Studies on transition-metal oxo- and nitrido-complexes. Part 3. Complexes of osmium tetraoxide with tertiary amines, and their reactions with alkenes

Cleare, M. J.; Hydes, P. C.; Griffith, William P.; Wright, Michael

doi:10.1039/dt9770000941

Cited by 31 publications

(15 citation statements)

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“…With the additional data provided by this study, we now favor the modified mechanism shown in Scheme I. The first step in this mechanism is the coordination of the olefinic bond to the metal center to give complex 5. With more basic ligands, such as pyridine2c and quinuclidine,5 isolable 1:1 adducts 6 are reversibly formed.…”

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confidence: 85%

Asymmetric induction in the reaction of osmium tetroxide with olefins

Hentges¹,

Sharpless²

1980

J. Am. Chem. Soc.

294

113

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Communications to the Editor 4263 carbomethoxy group. N M R examination of the crude reaction mixture did not reveal the presence of epimeric tricyclic ketal ester.I5 The formation of 18 implies that the reacting enolate derived from 17 is in the rotameric state shown in 17a. The reasons for this conformational specificity remain to be understood.Deprotection (p-TsOH, acetone) of 18 afforded the keto ester 19,7 mp 49-51 OC, which upon alkaline hydrolysis (aqueous KOH, dioxane, reflux 1 h) gave acid 20,' mp 132-135 OC, in 90% yield from 18. A variety of experiments probing the regiochemistry of a-substitution reactions about the ketone in compounds 19 and 20 indicated the exclusive formation of products derived from enol 21.I6-l8 Accordingly, keto acid 20 was subjected to selenenylationi8 (PhSeCI, ethyl acetate, room temperature 2.5 h). Oxidative treatment (CH2C12, H202, pyridine, room temperature) of the resultant a-phenylseleno ketone afforded the enone acid, 22,7 mp 142-146 OC, in 87% yield from 20. It was our intention to use the a,/3 unsaturation in 22 to force enolization in the required a' sense. Thus, enolization in the extended mode is prohibited by the bridgehead nature of the y carbon.

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confidence: 85%

Asymmetric induction in the reaction of osmium tetroxide with olefins

Hentges¹,

Sharpless²

1980

J. Am. Chem. Soc.

294

113

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“…It has long been recognized that the rate of reaction of OsO 4 with olefins is greatly increased in the presence of tertiary amines. Thus, OsO 4 reacts with monodentate tertiary amines under nonreducing conditions to give the adducts LOsO 4 (L = pyridine, , isoquinoline, phthalazine, ammonia, or dihydroquinidine derivatives , ).…”

Section: Introductionmentioning

confidence: 99%

Density Functional Study of the [2+2]- and [2+3]-Cycloaddition Mechanisms for the Osmium-Catalyzed Dihydroxylation of Olefins

et al. 1997

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The postulated intermediates in the base-free and base-assisted addition of OsO4 to olefins have been optimized using density functional theory (DFT). Ammonia was chosen as the base and ethylene as the olefin. The corresponding transition states have been characterized fully. Further, the activation barriers have been computed at the nonlocal level, and special attention has been given to the two different mechanistic hypothesis proposed for this reaction. In particular, the hypothesis by Sharpless of a [2+2]-cycloaddition pathway involving the formation of a four-member ring as an intermediate has been ruled out since the corresponding activation barrier was calculated to be as high as 39 kcal mol-1. The addition of a NH3 ligand to the osmium catalyst does not reduce significantly the [2+2] energy barrier. By contrast, it seems perfectly feasible that the dihydroxylation reaction proceeds through a [2+3] mechanism leading to the formation of a five-member ring intermediate as claimed by Corey. Such a process is found to be clearly exothermic and to involve a very small activation barrier of less than 2 kcal mol-1. A detailed analysis of the sequence describing exactly how the cycloaddition proceeds along the reaction path has also been performed by means of intrinsic reaction coordinate (IRC) calculations for the two studied mechanisms.

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“…[28] It is at 930 cm À1 for the hexamethylenetetramine•(OsO 4 ) 2 adduct in the solid and at 955 cm À1 in CCl 4 solution. [29] Cocrystals 2 a-f show this vibration at 900-910 cm À1 in the solid (consistent with non-minor vibrational changes of OsO 4 on adducts formation) and at higher frequencies (e.g., at 942 cm À1 for 2 a) in CHCl 3 solution, consistent with a partial dissociation of the adduct on dissolution. [30] Indeed, spectrophotometric studies showed that in solution the equilibrium between isolated OsO 4 and pyridine derivatives and the corresponding adducts is rapid even at low temperature [22] and equilibrium constants are extremely sensitive to steric effects.…”

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confidence: 52%

“…The ν3 vibration for pure OsO 4 is at 960 cm −1 in the gas phase and at 954 cm −1 in CCl 4 solution [28] . It is at 930 cm −1 for the hexamethylenetetramine ⋅ (OsO 4 ) 2 adduct in the solid and at 955 cm −1 in CCl 4 solution [29] . Cocrystals 2 a – f show this vibration at 900–910 cm −1 in the solid (consistent with non‐minor vibrational changes of OsO 4 on adducts formation) and at higher frequencies (e.g., at 942 cm −1 for 2 a ) in CHCl 3 solution, consistent with a partial dissociation of the adduct on dissolution [30] .…”

Section: Figurementioning

confidence: 97%

Molecular Electrostatic Potential and Noncovalent Interactions in Derivatives of Group 8 Elements

et al. 2021

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This communication reports experimental and theoretical evidences of σ‐hole interactions in adducts between nitrogen or oxygen nucleophiles and tetroxides of osmium or other group 8 elements. Cocrystals between pyridine or pyridine N‐oxide derivatives and osmium tetroxide are characterized through various techniques and rationalized as σ‐hole interactions using DFT calculations and several other computational tools. We propose the term “osme bond” (OmB, Om=Fe, Ru, Os, (Hs)) for naming the noncovalent interactions wherein group 8 elements have the role of the electrophile. The word osme is the transcription of ὀσμή, the ancient Greek word for smell that was used to name the heaviest group 8 element in relation to the smoky odor of its tetroxide.

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Studies on transition-metal oxo- and nitrido-complexes. Part 3. Complexes of osmium tetraoxide with tertiary amines, and their reactions with alkenes

Cited by 31 publications

References 0 publications

Asymmetric induction in the reaction of osmium tetroxide with olefins

Asymmetric induction in the reaction of osmium tetroxide with olefins

Density Functional Study of the [2+2]- and [2+3]-Cycloaddition Mechanisms for the Osmium-Catalyzed Dihydroxylation of Olefins

Molecular Electrostatic Potential and Noncovalent Interactions in Derivatives of Group 8 Elements

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