Minimizing the Amount of Nitromethane in Palladium-Catalyzed Cross-Coupling with Aryl Halides

Walvoord, Ryan R.; Kozlowski, Marisa C.

doi:10.1021/jo401249y

Cited by 38 publications

(9 citation statements)

References 34 publications

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“…Thus, the majority of arylation reactions (Scheme A) can be performed by combining appropriate bases (depending on the p K a of the substrate, amide and carbonate bases are normally used), BINAP or P( t -Bu) 3 as a ligand, and aprotic low-polarity solvents (THF, dioxane, and toluene are typical) . Reports by Vogl and Buchwald and Muratake and Nakai and our own studies summarize approaches for arylation of various nitro compounds, allowing a range of substituted structures to be accessed (Scheme B) . Interestingly, nitro compounds are completely unreactive under general arylation conditions.…”

Section: Introductionmentioning

confidence: 96%

Accounting for Strong Ligand Sensitivity in Pd-Catalyzed α-Arylation of Enolates from Ketones, Esters, and Nitroalkanes

Tcyrulnikov

Kozlowski

2020

J. Org. Chem.

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The mechanism of the Pd-catalyzed α-arylation of three model enolates is studied focusing on an analysis of their very different reactivities. In particular, the low reactivity of nitronates under standard arylation conditions and their high sensitivity to the nature of catalytic systems are addressed. The three canonical steps for each of the reaction systems are examined, and key trends surrounding the stability of intermediates and transition states are delineated. A framework based on molecular orbital analyses and the hard–soft acid–base (HSAB) theory is advanced to explain the observed reactivity trends. The local softness of the enolates was found to be a key parameter controlling the energy of the enolate–catalyst complexes. The low reactivity of the nitroalkane enolates is attributed to slow reductive elimination, a consequence of the hard nature of the nitronate. Analysis of reactivity of nitromethane in α-arylation with Pd catalysts containing Buchwald ligands reveals destabilization of the L2Pd species as a major non-enolate-specific acceleration mechanism as well as less electron-rich ligands accelerating reductive elimination as a nitronate-specific mechanism. The corresponding energetics and feasibility that favor C-arylation versus O-arylation are outlined.

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Section: Introductionmentioning

confidence: 96%

Accounting for Strong Ligand Sensitivity in Pd-Catalyzed α-Arylation of Enolates from Ketones, Esters, and Nitroalkanes

Tcyrulnikov

Kozlowski

2020

J. Org. Chem.

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“…16,17 While these advances in the field of oxidative coupling have facilitated the synthesis of a diverse array of ligands and natural products, they still require the use of high loadings of expensive transition metal catalysts, diamond electrodes, or stoichiometric oxidants that are not atom economical. 5,13,[18][19][20] In addition, many coupling patterns remain inaccessible, and couplings of mono-substituted phenols are especially challenging.…”

Section: Chart 1 Coupled Phenols Natural Productsmentioning

confidence: 99%

Oxidative Photocatalytic Homo- and Cross-Coupling of Phenols: Nonenzymatic, Catalytic Method for Coupling Tyrosine

2020

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The first, oxidative photocatalytic method for phenol-phenol homo-coupling and cross-coupling is described and isolated yields of up to 97% are obtained. Measured oxidation potentials and computed nucleophilicity parameters are consistent with a nucleophilic attack of one partner onto the oxidized radical form of the other partner. Understanding of this model permitted development of cross-coupling reactions between nucleophilic phenols/arenes and easily oxidized phenols in high selectivity and efficiency. A highlight of this method is that one equivalent of each coupling partner is utilized. Building on these findings, the first non-enzymatic, catalytic method for coupling tyrosine was developed. ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website. Experimental protocols and spectroscopic data (pdf).

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“…The nitro function appears as a promising alternative to amines. Indeed, nitro‐containing molecules are easily available by simple nitration with nitric acid, Henry reaction, palladium‐catalysed coupling of nitromethane or by functionalizing a nitro‐containing molecule using a hypervalent iodine reagent . The nitro function is mainly used as a precursor for the preparation of amines by reduction.…”

Section: Introductionmentioning

confidence: 99%

Straightforward and Sustainable Synthesis of Sulfonamides in Water under Mild Conditions

2018

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Ideally, a sustainable chemical synthesis should involve the use of non‐toxic solvents and reactants, easy separations and purification by energy‐efficient processes. In this context, reconsidering the synthesis of widely used drugs is especially timely and should allow important benefits to be obtained in terms of environmental impact. Sulfonamides are pertinent as their synthesis generally requires the use of toxic and/or hard‐to‐remove solvents such as dichloromethane, DMF and DMSO. In addition, toxic and highly reactive sulfur‐containing sources such as sulfonyl chloride are often involved and coupled with amines. Moreover, the latter may exhibit some toxicity and are generally difficult to purify. Herein, we disclose the unprecedented and sustainable synthesis of sulfonamides by using sodium sulfinate as a commercial and stable sulfur source and nitroarenes as the nitrogen‐containing reactant. In addition, under the optimized conditions only water is used as a “green” solvent and the products are collected by simple filtration.

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Minimizing the Amount of Nitromethane in Palladium-Catalyzed Cross-Coupling with Aryl Halides

Cited by 38 publications

References 34 publications

Accounting for Strong Ligand Sensitivity in Pd-Catalyzed α-Arylation of Enolates from Ketones, Esters, and Nitroalkanes

Accounting for Strong Ligand Sensitivity in Pd-Catalyzed α-Arylation of Enolates from Ketones, Esters, and Nitroalkanes

Oxidative Photocatalytic Homo- and Cross-Coupling of Phenols: Nonenzymatic, Catalytic Method for Coupling Tyrosine

Straightforward and Sustainable Synthesis of Sulfonamides in Water under Mild Conditions

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