Zhao; Chandler, W. David; Lee, Donald G.

doi:10.1139/v98-087

Cited by 13 publications

(3 citation statements)

References 29 publications

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“…Only a singlestep, 2-e process will leave the ring intact while oxidizing the alcohol to the ketone. [28][29][30][31][32] We are not aware of any reports on the ring-opening kinetics, but the sequence of 1-e steps appears to have produced ring-opened products in every case without exception, [33][34][35] Scheme 2. On this basis we conclude that the Fe IV O 2+ /cyclobutanol reaction proceeds mostly (∼70%) by a 2-e path, as judged by cyclobutanone yield.…”

Section: Discussionmentioning

confidence: 99%

Reactivity of Aqueous Fe(IV) in Hydride and Hydrogen Atom Transfer Reactions

2004

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Oxidation of cyclobutanol by aqueous Fe(IV) generates cyclobutanone in approximately 70% yield. In addition to this two-electron process, a smaller fraction of the reaction takes place by a one-electron process, believed to yield ring-opened products. A series of aliphatic alcohols, aldehydes, and ethers also react in parallel hydrogen atom and hydride transfer reactions, but acetone and acetonitrile react by hydrogen atom transfer only. Precise rate constants for each pathway for a number of substrates were obtained from a combination of detailed kinetics and product studies and kinetic simulations. Solvent kinetic isotope effect for the self-decay of Fe(IV), kH2O/kD2O = 2.8, is consistent with hydrogen atom abstraction from water.

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Section: Discussionmentioning

confidence: 99%

Reactivity of Aqueous Fe(IV) in Hydride and Hydrogen Atom Transfer Reactions

2004

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“…(27), (28), (29), and (26) for benzyl alcohol, 4-nitrobenzyl alcohol, and 4-methoxybenzyl alcohol. The values for k 1 are within experimental error of each other as would be expected for this mechanism.…”

mentioning

confidence: 99%

Kinetic study of 2-propanol and benzyl alcohol oxidation by alkaline hexacyanoferrate(III) catalyzed by a terpyridyl ruthenium complex

Kelson

Phengsy

2000

Int. J. Chem. Kinet.

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“…The spectral data were comparable to those reported. 15 The ee was determined by HPLC analysis (Daicel chiralcel OB-H, hexane-i-PrOH). The absolute configuration was determined by comparison with the reported specific rotation.…”

Section: (R)-(4-fluorophenyl)(phenyl)methanol (4f)mentioning

confidence: 99%

Asymmetric Synthesis of Diarylmethanols: Development of a Hemilabile Phosphorus Ligand Based on the Concept of Conformational Control

Arao¹,

Suzuki²,

Kondo³

et al. 2006

Synthesis

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A s y m m e t r i c S y n t h e s i s o f D i a r y l m e t h a n o l s Abstract: The asymmetric synthesis of diarylmethanols using a new hemilabile phosphorus ligand based on the concept of conformational control is described.We have been interested in developing novel chiral ligands based on the concept of conformational control. 1 In order to expand the scope of our concept, we planned to develop novel hemilabile phosphorus ligand 2 1 with both soft and hard coordinated centers within one molecule. Figure 1 shows the possible design of a novel hemilabile ligand 1, such that the soft diarylphosphino group (PAr 2 ) coordinates with a soft metal and the hard diarylphosphoryl group (POAr 2 ) coordinates with a hard metal. These two types of coordination allow conformational fix of a soft metal-hard metal-hemilabile ligand 1 complex, leading to the creation of a favorable reaction environment. Figure 1 Possible design of a soft metal-hard metal-hemilabile ligand 1 complexThere are two typical approaches to the catalytic asymmetric synthesis of diarylmethanols, reduction of the corresponding diaryl ketones 3 or arylation of aromatic aldehydes. 4 However, efficient methods for the catalytic asymmetric synthesis of optically active diarylmethanols are limited. We were interested in applying the novel hemilabile ligand 1 to the rhodium-catalyzed asymmetric phenylation of aromatic aldehydes with phenylboronic acids as follows: (1) No successful examples for this rhodium-catalyzed asymmetric phenylation of aromatic aldehydes have been reported. 4a-d (2) Some successful methods 4e for the arylation of aromatic aldehydes make use of air-sensitive organozinc reagents, which limit large-scale application. A solution could be the application of arylboronic acids, which are easy to handle and are commercially available or are straightforward to prepare, to the preparation of chiral diarylmethanols. 4g Miyaura 4a has reported rhodium-2-(diphenylphosphino)-2¢-methoxy-1,1¢-binaphthyl 5 (Rh-MOP) catalyzed asymmetric phenylation of 1-naphthaldehyde (3a) with phenylboronic acid giving 1-naphthyl(phenyl)methanol (4a) with 41% ee. We first chose 2 as a substrate and began to screen a variety of 4,5-bis[(diarylphosphino)methyl]-1,3-dioxolane derivatives 2 as the precursor of hemilabile phosphorus ligand 1. 6 Since hemilabile phosphorus ligand 1 was found to be very easily oxidized to bis-phosphine oxide 5 in air, it was initially decided to produce 1 in situ with a rhodium(III) complex. The results are shown in Table 1. Reactions were carried out with 2.0 equivalents of sodium tert-butoxide as a base and phenylboronic acid in 1,2-dimethoxyethane-water (5:1) at 100°C. First, the effects of the pendant diarylphosphino (PAr 2 ) group were examined. As shown in Table 1, entries 1 and 2, the pendant diarylphosphino group plays an important role: compare Ar = Ph (58% yield, 2% ee) and Ar = 4-MeO-3,5-Me 2 C 6 H 2 7 (97% yield, 75% ee). In the case of entry 2, only a fragment of the monophosphine oxide sodium salt 6 was observed in the reactio...

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Mechanisms for the oxidation of secondary alcohols by dioxoruthenium(VI) complexes

Cited by 13 publications

References 29 publications

Reactivity of Aqueous Fe(IV) in Hydride and Hydrogen Atom Transfer Reactions

Reactivity of Aqueous Fe(IV) in Hydride and Hydrogen Atom Transfer Reactions

Kinetic study of 2-propanol and benzyl alcohol oxidation by alkaline hexacyanoferrate(III) catalyzed by a terpyridyl ruthenium complex

Asymmetric Synthesis of Diarylmethanols: Development of a Hemilabile Phosphorus Ligand Based on the Concept of Conformational Control

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