Palladium‐Catalyzed Construction of Amidines from Arylboronic Acids under Oxidative Conditions

Zhu, Fengxiang; Li, Yahui; Wang, Zechao; Orru, Romano V. A.; Maes, Bert U. W.; Wu, Xiao‐Feng

doi:10.1002/chem.201601262

Cited by 22 publications

(3 citation statements)

References 29 publications

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“…For example, amide derivatives can undergo CX (Scheme A) or C–X bond activation (Scheme B) . Alternatively, organometallic reagents can react with carbodiimides to form amidines. , More recently, various palladium-based methods have been developed including two-component reactions, in which a C–X bond is activated to form an organopalladium intermediate that then undergoes a reaction with a cyanamide (Scheme C), , and three-component reactions. − …”

Section: Introductionmentioning

confidence: 99%

Synthesis of Amidines by Palladium-Mediated CO₂ Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

et al. 2018

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A palladium-mediated one-pot synthesis of amidines from aromatic carboxylic acids and carbodiimides (RNCNR) is reported as an isoelectronic adaption of CO 2 ExIn (ExIn = Extrusion−Insertion) reactions developed for the synthesis of thioamides from carboxylic acids and isothiocyanates (RNCS). Multistage mass spectrometry (MS n ) experiments for model systems established "proof of concept", demonstrating decarboxylation of [(L)Pd(O 2 CAr)] + (L = 1,10-phenanthroline or py), to give [(L)PdAr] + , followed by reaction with a carbodiimide, RNCNR, to yield [(L)Pd(NRC(NR)Ar)] + (R = isopropyl). DFT calculations predicted these reactions as highly exothermic and occurring via carbodiimide insertion into the Pd−Ph bond. 2,6-Dimethoxy and 2,4,6-trimethoxy substitution for the Pd−Ar moiety results in slower reactions with minor changes in mechanism. The individual reaction steps associated with the conversion of 2,6-dimethoxybenzoic acid and 2,4,6trimethoxybenzoic acid into amidines in solution was probed by 1 H NMR spectroscopy as was the use of stoichiometric amounts of PdX 2 salts (X = O 2 CCH 3 and O 2 CCF 3 ) and three different carbodiimides, RNCNR (R = i Pr, c Hex, and Ph). Use of palladium trifluoroacetate gives less of the undesired protodecarboxylation product formed by protonation of the Pd−Ar bond to release ArH. DFT studies for solution phase one-pot reactions provide support for the mechanism and explain competitive factors contributing to the desired insertion step or the alternative protonation step to release ArH. An understanding of mechanism obtained from the model studies encouraged development of a solution-phase one-pot synthesis of N,N′diisopropyl-2,6-dimethoxybenzamidine using stoichiometric amounts of palladium carboxylates. Reaction conditions, product isolation and characterization, yields, and the scope of the one-pot synthesis of N,N′-R 2 -2,6-dimethoxybenzamidine were established, in which borohydride is added in workup as a hydrogen source. Attempts to make the chemistry catalytic in palladium are described.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Amidines by Palladium-Mediated CO₂ Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

et al. 2018

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“…Recent studies in the field of isocyanide insertions are directed towards further development of these imidoylative Buchwald-Hartwig type cross-couplings. To facilitate this, over the past couple of years there have been multiple reports on the mechanistic aspects of these reactions, allowing chemists to easier predict catalytic behavior and develop more effective catalysts [40][41][42].…”

Section: Cross-couplings With Oxygen or Nitrogen Nucleophilesmentioning

confidence: 99%

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

et al. 2020

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Isocyanides have long been known as versatile chemical reagents in organic synthesis. Their ambivalent nature also allows them to function as a CO-substitute in palladium-catalyzed cross couplings. Over the past decades, isocyanides have emerged as practical and versatile C1 building blocks, whose inherent N-substitution allows for the rapid incorporation of nitrogeneous fragments in a wide variety of products. Recent developments in palladium catalyzed isocyanide insertion reactions have significantly expanded the scope and applicability of these imidoylative cross-couplings. This review highlights the advances made in this field over the past eight years.

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“…When it comes to carbon unit, it is often used to construct C–N bonds, C–O bonds, or C–C bonds under palladium-catalyzed conditions . With the deepening of the research on isonitrile, it has been found that the combination of phenylboronic acid and isonitrile can be used as a C–C coupling carrier to construct organic heterocycle molecules in the reaction, from the initial synthesis of simple amides, aryl hydrazine, benzoic acid, and benzophenone, to the synthesis of heterocycles. , The two-phase coupling of phenylboronic acid with isonitrile is commonly used as a benzoyl building block in organic reactions . This method is milder considering the conditions for the preparation of the acyl chloride.…”

Section: Introductionmentioning

confidence: 99%

One-Pot Synthesis of N-Imidoyl-(1H)-indoles via Palladium-Catalyzed Oxidative Insertion Domino Reaction with Isocyanide and Arylboronic Acid

et al. 2019

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Palladium‐Catalyzed Construction of Amidines from Arylboronic Acids under Oxidative Conditions

Cited by 22 publications

References 29 publications

Synthesis of Amidines by Palladium-Mediated CO₂ Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

Synthesis of Amidines by Palladium-Mediated CO₂ Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

One-Pot Synthesis of N-Imidoyl-(1H)-indoles via Palladium-Catalyzed Oxidative Insertion Domino Reaction with Isocyanide and Arylboronic Acid

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Palladium‐Catalyzed Construction of Amidines from Arylboronic Acids under Oxidative Conditions

Cited by 22 publications

References 29 publications

Synthesis of Amidines by Palladium-Mediated CO2 Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

Synthesis of Amidines by Palladium-Mediated CO2 Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

One-Pot Synthesis of N-Imidoyl-(1H)-indoles via Palladium-Catalyzed Oxidative Insertion Domino Reaction with Isocyanide and Arylboronic Acid

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Synthesis of Amidines by Palladium-Mediated CO₂ Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method

Synthesis of Amidines by Palladium-Mediated CO₂ Extrusion Followed by Insertion of Carbodiimides: Translating Mechanistic Studies to Develop a One-Pot Method