Carbonylative Sonogashira Coupling Research Articles

Low‐valent Tungsten Catalyzed Carbonylative Sonogashira Coupling Reactions of Aryl Iodides with Alkynes

AbstractA low‐valent tungsten catalyzed carbonylative Sonogashira coupling reactions has been established. The present protocol utilizes inexpensive and readily available W(CO)6 as precatalyst and proceeds in the presence of atmospheric CO, providing a practical method to a series of functionalized alkynones and indoxyls compounds under mild reaction conditions. Moreover, the simple reaction system, good functional group tolerance and broad substrate scope enable the application of this transformation in the synthesis of functionalized carbonyl‐containing molecules.

Synthesizing and post-synthetically modifying metal-organic frameworks (Co(BDC)-NH2) for carbonylative sonogashira coupling reaction

In this study, a new functionalized metal-organic framework (MOF) [Co(BDCNH2)@Schiff-Base-Pd(II)] catalyst was synthesized using the post-synthetic modification of the Co(BDCNH2). The target MOF complex was formed by adding palladium chloride while binding di(pyridin-2-yl)methanone via a basic Schiff base formation reaction. The synthesized functionalized MOF was utilized as a highly efficient multifunctional catalyst in the Sonogashira carbonylative coupling reaction. Various analytical techniques elucidated the catalyst, including N2 isotherms, XPS, EDX FT-IR, XRD, SEM, ICP-OES, and TG-DTA. Notably, the synthesized Nano catalyst is reusable up to seven times with no considerable catalytic efficiency loss, high product yields, ease of extraction, short reaction times, and a wide range of substrates make this procedure environmentally friendly.

A Pd-Sn heterobimetallic catalyst for carbonylative Suzuki, Sonogashira and aminocarbonylation reactions using chloroform as a CO surrogate.

Herein, we report a heterobimetallic Pd-Sn catalyst for the carbonylative Suzuki coupling, aminocarbonylation reaction, and carbonylative Sonogashira coupling of aryl halides with boronic acids, amines, and aromatic alkynes leading to a three-component coupling reaction using in situ generated carbon monoxide. Under the optimized reaction conditions, a variety of bisaryl ketones, amides, and aromatic ynones have been synthesized in moderate to good yields in a one-pot fashion. The reported catalyst has wide reaction scope with good functional group tolerance.

The Sonogashira Carbonylation Reaction between Aromatic Bromide and Alkyne with N‐Formylsaccharin as a CO Source

AbstractThe carbonylative Sonogashira coupling reaction of aromatic bromide with terminal alkynes has been developed with N‐formylsaccharin as a CO source. The reaction, which has certain advantages in cost and safety of raw materials, is carried out in a simple and safe one‐pot method. A variety of alkynones with good functional group compatibility can be obtained in medium to high yields.

One‐Pot Palladium‐Catalyzed Carbonylative Sonogashira Coupling using Carbon Dioxide as Carbonyl Source

AbstractCarbonylation coupling reaction has emerged as a powerful and versatile strategy for the construction of carbonyl‐containing compounds in modern synthetic chemistry over the past years. Carbon dioxide, a renewable one carbon molecule, has become one of the most attractive and promising alternative carbonyl sources due to its highly abundance, nontoxicity and stability in comparison with CO in recent years. However, in most cases, a two‐chamber technique was generally necessary to allow the CO‐producing and CO‐consuming processes to perform successfully because of the complexities and incompatibility of reaction conditions, when carbon dioxide was utilized as carbonyl source. Herein, a practical one‐pot protocol using carbon dioxide as the carbonyl source for the palladium‐catalyzed carbonylative Sonogashira coupling has been established, providing an expedient and practical route to a wide range of functionalized alkynones and indoxyls under mild reaction conditions. By finding a suitable catalytic system, the method allowed the CO‐generating and CO‐consuming processes to proceed in one pot, wherein carbon monoxide was generated in situ from the reduction of carbon dioxide in the absence of any fluoride reagents. Simple and safe operation, readily available substrates, good functional group tolerance and mild reaction conditions are the features of the method.

Robust alkyl‐bridged bis(N‐heterocyclic carbene)palladium(II) complexes anchored on Merrifield's resin as active catalysts for the selective synthesis of flavones and alkynones

Highly active and efficient propylene‐bridged bis(N‐heterocyclic carbene)palladium(II) complexes covalently anchored on Merrifield's resin were synthesized and characterized using various physical and spectroscopic techniques. The two anchored Pd(II) complexes consist of the system: Merrifield's resin‐linker‐bis(NHC)Pd(II), the linkers being benzyl and benzyl‐O‐(CH2)3 for (Pd‐NHC1@M) and (Pd‐NHC2@M), respectively. The short linker anchored bis‐benzimidazolium ligand precursor (PBBI‐1@M) was synthesized via direct carbon–nitrogen alkylation of a propylene‐bridged bis(benzimidazole) (PBBI‐1) by Merrifield's resin chlorobenzyl group. The longer linker anchored bis‐benzimidazolium ligand precursor (PBBI‐2@M) was obtained in a two‐step reaction involving first alkylation of (PBBI‐1) with 3‐chloro‐1‐propanol followed by a nucleophilic substitution at Merrifield's resin chlorobenzyl group. Both supported ligand precursors (PBBI‐1@M and PBBI‐2@M) reacted with palladium acetate to produce the two heterogeneous catalysts (Pd‐NHC1@M) and (Pd‐NHC2@M). 13C NMR palladation shift of the benzimidazole N–C–N (C2) carbon was found very similar in both the liquid NMR spectra of the homogeneous complexes and the CP/MASS spectra of the corresponding covalently anchored complexes. The catalytic activity, stability, and the recycling ability of the supported catalysts have been investigated in the carbonylative Sonogashira coupling reactions of aryl iodides with aryl alkynes and alkyl alkynes and also in the cyclocarbonylative Sonogashira coupling reactions of aryl iodides with aryl alkynes via one pot reactions. The longer linker catalyst Pd‐NHC2@M demonstrated excellent catalytic activity, stability, and very high recycling ability in the two carbonylative coupling reactions. These systems exhibit the hypothesized thermodynamic stability offered by the chelate effect in addition to the strong sigma donor ability of a bis(NHC) ligand system generating electron‐rich palladium centers that favor the oxidative addition step of the aryl halide.

The synthesis of β-enaminones using trialkylamines and a Pd/DNA catalyst

A new one-pot procedure leading to β-enaminones has been developed. The elaborated methodology involves the cascade sequencing of carbonylative Sonogashira coupling of aryl iodide with a terminal alkyne and the oxidative dealkylation of tertiary amines. The efficient syntheses of β-enaminones were performed with a Pd/DNA catalyst, with NEt3, NPr3 and NBu3 used as amine sources. The catalyst was successfully recovered and used in several subsequent tests with the same results. The reaction mechanism, summarizing the activity of immobilized Pd NPs (palladium nanoparticles), was proposed.

Nickel (II) dibenzotetramethyltetraaza[14]annulene supported on DFNS nanoparticles catalyst in carbonylative sonogashira coupling

In this study, the carbonylative sonogashira coupling reaction was performed in the presence of CO (2 MPa) and Nitmtaa@DFNS as NPs. Nickel(II)dibenzotetramethyltetraaza[14]annulene complex (Nitmtaa) prepared and immobilized on amino-fucntionnalized DFNS (N-DFNS) via NiN (NH2) bond to obtain a stable and reusable new nanocatalyst named as Nitmtaa@DFNS. Good to superb performance products were provided deploying Nitmtaa@DFNS nanocatalyst. In addition, the anatomy of Nitmtaa@DFNS has been distinguished by various methods, including XRD, VSM, FT-IR, SEM, EDX, TEM, and TGA. In addition, the hot filtration test provided complete insight into the heterogeneity of the catalyst. The reuse and recycling of the catalyst were repeatedly investigated for coupling reactions. In addition, the mechanism of the coupling reactions was thoroughly studied.

Carboxyboronate as a Versatile In Situ CO Surrogate in Palladium‐Catalyzed Carbonylative Transformations

AbstractThe application of carboxy‐MIDA‐boronate (MIDA=N‐methyliminodiacetic acid) as an in situ CO surrogate for various palladium‐catalyzed transformations is described. Carboxy‐MIDA‐boronate was previously shown to be a bench‐stable boron‐containing building block for the synthesis of borylated heterocycles. The present study demonstrates that, in addition to its utility as a precursor to heterocycle synthesis, carboxy‐MIDA‐boronate is an excellent in situ CO surrogate that is tolerant of reactive functionalities such as amines, alcohols, and carbon‐based nucleophiles. Its wide functional‐group compatibility is highlighted in the palladium‐catalyzed aminocarbonylation, alkoxycarbonylation, carbonylative Sonogashira coupling, and carbonylative Suzuki–Miyaura coupling of aryl halides. A variety of amides, esters, (hetero)aromatic ynones, and bis(hetero)aryl ketones were synthesized in good‐to‐excellent yields in a one‐pot fashion.

Soft Heteroleptic N-Heterocyclic Carbene Palladium(II) Species for Efficient Catalytic Routes to Alkynones via Carbonylative Sonogashira Coupling.

N,N′-Substituted di-isopropyl (NHC-1), benzyl-isopropyl (NHC-2), and adamantyl-isopropyl (NHC-3) benzimidazolium salts react with palladium(II) bromide in pyridine to afford the corresponding trans-dibromidopyridinepalladium(II) complexes Pd-C1, Pd-C2, and Pd-C3 in high yields. A distorted square planar geometry for Pd-C2 and Pd-C3 was confirmed by single-crystal X-ray diffraction. The palladium(II) complexes show a remarkably higher catalytic activity and selectivity, compared to the literature data, in carbonylative Sonogashira coupling reactions of aryl iodides and aryl diiodides with aryl alkynes, alkyl alkynes, and dialkynes. Excellent yields with as low as 0.03 mol % loading of the catalyst were obtained. In the series of benzimidazolium (NHC) precursors, the 1H NMR signals of the α hydrogen show a consistent probing of the N-substituent donor strength. The density functional theory (DFT) quantum mechanical descriptors of the frontier orbitals were calculated. A linear correlation of the calculated absolute softness of the complexes versus the calculated percent buried volume (%Vbur) of their corresponding ligands was obtained. The catalytic activity experimental data are consistent with the hard soft acid base (HSAB)-predicted high affinity of the softest Pd-C3 complex for soft substrates, such as aryl iodides.

Solvent switchable Pd/DNA catalyst in carbonylative Sonogashira coupling

Palladium catalysts immobilized on DNA (Pd/DNA) were applied for the first time in the carbonylative Sonogashira coupling, at 1 atm of CO. Different alkynones were obtained with a high yield in DMF. In the presence of water, the selectivity completely changed and diaryl alkynes, typical Sonogashira products, were selectively formed. In addition to Pd/DNA, soluble palladium species also participated in the catalytic process. The stability of the catalytic system increased after the addition of DNA excess.

Recyclable heterogeneous palladium-catalyzed carbonylative Sonogashira coupling under CO gas-free conditions

A convenient, efficient and practical heterogeneous palladium-catalyzed carbonylative Sonogashira coupling of aryl iodides with terminal alkynes under CO gas-free conditions has been developed by using an MCM-41-supported bidentate phosphine palladium acetate complex as catalyst. Here, formic acid was used as the CO source with dicyclohexylcarbodiimide (DCC) as the activator and a wide variety of alkynyl ketones were generated in moderate to high yields. This heterogeneous palladium catalyst can be easily recovered via a simple filtration process and recycled up to 8 times without apparent loss of activity.

MnCl2‐Mediated Carbonylative Sonogashira Coupling of Aryl Iodides and Aromatic Terminal Alkynes by Using CO

AbstractA new, simple, and efficient synthetic protocol has been developed for Carbonylative Sonogashira Coupling (CSC) with aryl iodides, aromatic terminal alkynes, and CO (2 atm) by using manganese chloride (MnCl2) as a catalyst. This method has shown a good‐to‐excellent yield of the desired products. Additionally, it was found to have ensured the synthesis of 2‐substituted flavones.

Synthesis of d-glyco-alkynone derivatives via carbonylative Sonogashira reaction.

A carbonylative Sonogashira coupling approach to the synthesis of glyco-alkynones is described. Eighteen examples were obtained in moderate do nearly quantitative yields under mild conditions employing Mo(CO)6 as a safe carbon monoxide source. Functionalization of the alkynyl moiety via cycloaddition with organic azides provided six examples of glyco-triazoles.

Synthesis of α,β-alkynyl ketones via the nickel catalysed carbonylative Sonogashira reaction using oxalic acid as a sustainable C1 source.

An efficient and economic nickel-dppb catalyzed, carbonylative Sonogashira cross-coupling reaction was demonstrated to provide rapid access to various α,β-alkynyl ketones from aryl iodides and terminal alkynes using oxalic acid as the ex situ C1 source in a double vial (DV) system. Notably, the role of the ligand in combination with the Ni catalyst for the selective formation of carbonylative Sonogashira products was investigated and supported with control experiments. Yet, no reports are available for carbonylative Sonogashira coupling by using a CO-surrogate under Ni-catalyzed conditions. In this process, for the first time, oxalic acid is used as an ex situ solid, bench stable, easy to handle and efficient CO surrogate in a DV-system for the carbonylative Sonogashira coupling reaction with vast substrate scope.

Synthesis of Benzannulated [6,6]-Spiroketals by a One-Pot Carbonylative Sonogashira Coupling/Double Annulation Reaction.

A one-pot Pd-catalyzed carbonylative Sonogashira coupling in tandem with double annulation reaction to synthesize benzannulated [6,6]-spiroketals from o-iodophenols and terminal alkynols or alkynyl phenols was achieved. The protocol provides straightforward and facile access to benzannulated [6,6]-spiroketals in moderate to good yields and excellent diastereoselectivities under balloon pressure of CO at room temperature.

Integration of CO2 Reduction with Subsequent Carbonylation: Towards Extending Chemical Utilization of CO2.

Currently, it still remains a challenge to amplify the spectrum of chemical fixation of CO2 , although enormous progress has been achieved in this field. In view of the widespread applications of CO in a myriad of industrial carbonylation processes, an alternative strategy is proposed in which CO2 reduction to CO is combined with carbonylation with CO generated ex situ, which affords efficiently pharmaceutically and agrochemically attractive molecules. As such, CO2 in this study was efficiently reduced by triphenysilane using CsF to CO in a sealed two-chamber reactor. Subsequently, palladium-catalyzed aminocarbonylation, carbonylative Sonogashira coupling of aryl iodides, and rhodium(I)-mediated Pauson-Khand-type reaction proceeded smoothly to yield amides, alkynones, and bicyclic cyclopentenones, respectively. Furthermore, the formed alkynones can further be successfully converted to a series of heterocycles, for example, pyrazoles, 3a-hydroxyisoxazolo[3,2-a]isoindol-8-(3aH)-one derivatives and pyrimidines in moderate yields. The striking features of this protocol include operational simplicity, high efficiency, and relatively broad application scope, which represents an alternative avenue for CO2 transformation.

Novel (N‐heterocyclic carbene)Pd(pyridine)Br2 complexes for carbonylative Sonogashira coupling reactions: Catalytic efficiency and scope for arylalkynes, alkylalkynes and dialkynes

New N,N′‐substituted imidazolium salts and their corresponding dibromidopyridine–palladium(II) complexes were successfully synthesized and characterized. Reactions of palladium bromide with the newly synthesized N,N′‐substituted imidazolium bromides (2a and 2b) in pyridine afforded the corresponding new N‐heterocyclic carbene pyridine palladium(II) complexes (3a and 3b) in high yields. Their single‐crystal X‐ray structures show a distorted square planar geometry with the carbene and pyridine ligands in trans position. Both complexes show a high catalytic activity in carbonylative Sonogashira coupling reactions of aryl iodides and aryl diiodides with arylalkynes, alkylalkynes and dialkynes.

Cyclization Reactions for the Synthesis of Phthalans and Isoindolines­

Oxygen and nitrogen heterocycles are present in a vast number of natural substrates and biologically active molecules. In particular, phthalan and isoindoline subunits are found in many classes of products such as antibiotics, antioxidants, antimycotics, pigments, and fluorophores. Therefore several procedures dedicated to the construction of these heterocycles have been developed. In this review, a detailed analysis of the literature data regarding the synthesis of these nuclei via cyclization reactions is reported.1 Introduction2 Phthalans2.1 Oxa-Pictet–Spengler Reaction2.2 Garratt–Braverman Cyclization2.3 Diels–Alder and Related Reactions2.4 [2+2+2] Cyclotrimerization of Alkynes2.5 Cycloetherification of ortho-Substituted Aromatics2.6 Tandem Carbonylative Sonogashira Coupling–Cyclization Reactions3 Isoindolines3.1 Amination of Dihalides3.2 Intramolecular Hydroamination3.3 Diels–Alder and Related Reactions3.4 [2+2+2] Cycloaddition Reactions3.5 Tandem Carbonylative Sonogashira Coupling–Cyclization Reactions4 Conclusions

Enhanced redox activity of a hollow conjugated microporous polymer through the generation of carbonyl groups by carbonylative Sonogashira coupling

The carbonylative Sonogashira coupling reaction enhanced the redox activity of a hollow conjugated microporous polymer.