Nickel-Catalyzed Desymmetrizing Cross-Electrophile Coupling of Cyclic <i>Meso</i>-Anhydrides

Lin, Tingzhi; Mi, Jianjun; Song, Lei; Gan, Jiamin; Luo, Pan; Mao, Jianyou; Walsh, Patrick J.

doi:10.1021/acs.orglett.8b00114

Cited by 34 publications

(9 citation statements)

References 84 publications

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“…It also provides evidence against the proposal that Mn or Zn are required for the activation of CO 2 and confirms that Ni I aryl species are highly nucleophilic. This suggests that they may also be able to insert other molecules with polar double bonds such as carbonyls, which could be relevant to cross-electrophile coupling reactions between aryl halides and aryl aldehydes or cyclic anhydrides …”

Section: Results and Discussionmentioning

confidence: 99%

“…The Ni I halide complex, (PPh 3 ) 3 Ni I Cl, is readily reduced by Mn 0 to regenerate the active Ni 0 species. We suggest that our revised mechanism is likely to be general to nickel-catalyzed reductive carboxylations of other organic halides and pseudohalides and possibly to the broader field of cross-electrophile coupling, where Lewis acids and halide sources are also commonly used. , Additionally, our revised mechanism provides guidance on how to improve reductive carboxylation reactions, a topic which is addressed in the following section.…”

Section: Results and Discussionmentioning

confidence: 99%

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Development of an Improved System for the Carboxylation of Aryl Halides through Mechanistic Studies

et al. 2019

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The nickel-catalyzed carboxylation of organic halides or pseudohalides using carbon dioxide is an emerging method to prepare synthetically valuable carboxylic acids. Here, we report a detailed mechanistic investigation of these reactions using the carboxylation of aryl halides with (PPh 3) 2 Ni II Cl 2 as a model reaction. Our studies allow us to understand several general features of nickel-catalyzed carboxylation reactions. For example, we demonstrate that both a Lewis acid and halide source are beneficial for catalysis. To this end, we establish that heterogeneous Mn(0) and Zn(0) reductants are multifaceted reagents that generate noninnocent Mn(II) or Zn(II) Lewis acids upon oxidation. In a key result, a rare example of a well-defined nickel(I) aryl complex is isolated, and it is demonstrated that its reaction with carbon dioxide results in the formation of a carboxylic acid in high yield (after workup). The carbon dioxide insertion product undergoes rapid decomposition, which ca These three oxidation states correspond to the onbe circumvented by a ligand metathesis reaction with a halide source. Our studies have led to both a revised mechanism and the development of a broadly applicable strategy to improve reductive carboxylation reactions. A critical component of this strategy is that we have replaced the heterogeneous Mn(0) reductant typically used in catalysis with a well-defined homogeneous organic reductant. Through its use, we have increased the range of ancillary ligands, additives, and substrates that are compatible with the reaction. This has enabled us to perform reductive carboxylations at low catalyst loadings. Additionally, we demonstrate that reductive carboxylations of organic (pseudo)halides can be achieved in high yields in more practically useful, non-amide solvents. Our results describe a mechanistically guided strategy to improve reductive carboxylations through the use of a homogeneous organic reductant, which may be broadly translatable to a wide range of crosselectrophile coupling reactions.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Development of an Improved System for the Carboxylation of Aryl Halides through Mechanistic Studies

et al. 2019

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“…More recently, a nickel-catalyzed asymmetric tandem alkylation/arylation of acrylates was developed by us . Like the reductive coupling of enolizable carbonyl compounds, the reductive coupling of homoenolates and their higher homologues (γ-metalated carbonyls) are underdeveloped …”

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confidence: 99%

“…We have been interested in reductive coupling of carbonyl-containing electrophiles, including asymmetric variants. ,, One of our goals is the use of α-functionalized electrophiles that undergo transposition of functionality to positions further removed from the carbonyl group. Recently, our team developed a nickel-catalyzed reductive coupling of nickel-bound homoenolates in which the homoenolates were catalytically generated via decarbonylation of cyclic anhydrides (Scheme a) .…”

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Nickel-Catalyzed Reductive Coupling of γ-Metalated Ketones with Unactivated Alkyl Bromides

et al. 2022

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A nickel-catalyzed reductive cross-coupling reaction of aryl cyclopropyl ketones with easily accessible unactivated alkyl bromides to access aryl alkyl ketones has been developed. This strategy facilitates access to various of γ-alkyl-substituted ketones via ring opening of cyclopropyl ketones (26 examples, 50–90% yield). Initial mechanistic studies revealed that the reaction proceeds via radical cleavage of the alkyl bromide.

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“…We have been interested in developing new transformations of homoenolates 45,46 and cross-electrophile coupling of cyclic anhydrides with aryl triflates to afford aryl ketoacids 47 . We were inspired by Yamamoto's stoichiometric reactions of nickel(0) complexes with anhydrides and Rovis's stoichiometric nickel promoted transformation with cyclic anhydrides and ZnPh 2 ( Fig.…”

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confidence: 99%

Nickel-catalyzed reductive coupling of homoenolates and their higher homologues with unactivated alkyl bromides

Lin

Qian

et al. 2020

Nat Commun

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The catalytic generation of homoenolates and their higher homologues has been a long-standing challenge. Like the generation of transition metal enolates, which have been used to great affect in synthesis and medicinal chemistries, homoenolates and their higher homologues have much potential, albeit largely unrealized. Herein, a nickel-catalyzed generation of homoenolates, and their higher homologues, via decarbonylation of readily available cyclic anhydrides has been developed. The utility of nickel-bound homoenolates and their higher homologues is demonstrated by cross-coupling with unactivated alkyl bromides, generating a diverse array of aliphatic acids. A broad range of functional groups is tolerated. Preliminary mechanistic studies demonstrate that: (1) oxidative addition of anhydrides by the catalyst is faster than oxidative addition of alkyl bromides; (2) nickel bound metallocycles are involved in this transformation and (3) the catalyst undergoes a single electron transfer (SET) process with the alkyl bromide.

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Nickel-Catalyzed Desymmetrizing Cross-Electrophile Coupling of Cyclic Meso-Anhydrides

Cited by 34 publications

References 84 publications

Development of an Improved System for the Carboxylation of Aryl Halides through Mechanistic Studies

Development of an Improved System for the Carboxylation of Aryl Halides through Mechanistic Studies

Nickel-Catalyzed Reductive Coupling of γ-Metalated Ketones with Unactivated Alkyl Bromides

Nickel-catalyzed reductive coupling of homoenolates and their higher homologues with unactivated alkyl bromides

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