Reaction Of Bromide Research Articles

Cover Feature: Pincer‐Type Mesoionic Carbene Nickel(II) Complexes: Synthesis, Properties, Reactions, and Catalytic Application to the Suzuki–Miyaura Coupling Reaction of Aryl Bromides (Eur. J. Inorg. Chem. 10/2022)

The Cover Feature shows an image of the final product of an elaborately designed pincer complex derived from triazolylidene, which has emerged through a long series of steps from the earth′s abundant nickel mines. The complex has interesting properties provided by the ligand with strong σ-donor and π-acceptor abilities, and bulky substituents. It is also active in the Suzuki-Miyaura coupling of aryl bromides. The crystals are called annabergite and are known to be a landmark in nickel mining. Like this crystal, the complex is expected to become one of the landmarks for the development of organonickel chemistry. More information can be found in the Research Article by K. Matsubara and co-workers.

Pincer‐Type Mesoionic Carbene Nickel(II) Complexes: Synthesis, Properties, Reactions, and Catalytic Application to the Suzuki–Miyaura Coupling Reaction of Aryl Bromides

AbstractTridentate pincer‐type triazolylidene nickel(II) complexes have been prepared and characterized. Despite increasing interest in the new series of mesoionic carbene (MIC) ligands in the field of homogeneous catalysis, pincer‐type MIC metal complexes have rarely been used as catalysts, and there are few studies on MIC nickel complexes. Herein, MIC nickel(II) halide complexes were synthesized from their silver analogues and fully characterized. An anion exchange reaction with silver tetrafluoroborate in acetonitrile gave a dicationic acetonitrile complex in good yield. A comparison of the structures and frontier orbitals between the MIC‐ and NHC‐nickel(II) chloride complexes has revealed that these complexes are comparable in nature. However, their use in the Suzuki–Miyaura (SM) cross‐coupling reaction of aryl bromides with phenylboronic acid requires different conditions to provide sufficient results.

One‐Pot Regio‐ and Diastereoselective Synthesis of Tetrahydro‐α‐carbolines via Cascade Reactions of Iminoindolines with Morita‐Baylis‐Hillman Bromides of Nitroalkenes

AbstractA mild and metal‐free method for the one‐pot synthesis of highly substituted tetrahydro‐α‐carbolines from Morita‐Baylis‐Hillman (MBH) bromides of nitroalkenes and iminoindolines has been demonstrated. Cascade reaction of MBH bromides with tosyliminoindolines occurs with regio‐ as well as diastereoselectivity in a formal [3+3] manner to form various tetrahydro‐α‐carbolines with wide substrate scope under mild conditions. All the products were obtained in high yields within a short reaction time. Also, the synthetic efficiency of the methodology was demonstrated by a gram scale experiment and by further converting them into 3‐nitro‐α‐carbolines.

Pd–Ni bimetallic catalyst supported on dendrimer-functionalized magnetic graphene oxide for efficient catalytic Suzuki-Miyaura coupling reaction

A novel type of dendritic structure was grown on the magnetic graphene oxide nanocomposite surface through thiol-ene click reaction. The resulting nanocomposite was utilized as a support for immobilizing Pd–Ni bimetallic nanoparticles, which were employed in catalytic Suzuki-Miyaura coupling reaction. Transmission electron microscopy and X-ray diffraction analyses confirmed the small size and high dispersity of Pd–Ni nanoparticles. The catalyst efficiently promoted the Suzuki-Miyaura reaction of various aryl bromides and chlorides with arylboronic acids, with excellent yields under mild conditions. The combination of Pd and Ni nanoparticles together with dendritic structure of the catalyst ultimately resulted in the excellent catalytic activity. Not only the existence of dendrimer with high cavities provided the fast adsorption of reactants, but also the synergistic effect between two metals greatly increased the catalytic activity. More importantly, the introduction of Ni significantly increased the catalyst cost-effective. By magnetic separation of the catalyst, it could be retrieved for five times with no remarkable change of activity.

Synthesis of 1‐Trifluoromethylated Propargyl Alcohols by Two Successive Reactions of Cyclopentylmagnesium Bromide in a One‐Pot Manner

AbstractWe have developed a functional‐group‐tolerant one‐pot route to various 3‐substituted 1‐trifluoromethylpropargyl alcohols utilizing two reactions of cyclopentylmagnesium bromide with trifluoroacetic acid esters and terminal alkynes. This new synthetic method involves three successive reactions in a one‐pot process: 1) deprotonation of terminal alkynes with cyclopentylmagnesium bromide, 2) reduction of 2,2,2‐trifluoroethyl trifluoroacetate with cyclopentylmagnesium bromide, and 3) nucleophilic addition of in‐situ‐generated alkynyl Grignard reagents to in‐situ‐formed trifluoroacetaldehyde, leading to the corresponding 3‐substituted 1‐trifluoromethylated propargyl alcohols. This method can be applied to various fluorine‐containing esters as well as terminal alkynes bearing alkyl and aryl groups to give 1‐polyfluoroalkylated propargyl alcohols. The obtained 1‐trifluoromethylpropargyl alcohols with aromatic groups can be converted in good to excellent yields to 1,5‐diaryl‐3‐trifluoromethyl‐dihydropyrazoles, some of the most important motifs in medicine for the treatment of pain and inflammation associated with osteoarthritis in dogs.

Palladium-catalyzed carbene coupling polymerization: synthesis of E-poly(arylene vinylene)s.

The Pd-catalyzed carbene coupling reaction of N-tosylhydrazones and benzyl bromides has been developed into a polymerization process for the first time, providing an efficient method for the synthesis of poly(arylene vinylene)s (PAVs). This method affords PAVs bearing E-vinylene units predominantly. It can also introduce a CF3 group on each vinylene carbon atom in the polymer main chain. The polymerization has a broad scope and the resultant polymers exhibit interesting optical properties and good thermal stabilities.

Silyl-mediated photoredox-catalyzed radical–radical cross-coupling reaction of alkyl bromides and ketoesters

A strategy for cross-coupling between organic bromides and carbonyl compounds is developed by combining photocatalysis and halogen atom transfer using a photocatalyst and tris(trimethylsilyl)silane.

Synthesis and structural characterization of Cd(II) complexes with 2-acetylpyridine-aminoguanidine - a novel coordination mode

The structures of the first two complexes with bidentate coordination of aminoguanidine Schiff base, i.e., 2-acetylpyridine-aminoguanidine (L), are reported. The complex of the formula [Cd2Cl6(HL)2] (1) was obtained in the reaction of warm aqueous solutions of chloride salts of Cd(II), Zn(II) and the ligand, while the reaction of cadmium bromide and the ligand in the presence of deprotonating agent as well as ammonium thiocyanate resulted in the formation of the complex in which Schiff base has both the role of the ligand and the counterion, viz., [HL][Cd(HL)(NCS)2XY]?H2O (2), where X is Cl- or Br-, and Y Br- or SCN-. The complexes were characterized by IR spectroscopy, elemental analysis, conductometric measurements and single crystal X-ray diffraction. The unusual bidentate coordination of the Schiff base lead to significant changes in the geometry of this molecule (from almost planar in free form and as a tridentate ligand to twisted as a bidentate ligand). Besides, in complex 1 relatively rare bridging coordination of Cl- in octahedral Cd(II) is found, while the crystal structure of complex 2 exhibits substitutional disorder, and contains four different anions: [Cd(HL)(NCS)2Br(SCN)]- (ca. 61 %), [Cd(HL)(NCS)2Cl(SCN)]- (ca. 35 %), [Cd(HL)(NCS)2Br2]- (ca. 3 %) and [Cd(HL)(NCS)2ClBr]- (ca. 1 %).

Synthesis of Difluoromethylated Pyrazoles by the [3 + 2] Cycloaddition Reaction of Difluoroacetohydrazonoyl Bromides.

As novel and efficient difluoromethyl building blocks, difluoroacetohydrazonoyl bromides have been synthesized for the first time. The synthetic utility of this reagent for the construction of difluoromethyl organic compounds is demonstrated by their effective regioselective [3 + 2] cycloaddition reactions with ynones, alkynoates, and ynamides. The reactions provide a novel and efficient protocol to access difluoromethyl-substituted pyrazoles in good to excellent yields.

Synthesis of a new hybrid nanocomposite based on vanadium (V) substituted Keggin-type polyoxometalate and polyvinyl alcohol ((TBA)4PMo10V2@PVA) as a nanocatalyst for germination of barley seeds

To investigate a new nanocomposite based on vanadium(V) substituted Keggin-type polyoxometalate as a new nanocatalyst on barley seed germination, nanocomposite (TBA)4PMo10V2@PVA was prepared by reaction of H5PMo10V2O40, tetrabutylammonium bromide (TBA), and polyvinyl alcohol (PVA) at room temperature via sol-gel method. The synthesized hybrid nanocomposite was characterized by FT-IR, UV-vis, XRD, SEM and 31P NMR spectroscopy. The influence of the new organic-inorganic hybrid nanocomposite TBA-PMo10V2@PVA was investigated in germination of barley seeds. In order to compare, several types of polyoxometalates with different concentrations were used to study their effects on growth factors of barley seeds. The obtained results indicate that using ((TBA)4PMo10V2@PVA) with 10 and 100 µM concentrations achieved the most preferred results.

One-pot synthesis of N-benzyl-2-aminobenzoic acid, via ring opening of isatoic anhydride derivative, and its antibacterial screening

2-(N-Benzyl) amino benzoic acid is a bifunctional molecule that could be produced from the reaction between isatoic anhydride and aryl halide. Analogues and derivatives of isatoic anhydride have wide application in pharmaceuticalsincluding antibacterial activity. The aim of this study is to synthesize, characterize and screen N-benzyl isatoic anhydride and 2-(N-benzyl) amino benzoic acid for antibacterial activity. The reaction of isatoic anhydride and benzyl bromide in the presence of potassium carbonate in DMSO at room temperature yielded N-benzyl isatoic anhydride, which under hydrolysis yielded 2-(N-benzyl) amino benzoic acid in which the anhydride ring is opened up. This compound was screened against Gram positive and negative bacteria. Moderate yield of 2-(N-benzyl) amino benzoic acid, a yellow crystal (melting point of 160-162oC, percentage yield 65 %, Rf 0.19) formed by ring opening of N-benzyl isatoic anhydride. The compound showed no antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas pyocyanea, Salmonella typhimurium, Klebsiella aeruginosa and Bacillus subtilis. 2-(N-benzyl)amino benzoic was synthesized, characterized and showed no activity against bacteria.

Synthesis, photophysical properties and catalytic activity of Ƙ3-SCS pincer palladium (II) complex of N,N'-di-tert-butylbenzene-1,3-dicarbothioamide supported by DFT analysis

The title complex [PdCl(L)] (1), is obtained from the reaction of SCS pincer ligand HL (where, HL = N,N'-di-tert-butylbenzene-1,3-dicarbothioamide) with lithium tetrachloropalladate (II) in methanol. The compound 1 is characterized by elemental analysis, FTIR, 1H, and 13C NMR spectroscopy, UV–Vis spectroscopy, and X-ray crystallographic techniques. At room temperature, 1 emits luminescence light of wavelength 460 nm in the solid state upon excitation by UV light of wavelength 280 nm. The average emission lifetime indicates that, both the ligand and complex emission is fluorescence in nature and involves mainly ligand centers π-π* deexcitation. It also shows good catalytic activity towards Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions of aryl bromides with tert-butyl acrylate and p-tolylboronic acid respectively. For both type of reactions, >99% conversion of the substrates is found to occur for electronically activated p-nitro bromobenzene using 1 mol % of 1. Further, modern DFT calculations are performed to decipher the mechanistic insight on the preferable pathways of the Mizoroki-Heck cross-coupling reaction. Stepwise free energy of reactions for various probable reaction pathways suggest that the catalytic route has profound preference for Pd(0)-Pd(II) over Pd(II)-Pd(IV) pathway.

Suzuki–Miyaura Cross-Coupling Reaction with Potassium Aryltrifluoroborate in Pure Water Using Recyclable Nanoparticle Catalyst

AbstractThis paper describes the Suzuki–Miyaura cross-coupling reaction of aryl bromides with potassium aryltrifluoroborates in water catalyzed by linear polystyrene-stabilized PdO nanoparticles (PS-PdONPs). The reaction of aryl bromides having electron-withdrawing groups or electron-donating groups took place smoothly to give the corresponding coupling product in high yields. The catalyst recycles five times without significant loss of catalytic activity although a little bit increase in size of PdNPs was observed after the reaction.

Metal‐Free One‐Pot Synthesis of 2‐(2‐Hydrazinyl) Thiazole Derivatives Using Graphene Oxide in a Green Solvent and Molecular Docking Studies

AbstractAn efficient, one‐pot three‐component reaction in the synthesis of a wide range of 2,4‐disubstituted hydrazinyl thiazole scaffolds in ethanol at room temperature has been developed by the reaction of carbonyl compounds, phenacyl bromides, and thiosemicarbazide, using graphene oxide (GO) as a catalyst. The present catalytic method has many significant advantages such as shorter reaction time, broad substrate scope, low catalyst loading, environmentally benign solvent media, easy handling, and operational simplicity at room temperature. The products are identified based on their various spectroscopic data. The GO catalyst has a high reusability rate and is simple to recover. A mechanistic study suggests that the reaction takes placeviaa thiosemicarbazone intermediate, which is isolated and confirmed in this study using spectroscopic techniques. Thereafter, a molecular docking study has been performed to evaluate the binding affinity of hydrazinyl thiazole derivative as a possible inhibitor on the protein active site of human α‐amylase and glucosamine 6‐phosphate synthase

Continuous Flow Acylation of (Hetero)aryllithiums with Polyfunctional N,N-Dimethylamides and Tetramethylurea in Toluene.

The continuous flow reaction of various aryl or heteroaryl bromides in toluene in the presence of THF (1.0 equiv) with sec‐BuLi (1.1 equiv) provided at 25 °C within 40 sec the corresponding aryllithiums which were acylated with various functionalized N,N‐dimethylamides including easily enolizable amides at −20 °C within 27 sec, producing highly functionalized ketones in 48–90 % yield (36 examples). This method was well suited for the preparation of α‐chiral ketones such as naproxene and ibuprofen derived ketones with 99 % ee. A one‐pot stepwise bis‐addition of two different lithium organometallics to 1,1,3,3‐tetramethyurea (TMU) provided unsymmetrical ketones in 69–79 % yield (9 examples).

Dehalogenative Cross-Coupling of gem-Difluoroalkenes with Alkyl Halides via a Silyl Radical-Mediated Process.

Herein, we describe a convenient general protocol for monofluoroalkenylation reactions of alkyl bromides involving cooperative visible-light photoredox catalysis and halogen abstraction. Mechanistic experiments showed that the products were generated by selective cross-coupling of aliphatic radicals with fluoroalkenyl radicals. Silyl radical-mediated halogen abstraction enabled the protocol to be used for the monofluoroalkenylation of a broad range of alkyl and heteroaryl halides. The protocol could be carried out on a gram scale and was applied to cholesterol, indicating its utility for late-stage monofluoroalkenylation reactions.

Palladium nanoparticle supported on nitrogen‐doped porous carbon: Investigation of structural properties and catalytic activity on Suzuki–Miyaura reactions

AbstractNovel palladium‐doped nanoporous carbon composite material obtained via thermolysis of amorphous zeolitic imidazolate framework (aZIF) was synthesized and used as an efficient catalyst on Suzuki–Miyaura cross‐coupling reactions of aryl bromides. With this developed catalytic system, the Suzuki–Miyaura cross‐coupling reaction was accomplished in aqueous solutions, and biaryls were obtained in good to excellent yields in a short reaction time. The APC‐750@Pd catalyst was characterized by Fourier Transform Infrared spectroscopy (FTIR), X‐ray Diffraction (XRD), Scanning Electron Eicroscopy (SEM), X‐ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Thermal Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), Inductively Coupled Plasma Mass Spectrometry (ICP‐MS) and Brunauer–Emmett–Teller (BET) analysis tecniques. N‐doped porous carbon material (NPC‐1000) was synthesized by thermolysis from aZIF. Activated porous carbon material (APC‐750) was fabricated via fused at 750°C with KOH from NPC‐1000. The APC‐750@Pd was obtained as a result of the interaction of APC‐750 and PdCl2in deionized water. The cross‐coupling reaction of different aryl bromides with phenylboronic acid was investigated to show the potential of the APC‐750@Pd in the Suzuki–Miyaura cross‐coupling reactions. The APC‐750@Pd catalyst could be recycled at least five times with a 15% loss of catalytic efficiency in this catalytic system.

Efficient Regioselective Synthesis of Novel Condensed Sulfur-Nitrogen Heterocyclic Compounds Based on Annulation Reactions of 2-Quinolinesulfenyl Halides with Alkenes and Cycloalkenes.

The preparation of novel reagents 2-quinolinesulfenyl chloride and bromide based on available 2-mercaptoquinoline has been described. This approach opens up opportunities for the introduction of 2-quinolinesulfenyl chloride and bromide into organic synthesis. Regioselective synthesis of novel 1,2-dihydro[1,3]thiazolo[3,2-a]quinolin-10-ium derivatives in high yields has been developed by annulation reactions of 2-quinolinesulfenyl chloride and bromide with alkenes. Condensed tetracyclic products have been obtained by the reactions of 2-quinolinesulfenyl chloride and bromide with cycloalkenes. The opposite regiochemistry in the reactions with styrene, isoeugenol and 1-alkenes was discussed.

Preparation of New Spiropyrazole, Pyrazole and Hydantoin Derivatives and Investigation of Their Antioxidant and Antibacterial Activities.

In this study, the synthesis of new spiropyrazoles, pyrazole and hydantoin heterocycles is reported by three component reactions of parabanic acids, hydrazine derivatives, and phenacyl bromides in the presence of triphenylphosphine as a nucleophile and triethylamine as a base in good to high yields (69-91 %). Evaluation of the synthesized compounds revealed a good to excellent antioxidant activities (37.6-96.2 %) using DPPH inhibitory potency. Among these compounds, hydantoin derivatives displayed higher antioxidant activities (93.7-96.2 %) comparing with spiropyrazoles and pyrazoles. The obtained results showed that Cl and Br substituents on the phenyl ring increased antioxidant activities of the related heterocycles. The antibacterial activities of the synthesized compounds were examined against two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Among the synthesized heterocycles, 2-[1,3-dimethyl-2,5-dioxo-4-(2-oxo-2-phenylethyl)imidazolidin-4-yl]hydrazine-1-carbothioamide exhibited the excellent antibacterial activity against both Gram-positive and Gram-negative bacteria.

Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions

A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.