Cu(I)/Chiral Bisoxazoline-Catalyzed Enantioselective Sommelet–Hauser Rearrangement of Sulfonium Ylides

Li, Shu-Sen; Wang, Jianbo

doi:10.1021/acs.joc.0c01590

Cited by 25 publications

(11 citation statements)

References 46 publications

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“…74 Experimental groups have expressed the need for quantum chemical studies to corroborate conclusions arrived at by control experiments which support free-ylide mechanisms for onium ylide [2,3]-sigmatropic rearrangement and [1,2]-sigmatropic rearrangement reactions. [2][3][4]61,68,75 Whether recently described selenonium ylide analogues are Rh-bound or 'free' has yet to be explored as well. In previous work, we demonstrated DFT calculations that a free ylide pathway is energetically favored over a metal-bound ylide pathway in Rh(II)-promoted indole formation of vinyl/azidoarenes.…”

Section: Methodsmentioning

confidence: 99%

Metal Bound or Free Ylides as Reaction Intermediates in Metal-Catalyzed [2,3]-Sigmatropic Rearrangements? It Depends

Laconsay

Tantillo

2021

ACS Catal.

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Density functional theory calculations were applied to study four previously published metalcatalyzed [2,3]-rearrangements from onium ylide intermediates, in pursuit of generalizations about when, during these types of reactions, catalysts dissociate. Our results corroborate past studies where free ylide mechanisms were proposed to be operative. Calculations on case studies predict that the origin of metal-catalyst 'falling off' (dissociation) can be attributed primarily to the steric bulkiness of functional groups adjacent to the carbene carbon.

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Section: Methodsmentioning

confidence: 99%

Metal Bound or Free Ylides as Reaction Intermediates in Metal-Catalyzed [2,3]-Sigmatropic Rearrangements? It Depends

Laconsay

Tantillo

2021

ACS Catal.

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“…A similar water-assisted 1,3-proton transfer process was proposed for the chiral Cu(I)/bisoxazoline-mediated asymmetric Sommelet− Hauser rearrangement of α-diazoesters by Wang's group. 35 On the basis of these findings and the crystal structure of catalyst, the key steps and possible working modes were given to understand the reaction process and stereocontrol (Scheme 12). Taking the [2,3]-Stevens rearrangement as an example, to avoid the steric repulsion between two substitutions of the sulfur reagent and the amide moieties in the catalyst, the Rconfigurated sulfonium ylide A1 is generated preferentially.…”

Section: [23]-stevens Rearrangement and Sommelet−hauser Rearrangementmentioning

confidence: 99%

Asymmetric Catalytic Rearrangements with α-Diazocarbonyl Compounds

2022

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Conspectus α-Diazocarbonyl compounds serve as nucleophiles, dipoles, carbene precursors, and rare electrophiles, enabling a vast array of organic transformations under the influence of metal catalysts. Among them, rearrangement processes are attractive and provide straightforward and efficient accesses to one-carbon extension adducts or heteroatom-containing molecules. The reactions occur upon the release of dinitrogen after nucleophilic addition or before ylide formation. Although significant progress has been made for these two types of rearrangement reactions, the issue of enantiocontrol is challenging because the final optically enriched products are generated via multistep transformations and the inherent spacial arrangement of the intermediates has more or less influence on the regio- and enantioselectivity. In this Account, we collected several rearrangements of α-diazocarbonyl compounds, showcasing the efficient catalysts and tailored strategies for tackling enantioselective varieties of these two types of rearrangement reactions. Our research group initiated the catalytic asymmetric reactions of α-diazocarbonyl compounds during the development of chiral Feng N,N′-dioxide–metal complex catalysts and others. As a kind of useful chiral Lewis acid catalyst chiral N,N′-dioxide–metal complexes are favorable for the activation of various carbonyl compounds, accelerating the diastereo- and enantioselective nucleophilic addition of α-diazoesters and the sequential rearrangements in either an intermolecular or intramolecular manner. Aldehydes, acyclic and cyclic ketone derivatives, and α,β-unsaturated ketones could participate in efficient asymmetric homologation reactions, and an obvious ligand-acceleration effect is observed in these processes. For example, the Roskamp–Feng reaction of aldehydes gives optically active β-ketoesters through a H-shift, overwhelming the aryl group shift or oxygen attack. The shift preference and enantiocontrol in the homologation of acyclic and cyclic ketone derivatives could be under excellent control of the chiral catalysts. An unusual electrophilic α-amination of aryl/alkyl ketones and even a complicated homologation/dyotropic rearrangement/interconversion/[3 + 2] cycloaddition cascade used to construct dimeric polycyclic compounds were discovered as a result of the selection of chiral ligands and additives. On the basis of the understanding of the interaction of the functional group with N,N′-dioxide–metal complexes in catalysis and the key enantio-determining issues in ylide-based rearrangements, we designed new α-diazocarbonyl compounds by introducing a pyrazole-1-carboxyl group as the acceptor unit, which could benefit the formation of both carbenoid species and the chiral catalyst-bound ylides to deliver stereoselectivity. Taking advantage of Ni(II) or Co(II) complexes of Feng N,N′-dioxide ligands, we realized several kinds of enantioselective [2,3]-sigmatropic rearrangements, such as the Doyle–Kirmse reaction with allylic sulfides or selenides, [2,3]-Stevens rearrangement...

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“…Based on experiments ,, and previous reports, , four possible pathways can be proposed for the catalytic [2,3]-sigmatropic rearrangements (Scheme ). After the nucleophilic addition of the allylic iodide/sulfide to the copper(I)-carbene, Path-A experiences the electrophilic attack of metal-bound iodonium ylide; Path-B undergoes the electrophilic attack of free ylide; Path-C undertakes electrophilic attack after keto–enol tautomerism; and Path-D proceeds via sequential keto–enol tautomerism and electrophilic attack of free ylide.…”

Section: Introductionmentioning

confidence: 94%

Mechanistic Studies of Copper(I)-Catalyzed Stereoselective [2,3]-Sigmatropic Rearrangements of Diazoesters with Allylic Iodides/Sulfides

2020

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Density functional theory calculations have revealed the mechanism and origin of regio- and stereoselectivity in [2,3]-sigmatropic rearrangements of diazoesters with allylic iodides/sulfides via chiral bisoxazoline-Cu(I) catalysts. Initially, the two catalytic systems share a similar process involving the generation of Cu(I)-carbene and the ensuing nucleophilic attack by allylic iodide/sulfide. Then, the rearrangements bifurcate at the generated metal-bound ylide species. For the iodonium ylide system, it prefers to undergo a Cu(I)-assisted five-membered envelope transition state to give the [2,3]-rearrangement product. However, for the sulfonium ylide system, it favors to form a free ylide that further allows a five-membered electrophilic transition state to offer the [2,3]-rearrangement product. The metal-bound ylide mechanism is disfavored for this [2,3]-rearrangement of sulfur ylide due to the severe substrate–ligand steric repulsions during the isomerization. Meanwhile, the free sulfonium ylide can be regarded as a sulfonium ylene with a CS bond owing to the strong electronegativity of sulfur and is stable, which promotes this pathway. In contrast, the free iodonium ylide is more like a zwitterion with a carbanion and an iodine cation due to the low electronegativity of iodine and is unstable, which requires the copper(I) center to stabilize the rearrangement. The regioselectivity is derived from the electronic effect of phenyl on the charge distribution over the allyl moiety. The stereoselectivity is mainly controlled by substrate–ligand steric interactions, wherein the favored pathway tolerates less steric hindrance between the substitutes of carbene and allyl moieties and the bulky groups on bisoxazoline ligand.

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Cu(I)/Chiral Bisoxazoline-Catalyzed Enantioselective Sommelet–Hauser Rearrangement of Sulfonium Ylides

Cited by 25 publications

References 46 publications

Metal Bound or Free Ylides as Reaction Intermediates in Metal-Catalyzed [2,3]-Sigmatropic Rearrangements? It Depends

Metal Bound or Free Ylides as Reaction Intermediates in Metal-Catalyzed [2,3]-Sigmatropic Rearrangements? It Depends

Asymmetric Catalytic Rearrangements with α-Diazocarbonyl Compounds

Mechanistic Studies of Copper(I)-Catalyzed Stereoselective [2,3]-Sigmatropic Rearrangements of Diazoesters with Allylic Iodides/Sulfides

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