Presence Of Palladium Acetate Research Articles

Formation and characterization of palladium ethyl 2-aminoazulene-carboxylate complexes

We tried to synthesize an intermolecular cyclic compound with ethyl 2-amino-3-bromoazulene-carboxylate (EABA) using a Buchwald–Hartwig cross-coupling reaction in the presence of palladium acetate and Cs2CO3. The consumption of EABA was confirmed; however, no target compound was produced and a palladium-EABA complex (Pd-EABA) was formed. Pd complexes with diethyl 2-aminoazulene-1,3-carboxylate (DEAA) were synthesized and characterized using single-crystal X-ray structural analysis, nuclear magnetic resonance, Fourier transform infrared (FTIR) spectroscopy, and density functional theory calculations. Oligomer composed of Pd and 2,2′-diamino-1,1′,3,3′-tetrakis(ethoxycarbonyl)-6,6′-biazulene (2DEAA) was synthesized and characterized by matrix assisted laser desorption/ionization time-of-flight mass spectrometry and FTIR. Because of the expansion of the conjugation between p-orbital of the azulenyl moiety and d-orbital of the Pd atom, Pd complexes exhibit bathochromic shifts and hyperchromic effects. When DEAA was mixed with other metal sources (Ti4+, Fe3+, Co2+, Ni2+, Cu2+, Cu+, Zn2+, and Ru3+), no coordination was observed between DEAA and the cations.

Palladium-Catalyzed Direct (Het)arylation Reactions of Benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole and 4,8-Dibromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole).

Palladium-catalyzed direct (het)arylation reactions of strongly electron-withdrawing tricyclic benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) and its 4,8-dibromo derivative were studied; the conditions for the selective formation of mono- and bis-aryl derivatives were found. The reaction of 4,8-dibromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) with thiophenes in the presence of palladium acetate as a catalyst and potassium pivalate as a base, depending on the conditions used, selectively gave both mono- and bis-thienylated benzo-bis-thiadiazoles in low to moderate yields; arenes were found to be inactive in these reactions. It was discovered that direct C-H arylation of benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole with bromo(iodo)arenes and -thiophenes in the presence of Pd(OAc)2 and di-tert-butyl(methyl)phosphonium tetrafluoroborate salt is a powerful tool for the selective formation of 4-mono- and 4,8-di(het)arylated benzo-bis-thiadiazoles. Oxidative double C-H hetarylation of benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole with thiophenes in the presence of Pd(OAc)2 and silver (I) oxide in DMSO was successfully employed to prepare bis-thienylbenzo-bis-thiadiazoles in moderate yields.

Decarboxylative Alkenylation of Imidazo[1,2-a]pyridines Using α,β-Unsaturated Carboxylic Acids via Pd-Catalyzed C–H Functionalization

AbstractAn efficient synthesis of alkenylated imidazo[1,2-a]pyridines has been accomplished using imidazo[1,2-a]pyridines and α,β-unsaturated carboxylic acids adopting C–H functionalization strategy in the presence of palladium acetate, 1,10-phenanthroline, and silver carbonate.

Palladium‐Catalyzed Selective o‐Bromination of Mesoionic 1,3‐Diphenyltetrazolium‐5‐olate: Switching the Directing Group from Nitrogen to Oxygen

AbstractPd‐catalyzed bromination of mesoionic 1,3‐diphenyltetrazolium‐5‐olate (1) was developed. In the presence of palladium acetate (5 mol%), N‐bromosuccinimide (110 mol%), and p‐toluenesulfonic acid (50 mol%) in 1,2‐dichloroethane under reflux, olate 1 underwent bromination to give 1‐(2‐bromophenyl)‐3‐phenyltetrazolium‐5‐olate in a moderate yield as the major product, indicating that the 4‐nitrogen atom acts as a directing group rather than the negatively charged oxygen atom. The X‐ray‐suitable crystals of the corresponding palladacycle were isolated from 1‐mesityl‐3‐phentytetrazolium‐5‐olate and fully characterized. When both the o‐positions of the 3‐phenyl group were occupied by bromine atoms, o‐bromination then occurred at the 1‐phenyl group with the aid of the olate oxygen.

The Mizoroki-Heck reaction in mesoionic 1-butyl-3-methyltetrazolium-5-olate

1-Butyl-3-methyltetrazolium-5-olate (1), a mesoionic compound, exists as a liquid at room temperature and can be used as a polar solvent for the Mizoroki-Heck reaction, wherein it has been proven to be a superior solvent to other solvents. The reaction of iodobenzene with ethyl acrylate in the presence of palladium acetate in mesoionic liquid 1 at 40 °C for 24 h gave ethyl cinnamate in 78% yield in the absence of ligands, while the use of other solvents, such as [bmim][BF4], [bmim][PF6], and DMF gave lower yields (43%, 37%, and 17%, respectively) under the same conditions. Heck-type coupling reactions of electron-deficient or electron-rich aryl iodides and bromobenzenes with olefins (15 examples, 7%–97%) were performed in 1. When a phosphine ligand was added to the reaction mixture, aryl bromides could be used, and the mesoionic liquid containing the catalysts could be reused at least five times.

Development of Routes for the Stereoselective Preparation of β-Aryl-C-glycosides via C-1 Aryl Enones.

A wide range of enones derived from d-glucal, d-galactal, l-rhamnal, d-rhamnal, and l-arabinal underwent Heck-coupling with various arylboronic acids bearing electron-donating and -withdrawing groups in the presence of palladium acetate and 1,10-phenanthroline. These reactions provided synthetically useful C-1 aryl enones in good yields. Many sensitive functional groups as well as protecting groups present in arylboronic acids and enones, respectively, remained intact under optimized conditions. The stereoselective hydrogenation of C-1 aryl enones with Pd-C/H2 provides the β-isomer of 2-deoxy-aryl-C-glycosides in excellent yield. The C-1 aryl enones were also used as precursors for the synthesis of 2-hydroxy-β-aryl-C-glycosides. Regioselective C-2 halogenations and vinylations of C-1 aryl enones were achieved in excellent yields.

Synthesis of hyperbranched polyphenylenes using aryl dichloride monomers by Suzuki polycondensation

Advanced microelectronic fabrication requires stable organic materials that can be used under extreme conditions such as high temperatures. In this study, hyperbranched polyphenylenes (HBPs) were synthesized as stable and soluble polymers via the Suzuki polycondensation of 2‐(3,5‐dichlorophenyl)‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane (Bpin‐Cl) and 3,5‐dichlorophenylboronic acid (BOH‐Cl) in the presence of palladium acetate and 2‐(2′,6′‐dimethoxybiphenyl) dicyclohexylphosphine (SPhos). Soluble polymers having an average molecular weight in the range of 11 000 to 31 000 g/mol were obtained through the polymerization of chloride monomers. The degree of branching was determined to be 50% through inverse‐gated decoupling 13C NMR measurements. The chloride‐terminated HBP showed a temperature of 402°C for 1% weight loss (Td1%) after the sample was purified via precipitation from an N‐methyl‐2‐pyrrolidone (NMP) solution and then thermally treated at 260°C for 3 hours. This thermal stability is higher than that of the HBPs synthesized from the corresponding bromide monomers. Moreover, after heating at 260°C, the sample was found to be soluble in organic solvents. The chlorinated terminal groups played an important role in achieving good solubility after heating. This unique property is attractive for non‐volatile or temporary coating materials used in microelectronic fabrication.

Suzuki-Miyaura Çapraz Eşleşme Reaksiyonunda Katalizör Olarak Heterosiklik Bileşiklerin Uygulanması

Four different benzimidazolium salts (1-4) were prepared in three steps at 80 oC and their structures were elucidated using spectroscopic methods. The compounds (1-4) obtained were tested in in situ medium as catalyst in the carbon-carbon (C-C) bond formation reactions of two different boronic acid derivatives with various aryl halides in the presence of palladium acetate (PdOAc)2 and sodium tertiarybutoxide (NaOBut) as a base. With this reaction, four coupling products (5-8) were synthesized in different yields ranging from 11 to 93%. Compound 2 from the carbene precursors tested in the Suzuki-Miyaura cross-coupling reaction was found to be a more effective catalyst candidate than others.

SYNTHESIS OF ISOMERIC ( E )-[4-(DIMETHYLAMINO)PHENYL]VINYLQUINOXALINES – PRECURSORS FOR A NEW CLASS OF NONLINEAR OPTICAL CHROMOPHORES

Methods are presented for the preparation of isomeric ( Е )-3-, ( Е )-6-, ( Е )-7-[4-(dimethylamino)phenylethenyl]quinoxalin-2-ones and 2-phenylquinoxalines – compounds of ''donor–π-bridge'' type, which serve as precursors for new nonlinear optical chromophores with potentially high first hyperpolarizability values. The introduction of dimethylanilinoethenyl moiety at the position 3 of the quinoxaline system was achieved in good yields by fusion of 3-methyl derivatives with 4-(dimethylamino)benzaldehyde at 220°С in the presence of catalytic amounts of acetic anhydride and pyridine during the synthesis of 3-(dimethylaminophenylethenyl)quinoxalin-2-ones or as a result of condensation of these reactants by the action of 20 М sodium hydroxide solution in the presence of Aliquat 336 during the synthesis of 3-(dimethylaminophenylethenyl)-2-phenylquinoxalines. The introduction of dimethylanilinoethenyl moiety at the positions 6 and 7 was achieved by Heck reaction of p-dimethylaminovinylbenzene with 6- or 7-bromoquinoxalines in the presence of palladium acetate. The structures of isomeric 6-bromo- and 7-bromo-3-methyl derivatives of quinoxalines were confirmed by X-ray structural analysis. Authors: Sirina M. Sharipova, Alina A. Gilmutdinova, Dmitry B. Krivolapov, Zilya R. Khisametdinova, Olga N. Kataeva, Aleksey A. Kalinin

Synthesis of isomeric (E)-[4-(dimethylamino)phenyl]-vinylquinoxalines – precursors for a new class of nonlinear optical chromophores

Methods are presented for the preparation of isomeric (Е)-3-, (Е)-6-, (Е)-7-[4-(dimethylamino)phenylethenyl]quinoxalin-2-ones and 2-phenylquinoxalines – compounds of “donor–π-bridge” type, which serve as precursors for new nonlinear optical chromophores with potentially high first hyperpolarizability values. The introduction of dimethylanilinoethenyl moiety at position 3 of the quinoxaline system was achieved in good yields by fusion of 3-methyl derivatives with 4-(dimethylamino)benzaldehyde at 220°С in the presence of catalytic amounts of acetic anhydride and pyridine during the synthesis of 3-(dimethylaminophenylethenyl)quinoxalin-2-ones or as a result of condensation of these reactants by the action of 20 М sodium hydroxide solution in the presence of Aliquat 336 during the synthesis of 3-(dimethylaminophenylethenyl)-2-phenylquinoxalines. The introduction of dimethylanilinoethenyl moiety at positions 6 and 7 was achieved by Heck reaction of p-dimethylaminovinylbenzene with 6- or 7-bromoquinoxalines in the presence of palladium acetate. The structures of isomeric 6-bromo- and 7-bromo-3-methyl derivatives of quinoxalines were confirmed by X-ray diffraction analysis.

A domino desulfitative coupling and decarboxylative coupling of 3,4-dihydropyrimidine-2-thiones with copper(I) carboxylates

A novel and general carbon-nitrogen and carbon-carbon cross-coupling reaction between 3,4-dihydropyrimidine-2-thiones and copper(I) carboxylates were performed in the presence of palladium acetate. The copper(I) carboxylates act not only as desulfurative reagents but also as sources of carbon nucleophiles. A wide array of highly substituted and functionalized pyrimidines scaffolds were synthesized in good yields.

ChemInform Abstract: Cleavage of C—N Bonds in Guanidine Derivatives and Its Relevance to Efficient C—N Bonds Formation.

AbstractDiarylguanidines are converted to amides by copper(II)‐salts in the presence of palladium acetate.

Synthesis of Non-Symmetrical and Atropisomeric Dibenzo[1,3]diazepines: Pd/CPhos-Catalysed Direct Arylation of Bis-Aryl Aminals

Pd/CPhos-catalysis provides direct arylation/cyclisation of methylene-linked bis-anilines to dibenzo[1,3]diazepines v, which are both non-(C2)-symmetrical and axially chiral. Synthesis of the direct arylation substrates commences with substitution of (N-acyl)anilines to methylene methyl sulfide derivatives, followed by halogenation/de-thiomethylation to N-(chloromethyl)anilines. These are substituted with a second aniline derivative, allowing modular preparation of (ortho-halo)aryl-aminal-linked arenes 4. The C–H functionalising direct arylation conditions were adapted from Fagnou and co-workers: substrates and potassium carbonate were heated in dimethylacetamide in the presence of palladium acetate and an electron-rich and sterically hindered biarylphosphine ligand, here CPhos 5. These conditions delivered the C1-(a)symmetric dibenzo[1,3]diazepine targets, which, due to torsion around the axis of the newly formed biaryl bond, are also intrinsically atropisomeric. The axially twisted scaffold is known to impart special properties to ligands/catalysts when the products are further converted into the corresponding seven-membered ring-containing N-heterocyclic carbenes (e.g. xii and xiv).

Palladium‐Catalyzed Oxidative Acylation of N‐Benzyltriflamides with Aldehydes via CH Bond Activation

AbstractA palladium‐catalyzed ortho‐acylation of N‐benzyltriflamides with aldehydes via direct sp2 CH bond activation is described. Benzylamines with a triflamide directing group in the presence of palladium acetate, acetic acid, and tert‐butyl hydroperoxide as an oxidant can be effectively coupled with aryl and alkyl aldehydes to provide ortho‐acyl‐N‐benzyltriflamides with a high regioselectivity.

Palladium-catalyzed direct oxidative ortho-acylation of anilides with toluene derivatives

Direct oxidative ortho-acylation reaction of anilides with toluene derivatives in the presence of palladium acetate using tert-butyl hydroperoxide as an oxidant was developed. A broad range of diaryl ketones was obtained in good to excellent yields (up to 95%). The plausible mechanism was also proposed.

Synthesis of azamacrocycle stabilized palladium nanoparticles: Controlled size and one-dimensional growth

Palladium nanoparticles (PdNPs) of uniform size in the range of 3–5 nm are prepared in MeOH and MeCN:MeOH by solvent-assisted reduction of palladium acetate in presence of a hexaazamacrocyclic ligand, L1. For the mixed solvent system different ratio of the solvents was tried i.e., 1:1, 1:3 and 3:1. In all cases the concentration and ratio of Pd(II) to L1 was maintained at 2 mM:1 mM. In another experiment NPs were prepared in MeOH by lowering the concentration of L1 to 0.5 mM, where chain-like assemblies of PdNPs was observed. Importantly, the solutions are found to be stable at RT for months. Palladium nanoparticles of uniform size (3-5 nm range) are obtained by solvent-assisted reduction of 2mM palladium acetate in MeOH and MeCN: MeOH in presence of a hexaazamacrocyclic ligand. Chain-like arrangement of the nanoparticles was seen in MeOH medium by lowering the concentration of the ligand from 1 to 0.5 mM.

Labeling of alprenolol with fluorescent aryl iodide as a reagent based on Mizoroki–Heck coupling reaction

A novel fluorescent labeling method for alprenolol was developed based on Mizoroki–Heck coupling reaction. We designed and synthesized fluorescent aryl iodide, 4-(4,5-diphenyl-1 H-imidazol-2-yl)iodobenzene (DIBI) as a labeling reagent. DIBI has a lophine skeleton carrying an iodide atom acting as fluorophore and reactive center, respectively. In order to evaluate the usefulness of DIBI, a high-performance liquid chromatography (HPLC) with fluorescence detection method was developed for the determination of alprenolol as a model compound of terminal double bond. The fluorescent labeling of alprenolol with DIBI was achieved in the presence of palladium acetate as a catalyst, and the labeled alprenolol was detected fluorometrically. In addition, it was found that the fluorescence of DIBI derivative increased and red shifted when compared with that of DIBI. Furthermore, the proposed method could be applied to determine the alprenolol concentration in rat plasma after administration of alprenolol without interferences from biological components. The detection limit (S/N = 3) for alprenolol in rat plasma was 0.74 ng/mL (30 fmol on column).

ChemInform Abstract: Palladium-Catalyzed Synthesis of N-Benzoyl-2-arylethenesulfonamides from (2-(Benzoylsulfamoyl)ethyl)pyridinium Chloride and Aryl Halides.

A new, general synthesis of N-benzoyl-2-arylethenesulfonamides by the reaction of aryl halides including heteroaryl halides with [2-(benzoylsulfamoyl)ethyl]pyridinium chloride in the presence of palladium acetate is described.

ChemInform Abstract: Palladium Catalyzed Reaction of α-Chloromethylnaphthalene with Olefins.

Abstract The reaction of α-chloromethylnaphthalene with various olefins in the presence of palladium acetate produces three different kinds of products. The coupling products with the olefinic bond conjugated to the naphthalene ring are the major products for the reactions of most olefins. An unusual rearrangement product formed via a cyclopalladation intermediate is isolated from the reactions of the two N-vinyl olefins.

Palladium Acetate Catalyzed Oxidative Aromatization of Methylenecyclopropanes

AbstractIsopropenylbiaryl derivatives were produced in moderate to good yields at high temperature from the reaction of methylenecyclopropanes (MCPs) 1 in the presence of palladium acetate under ambient atmosphere by tandem intramolecular C–H and C–C bond activation and aromatization through dehydrogenated rearrangement of MCPs 1. A plausible mechanism has been proposed on the basis of deuterium labeling and control experiments.