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Imidazo[1,2-a]pyridines and especially their amide derivatives exhibit a wide range of favourable pharmacological properties. In this work, Pd-catalysed carbonylation was used for the first time for the introduction of the carboxamide moiety into positions 6 or 8. A recyclable Pd catalyst, with palladium immobilised on a supported ionic liquid phase decorated with pyridinium ions, was used efficiently for the conversion of 6- or 8-iodo derivatives to the products. In the case of 6-iodo derivatives, a competing mono- and double carbonylation could be observed in the reactions of aliphatic amines as nucleophiles, but under the proper choice of reaction conditions, good-to-excellent selectivities could be achieved towards either the corresponding amides or α-ketomides. The heterogeneous catalyst showed excellent recyclability and low Pd-leaching. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis and application of a novel catalyst for carbon–carbon bond formations, comprising palladium immobilized on 2-(5-hydroxyquinolin-8-yl)-1H-benzo[d]imidazole-5-carboxylic acid modified superparamagnetic iron oxide nanoparticles (Pd@HQBI-SPION). The synthesis involved the attachment of HQBI ligands to SPION using APTES, followed by the immobilization of palladium. Characterization techniques, including FTIR, TEM, and magnetic measurements, confirmed the successful synthesis and structural integrity of Pd@HQBI-SPION. The catalytic activity of Pd@HQBI-SPION was evaluated in various carbon–carbon bond formation reactions, demonstrating high efficiency and reusability. 8 different derivatives bearing several electron withdrawing and electron donating functionalities were used as starting materials and the products were obtained in high isolated yields (75–97%). The catalyst exhibited excellent performance in one-pot synthesis of phenanthroline-dimedone polycyclic derivatives via C-alkylation followed by intramolecular O-alkylation of phenanthroline with dimedone. The products are obtained in high to excellent yields is described. This protocol presents a highly selective synthetic method for the construction of polycyclic aromatic compounds containing nitrogen and oxygen atoms. [ABSTRACT FROM AUTHOR]

Indole is a promising heteroarene in many natural products and pharmaceuticals; therefore, various synthetic methods for indole functionalizations have arisen in recent years. Herein, we report a Pd-catalyzed deoxygenative coupling for the N-vinylation of indoles by employing vinyl ethers. The vinylated indoles could be readily prepared in good to excellent yields with N1-regioselectivity regardless of the electronic characteristics and substitution patterns of indole substrates. Some indole-based pharmaceutical molecules, such as gramine, evodiamine, rutaecarpine, and melatonine, are also successfully vinylated. Moreover, carbazoles and indazoles are shown to participate. Additionally, vinylated indole can readily transform into structurally interesting indole derivatives. [ABSTRACT FROM AUTHOR]

The activation process is a key step in preparing porous carbon. Herein, three kinds of green activators were separately used to successfully prepare N-doped porous carbons through a two-step strategy: hydrothermal carbonization and chemical activation using microcrystalline cellulose as the carbon source and urea as the nitrogen source. Palladium was deposited on these N-doped microcrystalline cellulose-based carbons (NMC-X, where X represents the activator) via a traditional deposition–precipitation method, and the resulting Pd nanoparticle catalysts (Pd/NMC-X) showed high activity in the selective hydrogenation of quinoline under mild conditions, particularly Pd/NMC-ZC (ZC, zinc carbonate), which achieved complete conversion of quinoline within 100 min at 40 °C and 4 atm H2. Characterization results suggest that the high activity of Pd/NMC-ZC is mainly attributed to the special electronic structure of its Pd species, particularly the distribution of valence states and reducibility of Pd and the high hydrogen spillover capacity between Pd and NMC-ZC. The chemical activation by ZC leads to the formation of multiple defect sites on the carbon skeleton, modifying the carbon surface properties to enhance hydrogen spillover. This also provides an excellent environment for Pd nanoparticle anchoring, thus increasing the Pd-support interactions and regulating the electronic structure of Pd. [ABSTRACT FROM AUTHOR]

Chiral N‐heterocyclic compounds are key structures in natural compounds and pharmaceuticals, and they serve as essential building blocks of functional materials. Catalytic asymmetric cycloaddition reactions represent one of the most efficient synthetic strategies for constructing optically active heterocycles. Cyclic sulfamidate imines have recently come to be extensively studied and widely utilized in both organocatalytic and transition metal‐catalyzed asymmetric cycloadditions, where they have been shown to provide various N‐fused‐heterocycles and spiro‐cycles exhibiting high efficiencies with excellent stereoselectivities. This review highlights recent advancements in catalytic asymmetric cycloadditions of cyclic sulfamidate imines for the stereoselective synthesis of biologically active sulfamidate‐containing heterocycles since 2012 while focusing on the diverse reactivities of cyclic sulfamidate imines and the mechanisms of chiral induction in catalysis. [ABSTRACT FROM AUTHOR]

The effects of time, temperature and catalyst concentration were investigated for an optimised condition of biphenyl synthesis by Suzuki-Miyaura cross-coupling reactions by Neolyst catalysts. The optimisation process was analysed using Box Behnken Face-Centred Experimental Design in Response Surface Methodology (RSM). The design was employed to derive a statistical model for the effect of parameters studied on the yield of biphenyl. The coefficient of determination, r2 was 0.9883% after model reduction. With an optimum time of 6.63 h, a temperature of 73°C and with minimum catalyst concentration of 0.013 mol% gives the optimum conditions for the maximum yield of biphenyl. [ABSTRACT FROM AUTHOR]

The [PdCl2(Xantphos)] complex, in comparison with several [PdCl2(P–P)] complexes having different diphosphine chelating ligands (P–P), is very active as a catalyst for the carbonylation of iodobenzene to methyl benzoate. The run conditions and the influence of several cocatalysts have been also studied to further improve the catalytic activity. The optimization of the catalytic system allowed to obtain TOFs of ca. 260,000 h−1. The addition of some additives able to reduce the possible catalyst deactivation allowed to increase the TOF of ca. 15%. The best positive results were obtained by adding reducing agents such as ferrocene, which leads to a TOF higher than 300,000 h−1. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the synthesis and application of a novel catalyst for carbon–carbon bond formations, comprising palladium immobilized on 2-(5-hydroxyquinolin-8-yl)-1H-benzo[d]imidazole-5-carboxylic acid modified superparamagnetic iron oxide nanoparticles (Pd@HQBI-SPION). The synthesis involved the attachment of HQBI ligands to SPION using APTES, followed by the immobilization of palladium. Characterization techniques, including FTIR, TEM, and magnetic measurements, confirmed the successful synthesis and structural integrity of Pd@HQBI-SPION. The catalytic activity of Pd@HQBI-SPION was evaluated in various carbon–carbon bond formation reactions, demonstrating high efficiency and reusability. 8 different derivatives bearing several electron withdrawing and electron donating functionalities were used as starting materials and the products were obtained in high isolated yields (75–97%). The catalyst exhibited excellent performance in one-pot synthesis of phenanthroline-dimedone polycyclic derivatives via C-alkylation followed by intramolecular O-alkylation of phenanthroline with dimedone. The products are obtained in high to excellent yields is described. This protocol presents a highly selective synthetic method for the construction of polycyclic aromatic compounds containing nitrogen and oxygen atoms.

Objectives. To study the possibility of one-pot synthesis (combination of two processes in one reactor) for the following pairs of processes: (1) dehydration of 2-hexanol and isomerizing alkoxycarbonylation of the resulting 2-hexene, in order to obtain 2-hexyl heptanoate, and (2) dehydration of 2-hexanol and isomerizing methoxycarbonylation of the resulting 2-hexene, in order to obtain methyl esters of C7 carboxylic acids. To investigate the effect of the concentrations of 2-hexanol and methanol on the rate of the one-pot synthesis.Methods. One-pot synthesis was studied in a toluene medium in a steel batch reactor designed to operate at elevated pressure and equipped with a glass insert, a magnetic stirrer, a sampler, and gas input and discharge devices. Samples of the reaction mass were taken during the combined process and were analyzed by means of gas–liquid chromatography with a flame ionization detector.Results. The possibility of one-pot combination was demonstrated for 2-hexanol dehydration catalyzed by methanesulfonic acid, as well as for the isomerizing alkoxycarbonylation of the resulting 2-hexene with 2-hexanol and CO, catalyzed by the Pd(PPh3)2Cl2–XANTPHOS–methanesulfonic acid system. The dependencies of the rates of the dehydration of 2-hexanol and the formation of esters of C7 carboxylic acids on the concentration of 2-hexanol were shown to pass through a maximum. The possibility of the one-pot process was proved for the synthesis of esters from 2-hexanol, methanol, and CO with the predominant formation of heptanoic acid esters in the presence of the above catalytic system. The rates of dehydration of 2-hexanol and the formation of 2-hexyl esters of C7 carboxylic acids were found to decrease with increasing the concentration of methanol in the reaction mass. Under mild conditions (temperature 115°C, CO pressure 3 MPa) with the addition of methanol, the total fraction of 2-hexyl and methyl heptanoic acid esters among C7 carboxylic acid esters was determined to be 85.5%.Conclusions. The reactions of intramolecular acid–catalytic dehydration of 2-hexanol and isomerizing alkoxycarbonylation of the resulting 2-hexene, catalyzed by the Pd(PPh3)2Cl2–XANTPHOS–methanesulfonic acid system, can be performed as a one-pot process. Methanesulfonic acid simultaneously functions as a catalyst for the dehydration of 2-hexanol and a cocatalyst for the palladium–phosphine system for the alkoxycarbonylation of hexenes. In the presence of the Pd(PPh3) 2Cl2–XANTPHOS–methanesulfonic acid catalytic system, processes for the synthesis of heptanoic acid esters from 2-hexanol, methanol, and CO can be combined within one reactor. An increase in the methanol concentration negatively affects the rate of the dehydration of 2-hexanol and the formation of 2-hexyl esters of C7 carboxylic acids. A small amount of methanol in the reaction mass leads to an increase in the fraction of heptanoic acid esters among C7 carboxylic acid esters.

Precisely controlling the product selectivity of a reaction is an important objective in organic synthesis. α‐Ketoamides are vital intermediates in chemical transformations and privileged motifs in numerous drugs, natural products, and biologically active molecules. The selective synthesis of α‐ketoamides from feedstock chemicals in a safe and operationally simple manner under mild conditions is a long‐standing catalysis challenge. Herein, an unprecedented TBD‐switched Pd‐catalyzed double isocyanide insertion reaction for assembling ketoamides in aqueous DMSO from (hetero)aryl halides and pseudohalides under mild conditions is reported. The effectiveness and utility of this protocol are demonstrated by its diverse substrate scope (93 examples), the ability to late‐stage modify pharmaceuticals, scalability to large‐scale synthesis, and the synthesis of pharmaceutically active molecules. Mechanistic studies indicate that TBD is a key ligand that modulates the Pd‐catalyzed double isocyanide insertion process, thereby selectively providing the desired α‐ketoamides in a unique manner. In addition, the imidoylpalladium(II) complex and α‐ketoimine amide are successfully isolated and determined by X‐ray analysis, confirming that they are probable intermediates in the catalytic pathway. [ABSTRACT FROM AUTHOR]

Developing environmentally benevolent and sustainable approaches is a vital objective of research in any field. By upholding these parameters and strategizing the methodology, herein we report the development of a new heterogeneous nanocatalyst based on Schiff base functionalized Pd(II) complex onto titania-coated magnetic nanoparticles [Pd@SB/Fe3O4–TiO2]. The developed catalytic system is well characterized with various techniques such as FE-SEM, TEM, XPS, XRD, TGA, BET, FTIR, VSM, CHN, EDX, and ICP-AES analysis. The catalytic activity of [Pd@SB/Fe3O4–TiO2] for the Suzuki coupling reaction to synthesize biaryls and for the hydrogenation reaction of aromatic nitro compounds to synthesize aromatic amines under sustainable reaction conditions was tested which revealed excellent results. Pd@SB/Fe3O4–TiO2 showed remarkably higher activity than the homogeneous PdCl2 and Pd(OAc)2, which might be due to the presence of electronic synergism between support and Pd. Schiff base functionalization provides excellent support to the palladium as leaching of the metal was not observed. The magnetic core of the catalyst ascertains its easy recoverability, thereby maintaining the sustainability of the reaction. The magnetic catalyst was easily separable with the help of an external magnet and showed very good recyclability for up to six cycles with no appreciable loss in catalytic efficiency. Furthermore, the reported catalyst remains unchanged even after six consecutive runs as established by the FTIR, XPS, and XRD analysis of the recovered catalyst. [ABSTRACT FROM AUTHOR]

An intermolecular annulation reaction of 2‐aryl‐1,3‐indandions with alkynes was reported using Pd(OAc)2 to access spirobi[indene]‐1,3‐diones. Under palladium catalysis, the substrates form a homocoupling dimer intermediate through a catalytic dehydrogenative cross‐coupling process. The palladium(II) species could come from dimer or 2‐aryl‐1,3‐indandion. Notably, this pathway is not typically observed in enol‐directed formal sp3 C−H functionalization/oxidative annulation palladium chemistry. This transformation provides a route to access a class of functionalized spiro carbocyclic indenes. [ABSTRACT FROM AUTHOR]

A novel fluorescent supramolecular polymer (named N3T) has been synthesized resoundingly, which can effectively identify trace amounts of Pd2+ in solution, and then a self-assembled supramolecular catalyst catalyst N3T-Pd was obtained. The N3T-Pd with spherical structure could be used for C–C coupling reactions in an eco-friendly aqueous medium. The catalyst was characterized by NMR, FT-IR, XPS, SEM and fluorescence spectra. The N3T-Pd has prominent stability and recyclability without any decrease of catalytic activity after least five cycles. Notably, the reaction degree of Pd2+ with the supramolecular polymer can be conformed by the fluorescence intensity of the supramolecular polymer. With that, the N3T detection limit (LOD) of Pd2+ was measured by fluorescent titration. Surprisingly, N3T can ultrasensitive detection of Pd2+, the limit of detection was 1.9 × 10−7 M. The self-assembly supramolecular palladium catalyst N3T-Pd has been developed as a novel and efficient catalyst for ligand-free C–C cross-coupling reactions in aqueous at room temperature. [ABSTRACT FROM AUTHOR]

1,2-Dihydroisoquinolines are important compounds due to their biological and medicinal activities, and numerous approaches to their synthesis have been reported. Recently, we reported a facile synthesis of trisubstituted allenamides via N-acetylation followed by DBU-promoted isomerization, where various substituted allenamides were conveniently synthesized from readily available propargylamines with high efficiency. In light of this research background, we focused on the utility of this methodology for the synthesis of substituted 1,2-dihydroisoquinolines. In this study, a palladium-catalyzed cascade cyclization–coupling of trisubstituted allenamides containing a bromoaryl moiety with arylboronic acids is described. When N-acetyl diphenyl-substituted trisubstituted allenamide and phenylboronic acid were treated with 10 mol% of Pd(OAc)2, 20 mol% of P(o-tolyl)3, and 5 equivalents of NaOH in dioxane/H2O (4/1) at 80 °C, the reaction proceeded to afford a substituted 1,2-dihydroisoquinoline. The reaction proceeded via intramolecular cyclization, followed by transmetallation with the arylboronic acid of the resulting allylpalladium intermediate. A variety of highly substituted 1,2-dihydroisoquinolines were concisely obtained using this methodology because the allenamides, as reaction substrates, were prepared from readily available propargylamines in one step. [ABSTRACT FROM AUTHOR]

We explored two methods for synthesizing Pd nanoparticles using three different carbide-derived carbon (CDC) support materials, one of which was nitrogen-doped. These materials were studied for oxygen reduction reaction (ORR) in 0.1 M KOH solution, and the resulting CDC/Pd catalysts were characterized using TEM, XRD, and XPS. The citrate method and the polyol method using polyvinylpyrrolidone (PVP) as a capping agent were employed to elucidate the impact of the support material on the final catalyst. The N-doping of the CDC material resulted in smaller Pd nanoparticles, but only in the case of the citrate method. This suggests that the influence of support is weaker when using the polyol method. The citrate method with CDC1, which is predominantly microporous, led to a higher degree of agglomeration and formation of larger particles in comparison to supports, which possessed a higher degree of mesoporosity. We achieved smaller Pd particle sizes using citrate and NaBH4 compared to the ethylene glycol PVP method. Pd deposited on CDC2 and CDC3 supports showed similar specific activity (SA), suggesting that the N-doping did not significantly influence the ORR process. The highest SA value was observed for CDC1/Pd_Cit, which could be attributed to the formation of larger Pd particles and agglomerates. [ABSTRACT FROM AUTHOR]

The aminocarbonylation of ethyl 2-substituted 5-iodobenzoate has been investigated in the presence of a series of amine nucleophiles, providing an efficient synthetic route for producing various 5-carboxamide and 5-glyoxylamide derivatives of 2-(N-substituted) ethylbenzoates. It was shown, after detailed optimization study, that the formation of amides and α-ketoamides is strongly influenced by the reaction conditions. Performing the reactions of ethyl 2-substituted 5-iodobenzoate with nitrogen nucleophiles at 1 atm of carbon monoxide pressure in the presence of [Pd(η3-C3H5)(μ-Cl)]2 as a palladium source and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) as the base, the corresponding 2-ketocarboxamides were formed as major products (up to 60%). We have characterized the cytotoxicity (MTT test) and SAR of a new class of 2-(N-substituted) ethylbenzoate 5-amides and 5-(α-keto)amides. 5-Glyoxylamido derivatives 9a,b, 14a,d exhibited remarkably good cytotoxic potential on MCF-7 and T98G cancer cell lines. In addition, all the synthesized compounds were found to be non-toxic against normal cells (DF-2). The readily available nitrogen substituted 5-glyoxylamido-2-(N-acetylamino)ethylbenzoates 14a,d may serve as lead molecules for the future research regarding the identification of new anticancer agents. These novel compounds were confirmed to be cyclin-dependent kinase 6 and 9 (CDK6 and 9) inhibitors through in silico molecular modeling studies for the mode of action. [ABSTRACT FROM AUTHOR]

An efficient and stable palladium species catalyst immobilized on functionalized hyper–cross-linked polymers (HCPs-Pd) has been successfully developed and applied in the Suzuki–Miyaura coupling reaction of diverse types of aromatic halides with aryl boronic acid in this work. The results demonstrated that HCPs-Pd exhibited high catalytic activity, which benefited from the microporous structure of the catalyst guaranteed high dispersibility of active palladium, and high specific surface area, large pore volume, good chemical stability. Under optimal reaction conditions, 93.0% of biphenyl yield in the Suzuki–Miyaura reaction with bromobenzene (C6H5Br) and phenylboronic acid (C6H7BO2) as raw material was obtained. The good stability of the HCPs-II-Pd catalyst was verified by five cycles experiments. Perhaps this work provides new insights into the high-yield preparation of aromatic biphenyl compounds employing HCPs-Pd as an efficient and stable catalyst in the Suzuki–Miyaura reaction. [ABSTRACT FROM AUTHOR]

Catalytic formate decomposition under mild conditions is a promising strategy for hydrogen production as an efficient hydrogen carrier. Most of previous studies performed formate decomposition for hydrogen generation in liquid phase or using formate as a promoter for formic acid decomposition, which exhibits relatively low hydrogen energy density by mass. Here, we reported a gel-like formate system for catalytic hydrogen generation under mild conditions. A H 2 yield of 100% with hydrogen energy density by weight of 2.38 wt% was achieved, and the palladium catalyst shows high stability and recyclability for KCOOH gel decomposition. Moreover, the constructed gel-like formate filled in an aluminum cylinder could continuously and steadily supply hydrogen to a 12V/35W fuel cell to drive a LED display. This work may provide a new thought for safe hydrogen storage and production system for hydrogen energy usage in the future. • A gel-like KCOOH system was constructed for hydrogen generation under mild condition. • H 2 yield of 100% with hydrogen energy density by weight of 2.38 wt% was achieved. • The palladium catalyst shows high stability for decomposition of KCOOH gel. • The magnified KCOOH gel can be applied on a fuel cell system. [ABSTRACT FROM AUTHOR]

Abstract Precisely controlling the product selectivity of a reaction is an important objective in organic synthesis. α‐Ketoamides are vital intermediates in chemical transformations and privileged motifs in numerous drugs, natural products, and biologically active molecules. The selective synthesis of α‐ketoamides from feedstock chemicals in a safe and operationally simple manner under mild conditions is a long‐standing catalysis challenge. Herein, an unprecedented TBD‐switched Pd‐catalyzed double isocyanide insertion reaction for assembling ketoamides in aqueous DMSO from (hetero)aryl halides and pseudohalides under mild conditions is reported. The effectiveness and utility of this protocol are demonstrated by its diverse substrate scope (93 examples), the ability to late‐stage modify pharmaceuticals, scalability to large‐scale synthesis, and the synthesis of pharmaceutically active molecules. Mechanistic studies indicate that TBD is a key ligand that modulates the Pd‐catalyzed double isocyanide insertion process, thereby selectively providing the desired α‐ketoamides in a unique manner. In addition, the imidoylpalladium(II) complex and α‐ketoimine amide are successfully isolated and determined by X‐ray analysis, confirming that they are probable intermediates in the catalytic pathway.

Imidazo[1,2-a]pyridines and especially their amide derivatives exhibit a wide range of favourable pharmacological properties. In this work, Pd-catalysed carbonylation was used for the first time for the introduction of the carboxamide moiety into positions 6 or 8. A recyclable Pd catalyst, with palladium immobilised on a supported ionic liquid phase decorated with pyridinium ions, was used efficiently for the conversion of 6- or 8-iodo derivatives to the products. In the case of 6-iodo derivatives, a competing mono- and double carbonylation could be observed in the reactions of aliphatic amines as nucleophiles, but under the proper choice of reaction conditions, good-to-excellent selectivities could be achieved towards either the corresponding amides or α-ketomides. The heterogeneous catalyst showed excellent recyclability and low Pd-leaching.

Suzuki−Miyaura cross‐coupling reactions are used to modify the tyrosine residues on Bombyx mori silkworm silk proteins using a water‐soluble palladium catalyst. First, model reactions using tyrosine derivatives are screened to determine optimal reaction conditions. For these reactions, a variety of aryl boronic acids, solvents, buffers, and temperature ranges are explored. Qualitative information on the reaction progress is collected via high‐performance liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR). Optimized reactions are then applied to silk proteins. It is demonstrated the ability to modify silk fibroin in solution by first iodinating the tyrosine residues on the protein, and then carrying out Suzuki‐Miyaura reactions with a variety of boronic acid derivatives. Modification of silk is confirmed with NMR, ion‐exchange chromatography (IEC), UV‐vis, and infrared spectroscopy (IR). [ABSTRACT FROM AUTHOR]

In order to increase the catalytic activity of the Pd(II)-complexes in the alcoxycarbonylation of 1-olefins, the presence in solution of a strong Brönsted acid together with a phosphine ligand is usually required. From an industrial point of view, such two additives, however, influenced the sustainability of the process mainly caused by the related corrosion of the reaction vessel and the toxicity of the phosphine ligand. In this paper, the methoxycarbonylation of 1-octene has been efficiently carried out by using the [Pd(TsO)2(PPh3)2]/FeCl3 catalyst system. The catalyst is very active also without addition of PPh3, reaching the TON of ca. 1300 (mol/mol) in 2 hours by using the Fe(III)/Pd(II) = 400/1 (mol/mol) system. Such value is higher than the values obtained by using the traditional strong Brönsted acid TsOH or other Lewis acid such as AlCl3, in the presence of PPh3. The reaction takes place with the formation of two isomeric products of linear and branched structures with a yield towards the linear isomer of ca. 80%. [ABSTRACT FROM AUTHOR]

This document provides detailed information on the synthesis and characterization of three chemical compounds obtained through a palladium-catalyzed elimination reaction. The compounds were synthesized using specific reagents and conditions, and their structures were confirmed using various analytical techniques. The document also acknowledges the assistance of the Instrumental Analysis Center at Osaka University and includes supporting information for further reference. This information can be valuable for researchers studying these compounds or related topics. [Extracted from the article]

N-(4-hydroxyphenyl)acetamide (commonly named paracetamol or acetaminophen) is a target molecules for many industries that produce chemicals for pharmaceutical applications. The industrial processes, however, use multistep procedures with low overall yield and/or severe drawbacks and problems in terms of sustainability. In the present paper, a one-pot synthesis is proposed based on the reductive carbonylation of nitrobenzene catalyzed by Pd(II)-complexes. Usually, such a reaction leads to a mixture of different products, including aniline, 4-aminophenol and 1,3-diphenylurea. However, the selectivity towards the possible products strongly depends by the ligands on the Pd(II)-catalyst, but also by the nature of the solvent. According to this, we have found that when the reaction was carried out in dilute acetic acid as a solvent, the [PdCl2(dppb)] catalyst precursor leads in one pot to N-(4-hydroxyphenyl)acetamide. Under optimized reaction conditions, it was possible to produce N-(4-hydroxyphenyl)acetamide with a 85 mol % of selectivity in ca. 5 h.

Herein we describe Pd‐catalyzed cross‐coupling reaction of α‐pinene derivative – pinacarvone O‐methyl oxime (1) with aryl halides (2). Surprisingly, the formation of the C−C coupling product was accompanied by an unexpected opening of the pinene bicyclic structure. The (Z)‐2‐aryl‐4,4,5‐trimethylcyclohexa‐2,5‐dien‐1‐one O‐methyl oxime (3) was formed as the resulting product. The reaction conditions of the developed synthetic procedure were carefully optimized and the reaction mechanism was supposed on the basis of data obtained by structural and computational methods. [ABSTRACT FROM AUTHOR]

N-(4-hydroxyphenyl)acetamide (commonly named paracetamol or acetaminophen) is a target molecules for many industries that produce chemicals for pharmaceutical applications. The industrial processes, however, use multistep procedures with low overall yield and/or severe drawbacks and problems in terms of sustainability. In the present paper, a one-pot synthesis is proposed based on the reductive carbonylation of nitrobenzene catalyzed by Pd(II)-complexes. Usually, such a reaction leads to a mixture of different products, including aniline, 4-aminophenol and 1,3-diphenylurea. However, the selectivity towards the possible products strongly depends by the ligands on the Pd(II)-catalyst, but also by the nature of the solvent. According to this, we have found that when the reaction was carried out in dilute acetic acid as a solvent, the [PdCl2(dppb)] catalyst precursor leads in one pot to N-(4-hydroxyphenyl)acetamide. Under optimized reaction conditions, it was possible to produce N-(4-hydroxyphenyl)acetamide with a 85 mol % of selectivity in ca. 5 h. [ABSTRACT FROM AUTHOR]

Beyond the scope of classical Tsuji‐Trost reaction, an alkene bearing a remote leaving group is not considered as a potential substrate for allylation. The concept of migratory Tsuji‐Trost reaction focuses on the transformations with this type of substrates. Two pathways including olefin migration and leaving group migration to form typical allyl intermediate for following substitution have been explored to demonstrate the feasibility of this new concept. [ABSTRACT FROM AUTHOR]

In the palladium-catalyzed cross-coupling of potassium pentafluorophenyltrifluoroborate with aryl chlorides in the presence of the precursor of SIMes carbene, the yields of pentafluorobiphenyls decrease, whereas the yield of 2,3,4,5,6-pentafluoro-4'-methylbiphenyl from 4-bromotoluene under the same conditions increases. An explanation for this phenomenon and for the intensification of the side hydrodeboration reaction of the initial borate has been proposed. [ABSTRACT FROM AUTHOR]

A new set of microporous organic polymers (POPs) containing diphosphine derivatives synthesized by knitting via Friedel–Crafts has been attained. These amorphous three-dimensional materials have been prepared by utilizing diphosphines, 1,3,5-triphenylbenzene, and biphenyl as nucleophile aromatic groups, dimethoxymethane as the electrophilic linker, and FeCl3 as a promoting catalyst. These polymer networks display moderate thermal stability and high microporosity, boasting BET surface areas above 760 m2/g. They are capable of coordinating with palladium acetate, using the phosphine derivative as an anchoring center, and have proven to be highly efficient catalysts in Suzuki–Miyaura coupling reactions involving bromo- and chloroarenes under environmentally friendly (using water and ethanol as solvents) and aerobic conditions. These supported catalysts have achieved excellent turnover numbers (TON) and turnover frequencies (TOF), while maintaining good recyclability without significant loss of activity or Pd leaching after five consecutive reaction cycles. [ABSTRACT FROM AUTHOR]

Adipic acid (AA), an important precursor to produce nylon‐6, nylon‐6,6, and polyurethanes, can be synthesized from biomass‐derived 1,6‐hexanediol (HDO). Herein, we examined the selective oxidation of 1,6‐hexanediol to adipic acid over Pd/support (support‐ Rice husk ash (RHA), TiO2, C, ZnO, Al2O3, La2O3, Mg(OH)2, and hydroxyapatite (HAP)) catalyst in water at 70 °C under base‐free conditions. Pd/HAP exhibited high catalytic activity among the catalysts explored, affording adipic acid (AA) selectively in 89 % yield with complete conversion of HDO. Investigating these Pd/support catalysts and several control experiments inferred that the basicity of the HAP support concertedly with Pd nanoparticle participated in achieving efficient aerial oxidation of HDO to AA, and hence avoided the need for any additional base additives. Advantageously, Pd/HAP exhibited high activity for gram‐scale reactions and long‐term stability during reusing the catalyst for several cycles without any considerable loss in the catalytic activity. [ABSTRACT FROM AUTHOR]

Pyrolysis of cellulose powder granules impregnated with an aqueous solution of saccharose and palladium nitrate gave granular Pd/C carbons with 1–9 wt % metal. It was shown by X-ray diffraction analysis and electronic microscopy that palladium is present in the carbon matrix in the form of Pd(0) nanoparticles with sizes of 10–30 nm in the main fraction (~95%). Palladium nanoparticles are localized inside the saccharose carbonizate layer and on its surface. An IR spectral study showed that pyrolysis of the cellulose–saccharose powder composite in the presence of palladium nitrate leads to the appearance of ester groups in the carbonizate. An increase in the palladium nitrate content in the cellulose powder leads to lower yields of the carbonizate and larger metal nanoparticles in carbon. The specific catalytic activity of nanoparticles in the model decomposition reaction of hydrogen peroxide was found to be the same for all palladium-containing carbons. [ABSTRACT FROM AUTHOR]

1,2-Dihydroisoquinolines are important compounds due to their biological and medicinal activities, and numerous approaches to their synthesis have been reported. Recently, we reported a facile synthesis of trisubstituted allenamides via N-acetylation followed by DBU-promoted isomerization, where various substituted allenamides were conveniently synthesized from readily available propargylamines with high efficiency. In light of this research background, we focused on the utility of this methodology for the synthesis of substituted 1,2-dihydroisoquinolines. In this study, a palladium-catalyzed cascade cyclization–coupling of trisubstituted allenamides containing a bromoaryl moiety with arylboronic acids is described. When N-acetyl diphenyl-substituted trisubstituted allenamide and phenylboronic acid were treated with 10 mol% of Pd(OAc)2, 20 mol% of P(o-tolyl)3, and 5 equivalents of NaOH in dioxane/H2O (4/1) at 80 °C, the reaction proceeded to afford a substituted 1,2-dihydroisoquinoline. The reaction proceeded via intramolecular cyclization, followed by transmetallation with the arylboronic acid of the resulting allylpalladium intermediate. A variety of highly substituted 1,2-dihydroisoquinolines were concisely obtained using this methodology because the allenamides, as reaction substrates, were prepared from readily available propargylamines in one step.

We explored two methods for synthesizing Pd nanoparticles using three different carbide-derived carbon (CDC) support materials, one of which was nitrogen-doped. These materials were studied for oxygen reduction reaction (ORR) in 0.1 M KOH solution, and the resulting CDC/Pd catalysts were characterized using TEM, XRD, and XPS. The citrate method and the polyol method using polyvinylpyrrolidone (PVP) as a capping agent were employed to elucidate the impact of the support material on the final catalyst. The N-doping of the CDC material resulted in smaller Pd nanoparticles, but only in the case of the citrate method. This suggests that the influence of support is weaker when using the polyol method. The citrate method with CDC1, which is predominantly microporous, led to a higher degree of agglomeration and formation of larger particles in comparison to supports, which possessed a higher degree of mesoporosity. We achieved smaller Pd particle sizes using citrate and NaBH4 compared to the ethylene glycol PVP method. Pd deposited on CDC2 and CDC3 supports showed similar specific activity (SA), suggesting that the N-doping did not significantly influence the ORR process. The highest SA value was observed for CDC1/Pd_Cit, which could be attributed to the formation of larger Pd particles and agglomerates.

[Display omitted] • A novel method for chemodivergent deoxygenative- and alkoxy-carbonylation of alcohols. • With boronic acids as the reaction partner, esters and ketones can be produced selectively. • This protocol features excellent regioselectivity and broad substrate scope. • Highly base-sensitive boronic acid substrates can also be applied under base-free conditions. A method for the chemodivergent deoxygenative- and alkoxy-carbonylation of alcohols with boronic acids via palladium catalysis has been developed. Manipulation of the divergent selectivities depend on simply changing the choice of activators. While a carbodiimide activator promoted the formation of ketones through deoxygenative carbonylation, selectivity for esters via alkoxy carbonylation was observed with an azo activator. Notably, in addition to the broad substrate scope, this base-free strategy enables the use of highly base-sensitive boronic acid substrates. This study contributes to the art of chemoselectivity control in carbonylation chemistry. [ABSTRACT FROM AUTHOR]

In this work, comparative testing of the activity of low-percentage palladium and palladium-nickel catalysts supported on activated diatomite with a commercial nickel catalyst from BASF was carried out in the process of hydrogenation of polyalphaolefins (PAO-4). It has been found that palladium catalysts carry out the process under milder conditions, demonstrate higher activity compared to nickel catalysts, significantly reduce the process time, and provide a higher degree of hydrogenation. The activity of bimetallic catalysts is lower than that of monometallic palladium catalysts. Furthermore, Ni exhibits a reaction temperature of at least 150 °C, while Pd is at least 110 °C. If nickel is a single-use catalyst, then when palladium is used 5 times remains an excellent catalytic activity. Catalyst activity is related to the form of adsorbed hydrogen, and on Pd catalyst hydrogen is weakly bound form, while on Ni hydrogen is strongly bound form. The physicochemical characteristics of catalysts and polyalphaolefin oils also have been determined. [ABSTRACT FROM AUTHOR]

In recent years, phosphine sulfonate ligands have shown unique selectivity and activity in polymerization reactions, [4] but few chiral phosphine ligands with corresponding structures have been reported. Keywords: , -unsaturated sulfonyl fluoride; asymmetric 1,4-addition; palladium catalyst; chiral phosphine EN , -unsaturated sulfonyl fluoride asymmetric 1,4-addition palladium catalyst chiral phosphine 2773 2778 6 08/17/23 20230901 NES 230901 Graph Chiral phosphine is one of the most representative compounds in the family of chiral compounds. To illustrate the utility of the current method, the obtained sulfonyl fluoride compound was converted into a chiral phosphine sulfonate complex. In summary, we have reported the enantioselective addition of diarylphosphines catalyzed by Pd catalyst and obtained a series of chiral phosphine sulfonyl fluoride compounds with high stereoselectivities under relatively mild conditions. [Extracted from the article]

Keywords: methoxylation; palladium catalyst; MIA-directing group; DFT study; hydrogenation EN methoxylation palladium catalyst MIA-directing group DFT study hydrogenation 2547 2553 7 07/31/23 20230817 NES 230817 Graph The I o i -methoxy phenylalanine derivatives have been proven to be medicinal and synthetic valuable fragments, while, their preparation is relatively tricky. By using Raney Ni as a catalyst, a one-pot procedure incorporating the hydrogenation of MIA and protection of free amine proceeded smoothly at room temperature in an 88% yield, providing a short synthetic route for phenylalanine-containing dipeptides B 3 b . Methoxylation, palladium catalyst, MIA-directing group, hydrogenation, DFT study The reaction rate [K(CH SB 3 sb OH)/K(CH SB 3 sb OD)] was 3.07:1, which suggested that the oxhydryl cleavage from CH SB 3 sb OH was involved in the rate-limiting step. [Extracted from the article]

In this study, we focused on the synthesis of tetraazamacrocycles, an essential class of macrocyclic compounds with applications in coordination chemistry, pharmaceuticals, and catalysis. To accomplish this, we developed a ligand‐controlled palladium‐catalyzed allylic substitution approach using bicyclic bridgehead phosphoramidite (briphos) ligands. This approach allowed us to selectively achieve [1+1] and [1+2] allylic aminations between allylic diols and diamines, while avoiding the formation of cyclic [1+1] products. By combining this approach with sequential acetylation and allylic amination, we successfully synthesized tetraazamacrocycles with ring sizes ranging from 16 to 38. These findings demonstrate the potential of a sequential allylation strategy for synthesizing complex molecules with broad applications in the fields of chemistry, pharmaceuticals, and medicine. [ABSTRACT FROM AUTHOR]

Realizing high-efficiency H2 production under practical, mild conditions is essential to meet the requirements to develop this source of ideal clean, alternative energy; thus, this attracted wide spread interest. Catalytic decomposition of formic acid-formate is one of the most widely studied options to achieve this. Herein, we demonstrate H2 production from HCOOK over Pd/C catalysts, in which a flexible content is allowed by modulating the catalyst preparation conditions, reaction conditions, and catalytic characterizations. This experiment not only includes basic chemical kinetics but also guides students to accumulate innovative consciousness through thinking about the structure-activity relationship of catalysts by structural characterization. In addition, this experiment enriches teaching content, improves teaching efficiency, and exercises students' cooperation ability through modular design and group teaching. This project relies on the National Demonstration Center for Experimental Education to build an inter-school resource sharing platform to realize the sharing of experimental data and characterization results that colleges can then use to freely select the required information to enrich students' experiment reports. [ABSTRACT FROM AUTHOR]

In this work, two palladium-based catalysts with either ZSM-5 or Zeolite Y as support material are tested for their performance in selective catalytic reduction of NOx with hydrogen (H2-SCR). The ligh-toff measurements in synthetic exhaust gas mixtures typical for hydrogen combustion engines are supplemented by detailed catalyst characterization comprising N2 physisorption, X-ray powder diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR) and ammonia temperature programmed desorption (NH3-TPD). Introducing 10% or 20% TiO2 into the catalyst formulations reduced the surface area and the number of acidic sites for both catalysts, however, more severely for the Zeolite Y-supported catalysts. The higher reducibility of the Pd particles that was uncovered by H2-TPR resulted in an improved catalytic performance during the light-off measurements and substantially boosted NO conversion. Upon exposition to humid exhaust gas, the ZSM-5-supported catalysts showed a significant drop in performance, whereas the Zeolite Y-supported catalyst kept the high levels of conversion while shifting the selectivity from N2O more toward NH3 and N2. The 1%Pd/20%TiO2/HY catalyst subject to this work outperforms one of the most active and selective benchmark catalyst formulations, 1%Pd/5%V2O5/20%TiO2-Al2O3, making Zeolite Y a promising support material for H2-SCR catalyst formulations that allow efficient and selective NOx-removal from exhaust gases originating from hydrogen-fueled engines. [ABSTRACT FROM AUTHOR]

Subsequently, the effects of different Cu reagents on the yields of B 5a b and B 6a b were examined under the reaction condition using Pd(PPh SB 3 sb ) SB 4 sb (entries 4-11). Keywords: dihydropyrimidine; fully substituted 2-aryldihydropyrimidine; Pd-catalyzed/Cu-mediated reaction; Liebeskind-Srogl-type cross-coupling reaction; palladium catalyst; copper reagent; aryltributylstannanes; heteroaryltributylstannanes EN dihydropyrimidine fully substituted 2-aryldihydropyrimidine Pd-catalyzed/Cu-mediated reaction Liebeskind-Srogl-type cross-coupling reaction palladium catalyst copper reagent aryltributylstannanes heteroaryltributylstannanes 1996 2004 9 06/16/23 20230704 NES 230704 Dihydropyrimidines (DPs) show a wide range of biological activities suitable for medicinal applications, namely, they display calcium channel inhibitory, [1] anticancer, [3] antibacterial, [5] antifungal, [6] anti-human immunodeficiency virus (HIV), [7] antimalarial, [8] anti-inflammatory, [9] and antioxidation [10] activities. The reaction proceeds smoothly using a low amount (0.5 mol%) of Pd(PPh SB 3 sb ) SB 4 sb and the easily accessible and inexpensive reagent CuBr. Fully substituted 2-aryldihydropyrimidine, Pd-catalyzed/Cu-mediated reaction, Liebeskind-Srogl-type cross-coupling reaction, palladium catalyst, copper reagent, dihydropyrimidine, aryltributylstannanes, heteroaryltributylstannanes. [Extracted from the article]

Supported Pd/CeO2 catalytic systems have been widely investigated in the low-temperature oxidation of CO (LTO CO) due to the unique oxygen storage capacity and redox properties of the ceria support, which highly influence the structural, chemical and electronic state of Pd species. Herein, operando near-ambient pressure XPS (NAP-XPS) technique has allowed the study of a conventional Pd/CeO2 catalyst surface during the CO oxidation reaction under experimental conditions closer to the actual catalytic reaction, unfeasible with other surface science techniques that demand UHV conditions. SEM, HRTEM and XRD analyses of the powder catalyst, prepared by conventional incipient wetness impregnation, reveal uniformly CeO2-loaded Pd NPs of less than 2 nm size, which generated an increase in oxygen vacancies with concomitant ceria reduction, as indicated by H2-TPR and Raman measurements. Adsorbed peroxide (O22−) species on the catalyst surface could also be detected by Raman spectra. Operando NAP-XPS results obtained at the ALBA Synchrotron Light Source revealed two kinds of Pd species under reaction conditions, namely PdOx and PdII ions in a PdxCe1−xO2−δ solution, the latter one appearing to be crucial for the CO oxidation. By means of a non-destructive depth profile analysis using variable synchrotron excitation energies, the location and the role of these palladium species in the CO oxidation reaction could be clarified: PdOx was found to prevail on the upper surface layers of the metallic Pd supported NPs under CO, while under reaction mixture it was rapidly depleted from the surface, leaving a greater amount in the subsurface layers (7% vs. 12%, respectively). On the contrary, the PdxCe1−xO2−δ phase, which was created at the Pd–CeO2 interface in contact with the gas environment, appeared to be predominant on the surface of the catalyst. Its presence was crucial for CO oxidation evolution, acting as a route through which active oxygen species could be transferred from ceria to Pd species for CO oxidation.

Herein, we report a palladium‐catalyzed 'on‐water' methodology for the synthesis of biaryl and m‐teraryl derivatives of aryl carboxamides by selective mono and bis C−H bond functionalization. 8‐aminoquinoline and 2‐thiomethylaniline were used as directing groups for C−H bond functionalization of aryl carboxamides with various aryl and alkyl iodides using 3.0–4.0 mol% of Pd(OAc)2 as catalyst and water as the solvent resulting in 45–97% isolated yields of the mono and bis C−H bond functionalized products. Using an 8‐aminoquinoline carboxamide core, C−H bond functionalization of indole‐3‐carboxylic acid and a late‐stage functionalization of aspirin molecule have also been carried out. Reactions of benzyl/naphthyl picolinamides with aryl iodides gave 60–96% yield of the arylated products using the picolinamide directing group. Moreover, the insoluble nature of products in an aqueous medium enabled us to explore the reusability of the solvent, i. e. water and the catalyst. Control experiments and structural studies were carried out which confirmed the in situ formation of unique palladacycles during the reaction. Removal of the directing groups has been carried out to convert the functionalized products into amines and fluorenone compounds useful in industrial and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed cross-coupling of ortho -alkenyl bromobenzenes and α-aryl-α-diazoesters was realized. The reactions proceeded in moderate to excellent yields with broad substrate scope, providing a straightforward method for the synthesis of 1,1-disubstituted indenes. The reaction is thought to undergo a tandem alkenyl C–H activation/carbene insertion sequence, in which a C,C-pallada(II)cycle is the key intermediate. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new palladium-catalyzed redox-neutral dicarbonylation of terminal alkynes has been reported. • Hydroxylamine acts as both a nucleophile and a potential oxidant. • Maleimides were synthesized in moderate yields under relatively mild conditions. • A new idea for oxidative carbonylation reactions. A palladium-catalyzed redox-neutral dicarbonylation of terminal alkynes has been reported, in which hydroxylamine acts as both a nucleophile and a potential oxidant. Maleimides were synthesized in moderate yields under relatively mild conditions while avoiding the addition of equivalent oxidants. This reaction process involves two key steps: the addition of Pd-H to the terminal alkyne, and the hydroxylamine ester intermediate play the role of an internal oxidant via nucleophilic attack by hydroxylamine. This reaction has a wide range of functional group compatibility, and this internal oxidation reaction process also provided a new idea for other oxidative carbonylation reactions. [ABSTRACT FROM AUTHOR]

We investigated the hydrogen gas sensors based on AlGaN/GaN high electron mobility transistors (HEMTs) for high temperature sensing operation. The gate area of the sensor was functionalized using a 10 nm Pd catalyst layer for hydrogen gas sensing. A thin WO3 layer was deposited on top of the Pd layer to enhance the sensor selectivity toward hydrogen gas. At 200 °C, the sensor exhibited high sensitivity of 658% toward 4%-H2, while exhibiting only a little interaction with NO2, CH4, CO2, NH3, and H2S. From 150 °C to 250 °C, the 10 ppm hydrogen response of the sensor was at least eight times larger than other target gases. These results showed that this sensor is suitable for H2 detection in a complex gas environment at a high temperature. [ABSTRACT FROM AUTHOR]

A series of Schiff‐base functional groups modified MCM‐41 materials have been synthesized and used as the supports of palladium species. The chemical structures of MCM‐41 functionalized by nine Schiff‐base functional groups were characterized by Fourier transform infrared spectroscopy (FT‐IR), whereas their grafting densities of functional groups were achieved from the results of thermogravimetric analysis (TGA) and elemental analysis (EA). Small angle powdered X‐ray (SAX) patterns demonstrate that the ordered mesoporous structures of MCM‐41 were well retained after modification of functional groups and immobilization of Pd2+ cations. Moreover, the regular mesoporous structures of supports and homogeneous dispersions of Pd2+ cations were characterized by transmission electron microscopy (TEM). The positron annihilation lifetime spectroscopic (PALS) results revealed that the electronic and steric factors of functional groups could affect the o‐Ps annihilation properties of support Pd2+ cations. Meanwhile, the catalytic activities of these supported Pd2+ cations chelated by different functional groups were determined by the Heck reaction of iodobenzene with n‐butyl acrylate. At last, the catalytic activities of these supported Pd2+ cations were linearly correlated to their o‐Ps annihilation properties. This result demonstrates that the catalytic activities of supported Pd2+ cations chelated by different functional groups can be readily determined by the o‐Ps annihilation, which can be potentially used in the design and preparation of highly active palladium catalysts. [ABSTRACT FROM AUTHOR]

The effect of MOFs-derived Ce0.3Ni0.7Ox carrier (CN-M) on Pd dispersion states for three-way catalytic (TWC) performance of natural gas vehicles (NGVs) comparing with Ce0.3Ni0.7Ox carrier (CN-C) prepared by citric acid complexation method has been studied. The results showed that the Pd/CN-M catalyst displayed better Pd dispersion (46.3%) and much higher activity for the conversions of CO, NO and CH4. Both T50 and T90 of CO conversion over Pd/CN-M were lower ca. 100 °C than that over Pd/CN-C catalyst, T50 and T90 of NO conversion were same trend with lower degree ca. 150 °C, the CH4 conversion of Pd/CN-M was also much better than that of Pd/CN-C. After thermal aging, the conversions of CO, NO and CH4 of Pd/CN-M had a finite shift with 20–50 °C to high temperature. It showed unique structure, smaller crystal particles, higher metal dispersion, stronger reducibility, and higher adsorbed oxygen (Oα) on Pd/CN-M catalyst in comparison to Pd/CN-C, and dispersion thermal stabilization of Pd particles on Pd/CN-M catalyst was better than that on Pd/CN-C. This work maybe provides a new method for preparing TWCs with high active for NGVs. [ABSTRACT FROM AUTHOR]

One of frequent uses of palladium as catalyst is in the Suzuki-Miyaura cross-coupling reaction, which is one of key reactions in the synthesis of pharmaceuticals, fine chemicals, and electronic device materials. In this work, we explored a unique circulation reactor system for Suzuki-Miyaura CC coupling reaction, in which a robust microflower self-assembled from bistheophyllines heptane (PdBTC7) and PdCl2 were packed in column. Injection of the reactants of bromobenzene and phenylboronic acid 51 times in definite interval in the eluent of water/NaCl/ethanol could give continuously biphenyl product, showing the performance of catalyst in 4498 of TON and 8996 h−1 of TOF.