XY-ZH compounds as potential 1,3-dipoles. Part 65: atom economic cascade synthesis of highly functionalized pyrimidinylpyrrolidines

The results of the reaction of aminomethyl heterocycles and 4,6-dimethyl-2-formylpyrimidine and of activated secondary amines with different aryl/heteroaryl or aliphatic aldehydes and N-methylmaleimide or maleimide are described. In the former case the reactions gave single diastereomers via endo-transition states whilst the latter gave a mixture of diastereomers, which are believed to arise from anti-dipoles via endo/exo transition states. The stereochemistry of the cycloadducts was determined by ¹H NMR and confirmed by X-ray crystallography.     

Polarographic and spectrophotometric determination of isocarboxazid and tranylcypromine sulphate through treatment with nitrous acid

Two methods are described for the determination of two widely prescribed antidepressants, namely isocarboxazid and tranylcypromine sulphate as the pure drugs and in dosage forms. Both methods involve prior treatment with nitrous acid. In the Spectrophotometric method, the two derivatives obey Beer's law over the concentration range 1–20 g/ml. The derivatives are polarographically reducible withE _1/2 values of –0.84 and –0.73 V for isocarboxazid and tranylcypromine sulphate, respectively. The calibration plots are linear over the range 4.3 × 10^–5–3.0 × 10^–4 and 1.1 × 10^–5–1.65 × 10^–4 mol/1 for isocarboxazid and tranylcypromine sulphate, respectively. The results obtained for assays for the two drugs compare satisfactorily with those given by the official methods.     

Transition Metal Complexes of Azo-8-Hydroxyquinoline Derivatives as Antimicrobial Agents

Some New azo sulphonamide derivatives containing 8-hydroxyquinoline moiety and their complexes with some transition metal ions vz. Fe⁺³, Co⁺², Ni⁺², Cu⁺², and Hg⁺² have been prepared and characterised. The stereochemistry as well as the type of bonding around the metal ions were determined on the basis of microanalysis, IR and UV-VIS spectra, conductivity and magnetic moment measurements; the thermal behaviour of the complexes was also studied. The metal ions coordinate exclusively to the 8-hydroxyquinoline moiety. The biological activity of the complexes was tested against a number of bacteria. Chelation of the metal ions to the ligands induces a remarkable increase in their antimicrobial activity.     

Synthesis and characterization of new poly(ester-amide)s containing diarylidenecyclohexanone in the main chain. Part: II

A new category of poly(ester-amide)s based on diarylidenecyclohexanone in the main chain were synthesized via interfacial polycondensation of two monomers namely: 2,6-bis(4-hydroxybenzylidene) cyclohexanone I and 2,6-bis(4-hydroxy-3-methoxybenzylidene) cyclohexanone II with diacid chlorides IIIa–c. The model compounds were synthesized by reacting one mole of compounds IVa–c with two monomers I and II. The structure of the model compounds was confirmed by correct elemental and spectral analyses. The various characteristics of the resulting polymers including: solubility, viscosity, thermal analysis, and X-ray diffraction analysis were determined and discussed. The majority of the polymers were insoluble in most common organic solvents. The viscosity measurements in dimethylsulfoxide showed the values 0.58–0.79 dl/g. Thermal analysis showed that they were thermally stable up to 500 °C. X-ray analysis showed that the polymers had some degree of crystallinity in the region 2θ = 5–50°.     

Synthesis of N‐Substituted(Thiazol‐2‐ylidene)pyrazol‐5‐amine Derivatives via Condensation of Pyrazolylthioureas with ω‐Bromoacetophenones

1‐Substituted 3‐[3‐methyl‐1H‐pyrazol‐5‐yl]thioureas react with ω‐bromoacetophenones forming N‐substituted(thiazol‐2‐ylidene)pyrazol‐5‐amine derivatives. Rational for these conversations are presented.     

Synthesis of bifunctional thieno[3,2-c]pyrazole,pyrazolothieno[2,3-d]pyrimidin derivatives and their antimicrobial activities

A simple and convenient route was performed for the synthesis of some new heterocyclic compounds based on thieno[3,2-c]pyrazole derivative for antimicrobial evaluation. The key intermediate, 5-amino-3-methyl-1-phenyl-1H-thieno[3,2-c]pyrazole-6-carbohydrazide 3, was prepared by Gewald’s synthesis of Ethyl 5-amino-3-methyl-1-phenyl-1H-thieno[3,2-c]pyrazole-6-carboxylate 2. This intermediate reacted with various reagents to afford different fused and polyfunctional substituted. The structures of these compounds were confirmed by elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectral data. All the new synthesized compounds were screened for various microorganisms such as Aspergillus fumigatus; Geotrichum candidum; Syncephalastrum racemosum (Fungus); Candida albicans (Yeast fungus); Staphylococcus aureus; Bacillus subtilis (as Gram-positive bacteria); Pseudomonas aeruginosa and Escherichia coli (as Gram-negative bacteria) by the disc diffusion method. In general, the novel synthesized compounds possessed moderate to high antimicrobial activity against the previously mentioned microorganisms.     

Photooxidation of bis(ethylxanthato)nickel(II) containing aromatic nitrogen heterocyclic ligands in chloroform

The photochemistry of the complexes [Ni(Etxn)₂(N-N)] [Etxn=ethylxanthate,N-N=2,2-bipyridine(bpy), 4,4-dimethyl-2,2-bipyridine (4,4-Me-bpy), 1,10-phenanthroline (phen) or 2,2-bipyrimidine (bpym)] has been investigated. These complexes were not light sensitive in most solvents such as acetonitrile. Upon irradiation of chloroform solutions of these complexes, a photoredox reaction occurred giving the parent Ni(Etxan)₂. It is suggested that the reactive excited state is of the charge-transfer-to-solvent (CTTS) type. The energy of this state depends on the redox potentials of the solvent. When CHCl₃ as solvent was replaced by the stronger oxidant CCl₄, the photoactive wavelength region was shifted to the red. It was blue shifted when the weaker oxidant CH₂Cl₂ was used. From quantum yield measurements it is concluded that the photostability of the studied complexes decreases in the following order:bpym>phen>bpy>4,4-Me-bpy.

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Photooxidation von Bis(ethylxanthato)nickel(II) mit aromatischen Stickstoffheterocyclen enthaltenden Liganden in Chloroform

Zusammenfassung Es wurde die Photochemie der Komplexe [Ni(Etxn)₂(N-N) [Etxn=Ethylxanthat,N-N=2,2-Bipyridin (bpy), 4,4-Dimethyl-2,2-bipyridin (4,4-Me-bpy), 1,10-Phenanthrolin (phen) oder 2,2-bipyrimidin (bpym)] untersucht. Diese Komplexe waren in den meisten Lösungsmitteln wie etwa Acetonitril nicht lichtsensitiv. Bei Bestrahlung von Chloroformlösungen der Komplexe trat jedoch eine Photoreaktion auf, die zum Stammkomplex Ni(Etxn)₂ führte. Es wird vorgeschlagen, für den reaktiven angeregten Zustand einen Charge-Transfer-zu-Lösungsmittel (CTTS)-Typ anzunehmen. Die Energie dieses Zustands hängt vom Redoxpotential des Lösungsmittels ab. Bei Ersatz von CHCl₃ als Lösungsmittel durch das stärkere Oxidans CCl₄ wurde die photoaktive Wellenlänge nach Rot verschoben. Eine Blauverschiebung ergab sich hingegen, wenn das schwächere Oxidans CH₂Cl₂ verwendet wurde. Aus Messungen der Quantenausbeuten ergab sich die folgende Ordnung nach abnehmender Photostabilität der untersuchten Komplexe:bpym>phen>bpy>4,4-Me-bpy.

     

Reactions of 6-Amino-5-Cyano-3-Methyl-1,4-Diphenyl-1H 4H-Pyrano[2,3-C]Pyrazole and its Methanimidate

Reaction of 6-amino-5-cyano-3-methyl-1,4-diphenyl- 1H,4H-pyrano[2,3-c]pyrazole 1 with triethyl orthoformate in acetic anhydride gave its methanimidate 2, which reacts with primary aliphatic and aromatic amines to give 4,6-dihydro-3-methyl-1,4-diphenyl-6- (alkyl)pyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5(lH)- imine 3 and the starting compound 1 , respectively. Treatment of 1 with o-aminophenol gave 5-(2-benzoxalyl)- 1,4-dihydro-3-methyl-1,4-diphenylpyrano[2,3-c]pyrazol- 6-amine 9.     

Characterization of Copper(II), nickel(II), cobalt(II) and palladium(II) complexes of vicinal oxime-imine ligands; induced chelate isomerism in the same molecule of the nickel(II) complex

Summary Metal complexes of the title ligands were characterized in order to determine the factors influencing the stability of chelate isomerism in the same molecule. The ligands were prepared by 1:1 condensation of isonitrosoacetylacetone (Hiso) with eithero-aminophenol (H₂ isoaph),p-aminophenol (H₂ isopph), or aniline (Hisoanil). The following complexes have been synthesized: [(isoaph)Cu]₄, (Hisoaph)₂Co, (Hisopph)₂ M·nH₂O (M=Ni(II), n=2;M=Pd(II), n=0;M=Co(II), n=2), [(isopph) Cu·H₂O]₂, and (isoanil)₂ M (M=Ni(II), Cu(II), Co(II), or Pd(II)). Both chelate rings in these metal complexes are five-membered. Transimination of one –C=N–C₆H₅ group to –C=NH in (isoanil)₂Ni produced a six-membered chelate ring in (isoim)Ni(isoanil). The induced chelate isomerism is ascribed to intermolecular hydrogen bonding of the imino-hydrogen and the basic nitrogen of the same six-membered chelate ring of an adjacent square planar molecule. Other types of hydrogen bondings with the oximato oxygen (intra- or intermolecular) favour the formation of five-membered chelate rings. Analytical, spectroscopic, and magnetic moment data are in accordance with the suggested formulations.Part of the Ph.D. thesis of Sana M. Imam     

Arylidene Polymers. XVII. Cyclization of Aromatic Poly[dibenzylidenecyclopentanone-Hydrazide] as a Route to Polyheterocyclic 1,3,4-Oxadiazole and 1,2,4-Triazole

A new interesting class of thermal stable arylidene polymers containing 1,3,4-oxadiazole and 1,2,4-triazole moieties in the main chain have been synthesized from aromatic polyhydrazide I. Cyclization of I at 250°C in the absence of solvent was found to be the best pathway for the inclusion of the 1,3,4-oxadiazole moiety in the main chain. Heating of I with aniline, cyclohexyl amine, or 3-amino pyridine at 180°C for 30 h gave the corresponding 1,2,4-triazole polymers III. The introducing effect of different aromatic, cycloalkyl, and heterocyclic amines in III_a-c and IV_a-c on thermal stability behavior was studied by TGA analysis. Moreover, all the polymers were characterized by elemental and spectral analyses, solubility, and viscometry measurements. X-ray diffractograms of the synthesized polymers showed they had less crystallinity than the polyhydrazide precursors.