Evidence for a Ring-Opening Preequilibrium in the Exchange Reactions of Diosmacyclobutanes

Bender, Bruce R.; Ramage, David L.; Norton, Jack R.; Wiser, Dawn C.; Rappé, Anthony K.

doi:10.1021/ja963533+

Cited by 20 publications

(20 citation statements)

References 56 publications

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“…Furthermore, Corey and Noe proposed a (3 + 2) model for the origin of the high enantioselectivty of the dihydroxylation attained by an amine−OsO 4 complex . Although the [2 + 2] mechanism for the reaction of OsO 4 can also rationalize the stereoselectivities caused by chiral ligands, and the rearrangement of the metallaoxetane to a five-membered diolate was also supported by theoretical considerations, , many of recent theoretical and experimental studies that appeared during the course of this study support the (3 + 2) cycloaddition mechanism …”

Section: Introductionsupporting

confidence: 52%

Semiquantitative FMO Analysis of Substituent Effect on the Reaction of Permanganate Ion with Unsymmetrical Alkenes

et al. 1998

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The substituent effects on the reactions of permanganate ion with unsymmetrical alkenes are analyzed on the assumption of a concerted (3 + 2) cycloaddition model by using an equation obtained by approximation based on the FMO theory in which development and localization of the frontier molecular orbitals at the reaction sites with progress of the reaction are considered. The Hammett plots are successfully reproduced with the newly obtained rate data for the reactions of trans-chalcone and its derivatives and the data for methyl cinnamates, cinnamate ions, and alkyl vinyl ethers taken from the literature using FMO energies and orbital coefficients calculated by the PM3 method. It was indicated that a factor introduced to the basic equation in order to estimate the extent of localization of the molecular orbitals at the transition state is closely related to the position of the transition state along the reaction path.

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Section: Introductionsupporting

confidence: 52%

Semiquantitative FMO Analysis of Substituent Effect on the Reaction of Permanganate Ion with Unsymmetrical Alkenes

et al. 1998

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“…We then examined the trans-olefination. Norton et al previously revealed that the reversible trans-olefination of the diosmacyclobutane complex Os 2 (μ-η 1 :η 1 -C 2 H 4 )(CO) 8 proceeds in a stereoretentive manner 36 , 37 . Our group also reported that the trans-olefination of the μ-η 3 :η 3 -1,3,5-triene Pd 2 adduct with a linear 1,3,5-triene proceeds in a stereoretentive manner 25 .…”

Section: Resultsmentioning

confidence: 99%

Selective E to Z isomerization of 1,3-Dienes Enabled by A Dinuclear Mechanism

et al. 2021

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The E/Z stereocontrol in a C=C bond is a fundamental issue in olefin synthesis. Although the thermodynamically more stable E geometry is readily addressable by thermal Z to E geometric isomerization through equilibrium, it has remained difficult to undergo thermal geometric isomerization to the reverse E to Z direction in a selective manner, because it requires kinetic trapping of Z-isomer with injection of chemical energy. Here we report that a dinuclear PdI−PdI complex mediates selective isomerization of E-1,3-diene to its Z-isomer without photoirradiation, where kinetic trapping is achieved through rational sequences of dinuclear elementary steps. The chemical energy required for the E to Z isomerization can be injected from an organic conjugate reaction through sharing of common Pd species.

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“…Previous experimental work has suggested that such organometallic cycloaddition reactions are concerted and stereospecific, [21] and several theoretical studies support this postulate.…”

Section: (3)mentioning

confidence: 91%

“…Previous experimental work has suggested that such organometallic cycloaddition reactions are concerted and stereospecific, [21] and several theoretical studies support this postulate. [22] However, we see no economical way to explain our unusual observations by assuming that the imido ± allene cycloadditions are concerted processes.…”

Section: Zrmentioning

confidence: 96%

Synthesis of Chiral, Enantiopure Zirconocene Imido Complexes: Highly Selective Kinetic Resolution and Stereoinversion of Allenes, and Evidence for a Stepwise Cycloaddition/Retrocycloaddition Reaction Mechanism

Sweeney

Salsman

Andersen

et al. 2000

Angew. Chem. Int. Ed.

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Certain metal -carbon multiple bonds exhibit substantial reactivity toward organic compounds and are important intermediates in many catalytic processes. [1] The analogous reactivity of metal -heteroatom multiple bonds, such as those in metal -imido complexes, has been known for a much shorter time and has only relatively recently been utilized in synthetic applications.[2]We wish to report a series of highly enantioselective reactions using isolable imido complexes with reactive metal -nitrogen double bonds.[3-9] These involve the reactions of enantiopure (ebthi)(L)Zr=NR complexes with 1,3-disubstituted allenes (L = tetrahydrofuran; ebthi = bis (tetrahydroindenyl)ethane). Our observations a) demonstrate the operation of a general and highly selective kinetic resolution, b) provide the first example of a reaction that can be used to selectively invert the absolute configuration of one (symmetrically or unsymmetrically 1,3disubstituted) allene enantiomer within a racemic mixture, and c) provide strong mechanistic evidence for the stepwise nature of an organo-metallic cycloaddition reaction.Previous work in our laboratories has shown that zirconocene -imido complexes undergo cycloaddition reactions with a wide range of unsaturated organic molecules including alkynes, [10] imines,[11] and certain alkenes.[12] Several of these reactions are important steps in catalytic transformations (for example, hydroamination or imine metathesis) mediated by the imido compounds. To extend this chemistry to systems capable of enantioselective reactions, we decided to examine the reactions of chiral disubstituted allenes with zirconium imido complexes bearing the C 2 -symmetric ebthi ligand developed by Brintzinger.[13] The chiral imido complexes were synthesized in two steps from the known dimethyl complex 4, as shown in [Eq. ( 1)].[14] [**] This work was supported by the US National Institutes of Health (grant no. GM-25459 to R.G.B.). Z.K.S. acknowledges a fellowship from the Chevron Co. We are grateful to Dr. Jeffrey S. Johnson and Mr. Stephen R. Jenkins for experimental assistance and helpful discussions, Prof. David MacMillan and his co-workers for extensive assistance with chiral gas chromatography, and Boulder Scientific Co. for a gift of rac-(ebthi)ZrCl 2 .

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Evidence for a Ring-Opening Preequilibrium in the Exchange Reactions of Diosmacyclobutanes

Cited by 20 publications

References 56 publications

Semiquantitative FMO Analysis of Substituent Effect on the Reaction of Permanganate Ion with Unsymmetrical Alkenes

Semiquantitative FMO Analysis of Substituent Effect on the Reaction of Permanganate Ion with Unsymmetrical Alkenes

Selective E to Z isomerization of 1,3-Dienes Enabled by A Dinuclear Mechanism

Synthesis of Chiral, Enantiopure Zirconocene Imido Complexes: Highly Selective Kinetic Resolution and Stereoinversion of Allenes, and Evidence for a Stepwise Cycloaddition/Retrocycloaddition Reaction Mechanism

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