PREPARATION OF 8-ALKYL 7-(2-IMIDAZOLINYLAMINO)QUINOLINES VIA PALLADIUM MEDIATED ALKYLATIONS

ABSTRACT

A convenient preparation of 8-alkyl substituted 7-(2-imidazolinylamino)quinolines from the corresponding 8-trifluoromethanesulfonates, utilizing palladium cross-coupling reactions is described.     

S-OXIDATION PRODUCTS OF ALKYLTHIOAMPHETAMINES

ABSTRACT

The preparation of the sulfoxides and the sulfones of two centrally active alkylthioamphetamine salts, (±)-1-(4-methylthiophenyl)-2-aminopropane hydrochloride (2) (MTA · HCl) and (±)-1-(2,5-dimethoxy-4-ethylthiophenyl)-2-aminopropane hydrochloride (7) (ALEPH-2 · HCl), is described.     

Coordination chemistry of palladium(II) and platinum(II) complexes with bioactive Schiff bases: Synthetic,spectral, and biocidal aspects

The Schiff bases, 5-nitro-indol-2,3-dionehydrazinecarboxamide (HSCZ¹) and 7-nitro-indol-2,3- dionehydrazinecarboxamide (HSCZ²), have been synthesized by the condensation of 5-nitro-indol-2,3-dione and 7-nitro-1H-indol-2,3-dione with semicarbazide hydrochloride, respectively. The palladium(II) and platinum( II) complexes have been prepared by mixing palladium chloride and platinum chloride in 1: 2 molar ratios with monobasic bidentate Schiff bases. The ligands and complexes of palladium and platinum have been characterized by elemental analyses, melting point determinations, conductance measurements, molecular weight determinations, and IR, ¹H NMR, and UV spectral studies. These studies showed that the ligands coordinate to the metal atoms in a monobasic bidentate mode, coordinating through oxygen and nitrogen donor systems. Thus, a tetracoordinated environment around the metal atom has been proposed. Both the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties. Plant growth regulating activity of one of the ligands and its complexes has also been recorded on gram plant, and results have been discussed. The article is published in the original.     

Simultaneous Determination of Platinum and Palladium by Second Derivative Spectrophotometry Using 3-(2'-Thiazolylazo)-2, 6-Diaminopyridine as Chromophore Ligand

ABSTRACT

A second derivative spectrophotometric method has been developed for the determination of palladium and platinum in mixtures. The method is based on the formation of the platinum and palladium complexes with 3-(2-thiazolylazo)-2, 6-diaminopyridine, (2, 6-TADAP), in the presence of 1.7 M perchloric acid solution, upon heating at 90° C for 30 min and on the subsequent direct derivative spectrophotometric measurement. The zero-crossing approach and the graphic method were used for determination of platinum and palladium, respectively. Each analyte was determinated in the presence of one another in the ranges 8.9×10^-7 -3.1×10^-5 M for platinum and 4.6×10^-7 - 6.8×10^-5 M, for palladium. The detection limits achieved (3a) were found to be 2.7×10^-7 M of platinum and 1.4×10^-7 M of palladium. The relative standard deviations were in all instances less than 1.0%. In this work is included a study of effect of interferents and the application of the proposed method in synthetic mixtures.     

Spectrophotometric Determination of Palladium by the New Chromogenic Reagent N-Butyl - N'-(Sodium P-Aminobenzenesulfonate) Thiourea

Abstract

A highly sensitive spectrophotometric method for determination of palladium by the new chromogenic reagent (BPT) has been developed. In the presence of cetyltrimethylammonium bromide(CTMAB), palladium reacts with BPT to form a stable yellow complex in HAc-NaAc buffer solution of pH 4.6-5.6 at 294.4 nm with a molar absorptivity of 2.46 x 10⁵ l mol^?1 cm^?1. The method is simple, rapid and sensitive. Trace amounts of palladium in mineral and catalyst samples have been satisfactorily determined by the method.     

Metal-free synthesis of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles via microwave-assisted synthesis pathway

Abstract

A simple, efficient, and metal-free methodology for the preparation of 2-mercaptobenzothiazole and derivatives in excellent yields via microwave-assisted pathway is reported. Our condition provides a convenient protocol for the synthesis of a diverse collection of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles with a very simple purification process. This report provides an alternative protocol for fast access to the wide range of compounds for sequence synthesis and biological studies.     

A Useful,Reliable and Safer Protocol for Hydrogenation and the Hydrogenolysis of O‐Benzyl Groups: The In Situ Preparation of an Active Pd0/C Catalyst with Well‐Defined Properties

A simple, highly reproducible protocol for the hydrogenation of alkenes and alkynes and for the hydrogenolysis of O‐benzyl ethers has been developed. The method features the in situ preparation of an active Pd⁰/C catalyst from Pd(OAc)₂ and charcoal, in methanol. The mild reaction conditions (25 °C) and low catalyst loading required (0.025 mol %), as well as the absence of contamination of the product by palladium residues (<4 ppb), make this a sustainable, useful process for organic chemists. Alternatively, the protocol can be carried out under microwave activation, to shorten the reaction times, with cyclohexene as the hydrogen source.     

One-Pot Synthesis of 1-(E)-Phenylethenyl-1,2,3-Triazoles by Sequential Click-Elimination Reaction from 2-Azido-1-Phenyl-1-(Phenylseleno)Ethane

Abstract

A new convenient one-pot, two-step procedure involving sequential click chemistry and oxidation-elimination reaction for the preparation of 1,4-disubstituted 1,2,3-triazoles bearing 1-(E)-phenylethenyl group from 2-azido-1-phenyl-1-(phenylseleno)ethane is described. The prominent features of this protocol are mild reaction conditions, operational simplicity, and good to high yields of products, as well as avoidance of the isolation of the selenated intermediate.

Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures.     

Efficient Synthesis of Substances Related to Cinacalcet Hydrochloride via Heck Coupling

Efficient synthetic methods to process substances related to cinacalcet hydrochloride 1, generated during the preparation, were described. The compounds were identified as [1-(7,8-dihydro-naphthalen-1-yl)-ethyl]-[3-(3-trifluoromethyl-phenyl)-propyl]-amine hydrochloride 2,[1-(5,6,7,8-tetrahydro-naphthalen-1-yl)-ethyl]-[3-(3-trifluoromethyl-phenyl)-propyl]-amine hydrochloride 3 and [1-(naphthalen-2-yl)-ethyl]-[3-(3-trifluoromethyl-phenyl)-propyl]-amine hydrochloride 4. All were prepared from commercially available materials in several linear steps and characterized by their respective spectral data.     

A Sorbent Extraction Procedure for the Preconcentration of Gold,Silver and Palladium on an Activated Carbon Column

ABSTRACT

A preconcentration method based on the use of an activated carbon column has been established for flame atomic absorption spectrometric determinations of gold, silver and palladium. The analytes were sorbed on the column as a complex of dithiophosphoric acid O, O-diethyl ester (DDTP). The sorbed analytes were eluted through the column with 2M NH₃ in acetone. Quantitative recoveries (≥95 %) for gold, silver and palladium were obtained from acidic solutions. The developing method was successfully applied to the determination of trace amounts of gold, silver and palladium in some samples with satisfactory results (relative standard deviation < 7 %; relative error < 3 %).     

Synthesis,crystal structures,and catalytic activities of palladium imidazole complexes formed by 2-hydroxyethyl group cleavage

N-4,6-dimethyl-2-pyrimidinylimidazole 1 and its hydroxyethyl derivative 1-(2-hydroxyethyl)-3-(4,6-dimethyl-2-pyrimidinyl)imidazolium chloride 2 have been synthesized and characterized. The attempted synthesis of bis(N-heterocyclic carbene)palladium complexes via the direct reaction of 2 with Pd(OAc)₂ results in the unexpected formation of a bis(N-arylimidazole) palladium complex 3. Additionally, the analogous bis(N-methylimidazole) palladium complex 4 has also been synthesized by the above method. Compounds 1–4 were characterized by elemental analysis, IR, and ¹H NMR. Additionally, their crystal structures have been determined by X-ray diffraction. Complexes 3 and 4 were found to be efficient catalysts for the Suzuki reaction.     

Preconcentration and Determination of Trace Palladium with 1, 5-Diphenylcarbazone- Naphthalene as Adsorbent by Atomic Absorption Spectrometry

ABSTRACT|A highly selective, sensitive, rapid and simple atomic absorption spectrometric method has been developed for the determination of trace amounts of palladium in synthetic and real samples. Palladium can be adsorbed on naphthalene-1, 5-diphenyl-carbazone (DPCO) as adsorbent from the large volume of its aqueous solutions in the pH range 2.0 to 0. After filtration, the metal ion was desorbed with 5ml of 0.25M thiourea solution, and determined by AAS.

Alternatively, palladium can be adsorbed on this adsorbent packed in a column and determined similarly. The detection limit is 0.5 μg (signal to noise ratio=2) and the linearity is maintained in concentration range of 1.5-50μg of Pd with a correlation coefficient of 0.9992. Seven replicate determinations on samples containing 2.5 and 20μg of palladium gave the relative standard deviations of 3.6% and 0.81%, respectively. Various parameters such as effect of pH, volume of aqueous phase, shaking time and interference of number of ions on the determination of Pd have been studied in detail to optimize the conditions for its estimation in various synthetic and real samples.     

Zero-Crossing Derivative Spectrophotometric Determination of Mercury(II) And Palladium(II) with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1-3-thiazolidine and Cetyltrimethylammonium Bromide

Abstract

A method is proposed for the simultaneous determination of mercury(II) and palladium(II) by first-derivative spectrophotometry based on the absorption spectra of their complexes with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1,3-thiazolidine [5-(3,4-methoxyhydroxybenzylidene) rhodanine]. Zero-crossing measurement technique is found suitable for the measurement of the first-derivative value at the specified wavelengths. Mercury(II) (0.4-1.4 μg ml^?1) and palladium(II) (0.08 - 1.8 μg ml^?1) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data.     

Convenient Synthesis of 2,7-Diamino-9,9- bis(4-aminophenyl)fluorene

For the synthesis of 2,7-diamino-9,9-bis(4-aminophenyl)fluorene 2 , first 2,7-dinitro-9,9-bis(4-aminophenyl)fluorene 1 was synthesized by the reaction of 2,7-dinitro-9-fluorenone with aniline and aniline hydrochloride. 2 was obtained by the reduction of 1 with hydrazine hydrate and 10% palladium on carbon.     

Synthesis of Well-Defined High-Valent Palladium Complexes by Oxidation of Their Palladium(II) Precursors

The last decade has witnessed the rapid development of high-valent Pd-involved organic transformations. This has also led to a steadily growing number of publications concerning the preparation of isolable and characterizable palladium(III) and palladium(IV) complexes. A variety of one-electron and two-electron oxidants have been employed to give access to high-oxidation-state Pd compounds. Undoubtedly, the study of these stoichiometric reactions has great implications for relevant Pd-mediated catalysis. In this minireview, the focus is on the synthetic approaches to structurally determined Pd^III/IV complexes starting from their Pd^II precursors, and the advances in this research area from early 2010 to late 2019 will be highlighted. Chemical oxidations exploiting various oxidizing agents including 1) hypervalent iodine reagents; 2) halogens; 3) electrophilic fluorination reagents; 4) alkyl/aryl halides; 5) ferrocenium salts; 6) peroxides/O₂; 7) sulfonyl chlorides; and 8) others are covered. A “greener” electrooxidation manner has also been reviewed.     

Interaction of 2-aminopyrimidine with dichloro-[1-alkyl-2-(naphthylazo) imidazole]palladium(II) complexes : Kinetic and mechanistic studies

Background  

The anticancer properties of cisplatin and palladium(II) complexes stem from the ability of the cis-MCl₂ fragment to bind to DNA bases. However, cisplatin also interacts with non-cancer cells, mainly through bonding molecules containing -SH groups, resulting in nephrotoxicity. This has aroused interest in the design of palladium(II) complexes of improved activity and lower toxicity. The reaction of DNA bases with palladium(II) complexes with chelating N,N^/donors of the cis-MCl₂ configuration constitutes a model system that may help explore the mechanism of cisplatin's anticancer activity. Heterocyclic compounds are found widely in nature and are essential to many biochemical processes. Amongst these naturally occurring compounds, the most thoroughly studied is that of pyrimidine. This was one of the factors that encouraged this study into the kinetics and mechanism of the interaction of 2-aminopyrimidine (2-NH₂-Pym) with dichloro-{1-alkyl-2-(α-naphthylazo)imidazole}palladium(II) [Pd(α-NaiR)Cl₂, 1] and dichloro-{1-alkyl-2-(β-naphthylazo)imidazole}palladium(II) [Pd(β-NaiR)Cl₂, 2] complexes where the alkyl R = Me (a), Et (b), or Bz (c).     

Post‐chemiluminescence Method of the Determination of Loperamide Hydrochloride in Human Plasma and Pharmaceutical by Using Dichlorofluorescein as Chemiluminescence Reagent

Abstract

A post‐chemiluminescence (PCL) was observed when loperamide hydrochloride solution was injected into the reaction mixture after the finish of CL reaction of alkaline N‐Chlorosuccinimide (NCS) and dichlorofluorescein. Based on this phenomenon, a simple, sensitive and fast flow injection PCL method was established for the determination of loperamide hydrochloride. The possible mechanism for the PCL reaction was discussed via the investigation of the CL kinetic characteristics, the CL spectra, the fluorescence spectra. The PCL intensity responded linearly to the concentration of loperamide hydrochloride in the range 8.0×10^?10 to 6.0×10^?7 g · ml^?1 with a linear correlation of 0.9995. The detection limit was 4×10^?10 g · ml^?1. The relative standard deviation was 2.4% for 4.0×10^?8 g · ml^?1 loperamide hydrochloride (n=11). This method has been applied to the determination of loperamide hydrochloride in human plasma and pharmaceutical samples with satisfactory results.     

Entry into 6-Methoxy-D(+)-tryptophans. Stereospecific Synthesis of 1-Benzenesulfonyl-6-methoxy-D(+)-tryptophan Ethyl Ester

A strategy for the synthesis of optically active ring-A methoxylated indole alkaloids which employs the Moody azide/Schollkopf chiral auxiliary protocol has resulted in the successful preparation of 1-benzenesulfonyl-6-methoxy-D(+)-tryptophan ethyl ester 16. This amino ester is required for the synthesis of Alstonia bisindole alkaloids including macralstonine 2 via an enantiospecific Pictet-Spengler reaction.     

Synthesis and Characterization of Potential Impurities of the Antimigraine Drug,Rizatriptan Benzoate

Rizatriptan benzoate is a recently developed antimigraine drug used for the treatment of migraines and severe headaches. In the synthesis of rizatriptan benzoate in bulk,various impurities are formed. The present work details the development of a simple and novel process for the preparation of hydrazone impurity (6), rizatriptan N‐oxide (7), rizatriptan dimer (9), desmethyl rizatriptan (13), 5‐(1H‐1,2,4‐triazol‐1‐yl‐methyl)‐1H‐indole‐3‐ethanamine hydrochloride (14), N‐methyl rizatriptan oxalate (15), and impurities.     

Flow Injection Chemiluminescence Determination of Difenidol Hydrochloride Using N-Chlorosuccinimide-Dichlorofluorescein Reaction

Abstract

A flow injection method combined with chemiluminescence detection was described for the determination of difenidol hydrochloride. Strong chemiluminescence was recorded when difenidol hydrochloride was added into the reaction mixture of N-chlorosuccinimide with dichlorofluorescein in alkaline medium. The experimental conditions that affected the chemiluminescence signal, including the concentrations of reactants, the reaction medium, and the instrumental parameters, were carefully optimized. Under the optimum experimental conditions, the enhanced chemiluminescence intensity was linear related to the concentration of difenidol hydrochloride in the range of 4.0 × 10^?9 to 4.0 × 10^?7 g/ml. The detection limit for difenidol hydrochloride was 7 × 10^?10 g/ml, and the sample throughput was 90/h. The relative standard deviation was 2.5% for 5.0 × 10^?8 g/ml difenidol hydrochloride solution (n = 11). The interference of common inorganic ions, excipients, and additives used in pharmaceutical preparation was studied, which showed the method has higher tolerance limit for these substances and has good selectivity. As a preliminary application, the method was applied to the determination of difenidol hydrochloride in tablets, and the satisfactory results were achieved.