Sonogashira-type cross-coupling reactions catalyzed by copper complexes of pincer N-heterocyclic carbenes

Domyati, Doaa; Latifi, Reza; Tahsini, Laleh

doi:10.1016/j.jorganchem.2018.02.028

Cited by 41 publications

(23 citation statements)

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“…In another recent work, Tahsini and co‐workers investigated the catalytic activity of a series of copper bis‐carbene mononuclear complexes ( 5 , Figure ) in Sonogashira couplings. These complexes efficiently catalyze the coupling of aryl iodides with phenyl acetylene derivatives in the presence of oxygen, while the reaction proceeds through a radical mechanism …”

Section: Introductionmentioning

confidence: 99%

“…These complexes efficiently catalyze the coupling of aryl iodides with phenyl acetylene derivatives in the presence of oxygen, while the reaction proceeds through a radical mechanism. [20] Considering the lack of a detailed study on the catalytic activity of simple, in-situ-prepared NHC/Cu-based catalytic systems in the Sonogashira reaction, along with the wide availabil-ity, low-cost and biocompatibility of copper, we herein report the development of a sustainable, inexpensive, straightforward and user-friendly protocol for this highly useful transformation. This protocol can be easily followed in any synthetic laboratory and requires a very simple experimental setup, along with widely available, stable (pre)catalytic components.…”

Section: Introductionmentioning

confidence: 99%

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A Sustainable, User‐Friendly Protocol for the Pd‐Free Sonogashira Coupling Reaction

et al. 2018

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We herein present a new catalytic system for the palladium‐free Sonogashira coupling reaction. The catalytically active moiety is formed in situ, in a straightforward and user‐friendly manner, by combining a widely available low‐cost copper salt and an N‐heterocyclic carbene precursor. A series of N‐heterocyclic carbene ligand precursors with variable structural features, some of which are novel, were tested and the reaction conditions were optimized. Using the catalytic system with the optimum performance, the scopes of the alkyne and the aryl halide were probed. Aryl iodides readily react with terminal alkynes, providing the coupling products in high to excellent yields. The protocol is highly efficient with alkynes bearing either alkyl or aryl substituents, the latter having either electron‐donating or electron‐withdrawing groups.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Sustainable, User‐Friendly Protocol for the Pd‐Free Sonogashira Coupling Reaction

et al. 2018

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“…The assistant role of oxygen in Cu-NHC catalyzed Sonogashira reaction was previously shown by the greater yield of the product in air than that under argon (Domyati et al, 2018). This effect in Ullmann-type coupling was examined by conducting the model reaction under argon using the same optimized conditions found in air.…”

Section: Resultsmentioning

confidence: 90%

“…Recently, we have developed mononuclear pyridylmethyl-linked Cu(I)-bis(NHC) complexes with alkyl wingtips, Cu-I(R) C∧ N ∧ C , and examined their catalytic reactivity in an air-assisted cross-coupling of terminal alkynes and aryl iodides (Domyati et al, 2016, 2018). Our interest in Ullmann-type coupling was driven partly by a need to synthesize N-arylated imidazole derivatives for our pyridine-based bis(NHC) ligands with aryl wingtips.…”

Section: Introductionmentioning

confidence: 99%

C−X (X = N, O) Cross-Coupling Reactions Catalyzed by Copper-Pincer Bis(N-Heterocyclic Carbene) Complexes

et al. 2019

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Over the last two decades, N-heterocyclic carbene (NHC)–copper catalysts have received considerable attention in organic synthesis. Despite the popularity of copper complexes containing monodentate NHC ligands and recent development of poly(NHC) platforms, their application in C–C and C–heteroatom cross-coupling reactions has been limited. Recently, we reported an air-assisted Sonogashira-type cross-coupling catalyzed by well-defined cationic copper-pincer bis(NHC) complexes. Herein, we report the application of these complexes in Ullmann-type C–X (X = N, O) coupling of azoles and phenols with aryl halides in a relatively short reaction time. In contrast to other well-defined copper(I) catalysts that require an inert atmosphere for an efficient C–X coupling, the employed Cu(I)-pincer bis(NHC) complexes provide good to excellent yields in air. The air-assisted reactivity, unlike that in the Sonogashira reaction, is also affected by the base employed and the reaction time. With Cs2CO3 and K2CO3, the oxygen-generated catalyst is more reactive than the catalyst formed under argon in a short reaction time (12 h). However, the difference in reactivity is compromised after a 24 h reaction with K2CO3. The efficient pincer Cu-NHC/O2/Cs2CO3 system provides great to excellent cross-coupling yields for electronically diverse aryl iodides and imidazole derivatives. The catalyst scope is controlled by a balance between nucleophilicity, coordinating ability, and the steric hindrance of aryl halides and N-/O-nucleophiles.

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“…Thus, in this work our aim is to introduce such a homogeneous catalyst which has already been proved as an efficient catalyst for different fundamental reactions and accordingly we have chosen pincer complex as the catalyst for the above mentioned conversion processes. For the transformation of CO 2 to formic acid, dehydrogenation of methanol and methylamine, different types coupling reactions and in many other cases pincer complexes have shown excellent catalyzing properties. By analyzing the reaction mechanisms of the pincer catalyzed processes, it is noticed that by utilizing the bi‐functional character of the pincer complexes, the nucleophilic and electrophilic attacks occur in two different centers (bi‐centric mechanism).…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Understanding of Bi‐functional Behavior of PNP‐Pincer Complexes Towards the Conversion of CO into Methanol and CO₂: A DFT Approach

2019

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The conversion mechanisms of CO into methanol through hydrogenation and CO 2 through hydrolysis catalyzed by (PNP) RuH 2 CO (1) pincer complex have been explored employing density functional theory (DFT). For both the reactions, we have identified two pathways. In pathway-I, at first the CO takes part in the reaction by interacting with the Ru-center of pincer complex and after that the H 2 /H 2 O molecule participates in the reaction, whereas in pathway-II, the generation of hydrogenated/hydrolyzed pincer from initial pincer via the assistance of H 2 or H 2 O molecule occurs first, followed by the reaction with CO. In case of hydrogenation, for both the pathways, CO is first converted to HCHO through hydrogenation which further undergoes hydrogenation to form methanol. In pathway-I, the reaction of HCHO with H 2 in presence of dehydrogenated pincer leads to produce methanol, whereas for pathway-II the hydrogenated pincer formed at the beginning of this pathway carries out the aforementioned conversion. Further in presence of methanol, CO is catalytically converted to methyl formate. On the other hand, in case of hydrolysis, the conversion of CO to CO 2 can be achieved in two ways, where 2 nd step, i. e. formic acid to CO 2 via formate ion formation follows similar mechanism for both the pathways. Overall, from our study it is revealed that the Rupincer complex acts as a promising homogeneous catalyst for converting CO to various organic chemical commodities.

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Sonogashira-type cross-coupling reactions catalyzed by copper complexes of pincer N-heterocyclic carbenes

Cited by 41 publications

References 58 publications

A Sustainable, User‐Friendly Protocol for the Pd‐Free Sonogashira Coupling Reaction

A Sustainable, User‐Friendly Protocol for the Pd‐Free Sonogashira Coupling Reaction

C−X (X = N, O) Cross-Coupling Reactions Catalyzed by Copper-Pincer Bis(N-Heterocyclic Carbene) Complexes

Comprehensive Understanding of Bi‐functional Behavior of PNP‐Pincer Complexes Towards the Conversion of CO into Methanol and CO₂: A DFT Approach

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Sonogashira-type cross-coupling reactions catalyzed by copper complexes of pincer N-heterocyclic carbenes

Cited by 41 publications

References 58 publications

A Sustainable, User‐Friendly Protocol for the Pd‐Free Sonogashira Coupling Reaction

A Sustainable, User‐Friendly Protocol for the Pd‐Free Sonogashira Coupling Reaction

C−X (X = N, O) Cross-Coupling Reactions Catalyzed by Copper-Pincer Bis(N-Heterocyclic Carbene) Complexes

Comprehensive Understanding of Bi‐functional Behavior of PNP‐Pincer Complexes Towards the Conversion of CO into Methanol and CO2: A DFT Approach

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Comprehensive Understanding of Bi‐functional Behavior of PNP‐Pincer Complexes Towards the Conversion of CO into Methanol and CO₂: A DFT Approach