Computational study on alkenyl/aryl C(sp<sup>2</sup>)–O homolytic cleavage of carboxylates and carbamates

Zheng, Wenrui; Ding, Lanlan; Wang, Jiaoyang; Wang, Yingxing

doi:10.1039/c5ra27859g

Cited by 3 publications

(4 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Subsequently, activation of the aryl sulfamate occurs through a transition state containing a five-membered ring, in which an oxygen of the sulfonyl group is bound to nickel in addition to the Ni–aryl interaction. Similar pathways were proposed for related nickel systems. , The only work with palladium examined oxidative addition of phenyl sulfamate to (PCy 3 ) 2 Pd 0 and found that it had a prohibitively high barrier of 39.7 kcal/mol after dissociation of 1 equiv of the PCy 3 ligand, suggesting that catalysis would not occur with this particular system . This is consistent with our experimental results .…”

Section: Results and Discussionsupporting

confidence: 89%

“…Similar pathways were proposed for related nickel systems. 8f,20 The only work with palladium examined oxidative addition of phenyl sulfamate to (PCy 3 ) 2 Pd 0 and found that it had a prohibitively high barrier of 39.7 kcal/mol after dissociation of 1 equiv of the PCy 3 ligand, suggesting that catalysis would not occur with this particular system. 5 This is consistent with our experimental results.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst

et al. 2017

View full text Add to dashboard Cite

Aryl sulfamates are valuable electrophiles for cross-coupling reactions because they can easily be synthesized from phenols and can act as directing groups for C–H bond functionalization prior to cross-coupling. Recently, it was demonstrated that (1-tBu-Indenyl)Pd(XPhos)Cl (XPhos = 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl) is a highly active precatalyst for room-temperature Suzuki–Miyaura couplings of a variety of aryl sulfamates. Herein, we report an in-depth computational investigation into the mechanism of Suzuki–Miyaura reactions with aryl sulfamates using an XPhos-ligated palladium catalyst. Particular emphasis is placed on the turnover-limiting oxidative addition of the aryl sulfamate C–O bond, which has not been studied in detail previously. We show that bidentate coordination of the XPhos ligand via an additional interaction between the biaryl ring and palladium plays a key role in lowering the barrier to oxidative addition. This result is supported by NBO and NCI-Plot analysis on the transition states for oxidative addition. After oxidative addition, the catalytic cycle is completed by transmetalation and reductive elimination, which are both calculated to be facile processes. Our computational findings explain a number of experimental results, including why elevated temperatures are required for the coupling of phenyl sulfamates without electron-withdrawing groups and why aryl carbamate electrophiles are not reactive with this catalyst.

show abstract

Section: Results and Discussionsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Calculations on the alternative three-membered ring transition state suggested that this involves a higher energy barrier (Δ G ‡ > 29 kcal mol –1 ; see SI). The proposed pathway is consistent with others that have been calculated for related systems. , A similar pathway was also calculated for oxidative addition of phenyl sulfamate (phOSO 2 NMe 2 ; see Figure S25). Formation of the final dppf Ni II (nap)(sulf) product is exergonic by 16.2 kcal mol –1 .…”

Section: Resultssupporting

confidence: 89%

“…The proposed pathway is consistent with others that have been calculated for related systems. 10c,33 A similar pathway was also calculated for oxidative addition of phenyl sulfamate (phOSO 2 NMe 2 ; see Figure S25). Formation of the final dppf Ni II (nap)(sulf) product is exergonic by 16.2 kcal mol −1 .…”

Section: Resultsmentioning

confidence: 63%

Mechanistic Study of an Improved Ni Precatalyst for Suzuki–Miyaura Reactions of Aryl Sulfamates: Understanding the Role of Ni(I) Species

et al. 2017

View full text Add to dashboard Cite

Nickel precatalysts are potentially a more sustainable alternative to traditional palladium precatalysts for the Suzuki–Miyaura coupling reaction. Currently, there is significant interest in Suzuki–Miyaura coupling reactions involving readily accessible phenolic derivatives such as aryl sulfamates, as the sulfamate moiety can act as a directing group for the prefunctionalization of the aromatic backbone of the electrophile prior to cross-coupling. By evaluating complexes in the Ni(0), (I), and (II) oxidation states we report a precatalyst, (dppf)Ni(o-tolyl)(Cl) (dppf = 1,1′-bis(diphenylphosphino)-ferrocene), for Suzuki–Miyaura coupling reactions involving aryl sulfamates and boronic acids, which operates at a significantly lower catalyst loading and at milder reaction conditions than other reported systems. In some cases it can even function at room temperature. Mechanistic studies on precatalyst activation and the speciation of nickel during catalysis reveal that Ni(I) species are formed in the catalytic reaction via two different pathways: (i) the precatalyst (dppf)Ni(o-tolyl)(Cl) undergoes comproportionation with the active Ni(0) species; and (ii) the catalytic intermediate (dppf)Ni(Ar)(sulfamate) (Ar = aryl) undergoes comproportionation with the active Ni(0) species. In both cases the formation of Ni(I) is detrimental to catalysis, which is proposed to proceed via a Ni(0)/Ni(II) cycle. DFT calculations are used to support experimental observations and provide insight about the elementary steps involved in reactions directly on the catalytic cycle, as well as off-cycle processes. Our mechanistic investigation provides guidelines for designing even more active nickel catalysts.

show abstract

Theoretical study on the reaction mechanism of “ligandless” Ni-catalyzed hydrodesulfurization of aryl sulfide

et al. 2017

View full text Add to dashboard Cite

The reaction mechanism of Ni(COD) 2 catalyzed hydrodesulfurization of aryl sulfide PhSMe with HSiMe 3 as the reducing agent has been studied by using density functional theory methods. Both PhSMe-coordinated pathway and "ligandless" pathway have been identified and compared. It is found that these two reaction pathways are kinetically competitive and the s-complex assisted metathesis (s-CAM) transition state is the highest point on each energy profile for both pathways. Moreover, both the singlet and triplet reaction pathways of ligand substitutions have been compared and found that both singlet and triplet reaction mechanisms are competitive for the ligand substitution of COD with PhSMe on PhSMecoordinated pathway while the triplet mechanism holds a distinct advantage over singlet one for that of COD with HSiMe 3 on "ligandless" pathway.

show abstract

Computational study on alkenyl/aryl C(sp²)–O homolytic cleavage of carboxylates and carbamates

Abstract: The alkenyl/aryl C(sp2)–O cleavage and the substituent effect in both carboxylates/carbamates and corresponding Ni complexes were investigated in detail by wB97 method.

Cited by 3 publications

References 69 publications

DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst

DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst

Mechanistic Study of an Improved Ni Precatalyst for Suzuki–Miyaura Reactions of Aryl Sulfamates: Understanding the Role of Ni(I) Species

Theoretical study on the reaction mechanism of “ligandless” Ni-catalyzed hydrodesulfurization of aryl sulfide

Contact Info

Product

Resources

About

Computational study on alkenyl/aryl C(sp2)–O homolytic cleavage of carboxylates and carbamates

Abstract: The alkenyl/aryl C(sp2)–O cleavage and the substituent effect in both carboxylates/carbamates and corresponding Ni complexes were investigated in detail by wB97 method.

Cited by 3 publications

References 69 publications

DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst

DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst

Mechanistic Study of an Improved Ni Precatalyst for Suzuki–Miyaura Reactions of Aryl Sulfamates: Understanding the Role of Ni(I) Species

Theoretical study on the reaction mechanism of “ligandless” Ni-catalyzed hydrodesulfurization of aryl sulfide

Contact Info

Product

Resources

About

Computational study on alkenyl/aryl C(sp²)–O homolytic cleavage of carboxylates and carbamates