Reaktionen vonN-Sulfinylverbindungen mit dem 1,2,4-Trithia-3,5-diborolan-Ringsystem und Substitutionsreaktionen am 1,2,4-Trithia-3,5-diborolan und 1,2-Dithia-4-aza-3,5-diborolidin

The reaction of trimethylsilyl- and pentafluorophenyl-N-sulfinylamine respectively with 3,5-dihalogeno-1,2,4-trithia-3,5-diborolanes yields the 1,2-dithia-4-aza-3,5-diborolidines1-3.Tert-butyl-N-sulfinylamine and 3,5-dimethyl-1,2,4-trithia-3,5-diborolane react analogous. OtherN-sulfinylamines however split the disulfane bridge in 3,5-dimethyl-1,2,4-trithia-3,5-diborolane and the 1,4-dithia-2-aza-3,5-diborolidines5A-7(A) are formed. Besides of boroxines, cyclo-2,4,6-trimethyl-1,3-dioxa-5-aza-2,4,6-triboranes and cyclo-2,4,6-trimethyl-1-oxa-3,5-diaza-2,4,6-triboranes are formed as byproducts,8–10 have been isolated. In 1,2,4-trithia-3,5-diborolanes and 1,2-dithia-4-aza-3,5-diborolidines the bromo-atoms can be substituted by alkyl (13, 14), by amino (15–20) and by isothiocyanato groups. The compounds were characterised analytically and spectroscopically (MS; NMR:¹H,¹¹B,¹⁹F,²⁹Si; IR).

     

Alkylation of 3,5-dichloro-2(1H)-pyrazinones using malonate esters

An efficient base-promoted 3-alkylation of 3,5-dichloro-2(1H)-pyrazinones with various malonate esters is described. The method constitutes a simple example of a C-C bond forming process at the 3-position of the pyrazinone core allowing to attain 3-substituted pyrazinones in good to high yields. 3-Alkylation of 3,5-dichloro-2(1H)-pyrazinones with acetoacetic ester was accompanied by further retro-Claisen fragmentation.     

Synthesis,characterisation and structural aspects of some symmetrical organotellurium halides based on Bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride

Bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (2) has been synthesised in good yield by reacting 1-(2-chloroethyl)-3,5-dimethylpyrazole with in situ prepared sodium telluride, Na₂Te in an aqueous solution. A number of new organotellurium halides from bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride have been synthesised by using different halogenating reagents. Reaction of 2 with bromine gave bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride dibromide (5a) in addition to unexpected product bis(2-(4-bromo-3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride dibromide (5b). All compounds were characterized by different spectroscopic techniques viz., ¹H, ¹³C, ¹²⁵Te NMR, Mass spectroscopy, IR and CHN analysis. EDXRF studies have also been employed to confirm the identity of 5a and 5b. Thermal gravimetric analysis of bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (IV) chloride (4) and bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)telluride (IV) iodide (5c) reveals the thermal stability of these molecules above 100°C. The X-ray studies of 5c shows trigonal bipyramidal geometry around tellurium atom and intermolecular secondary interaction viz., C-H π stacking between H23A and C22 showing a supramolecular packing between two molecules.     

Syntheses and crystal structures of rubidium and cesium 3,5-dinitropyrid-2-onate, 3,5-dinitropyrid-4-onate and 3,5-dinitro-4-pyridone-N-hydroxylate

Six complexes, rubidium and cesium 3,5-dinitropyrid-2-onate (2DNPO), 3,5-dinitropyrid-4-onate (4NDPO), 3,5-dinitropyrid-4-one-N-hydroxylate (4DNPNO), were synthesized and characterized by elemental analysis, FT-IR, TG-DTG and X-ray single-crystal diffraction analysis. All the complexes crystallized from water and one of them was a hydrate. Rubidium 3,5-dinitropyrid-4-one-N-hydroxylate was crystallized with the 1?:?2 stoichiometry as Rb[H(4DNPNO)₂] upon absorption of carbon dioxide. The structural determinations showed that the coordination sphere around a metal centre is made up of oxygen atoms and nitrogen atoms, except for the 4DNPNO complexes, where the coordination sphere accommodates exclusively oxygen atoms. The coordination numbers of the metal centers vary from 8, 10, 11 to 12, while the ligands, each employing its pyridone tautomer, link with metal cations. Bridging oxygen atoms play an important role in construction of two- and/or three-dimensional networks of these complexes. Hydrogen bonding contributes to the connectivity within a given sheet in Rb[H(4DNPNO)₂]; aromatic π–π stacking interactions exist only in Cs(4DNPNO). The interactions between metal atoms and ligands are generally very weak. The organization of all layer structures appears to be governed mainly by steric effects and electrostatic forces with very little directional influence of the cations. The thermogravimetric analyses of these complexes showed the following consecutive processes: loss of NO₂ groups, collapse of the pyridyl ring backbones and finally inorganic residue formation. These complexes could be used as probes in template effects of heavy alkali-metal cations in the organization of biorelevant ligands and as environment-friendly energetic catalysts in solid propellants.     

Synthesis and characterization of 3,5-lutidinyl chalcogen and -dichalcogen compounds: X-ray crystal structure of bis(3,5-dimethyl-2-pyridyl) diselenide and 2,6-bis(selenomethyl)-3,5-lutidine

The synthesis of 3,5-lutidinyl chalcogen and -dichalcogen compounds has been described by a method involving selective mono- and dilithiation of 3,5-lutidine (1) ring. The selective mono- and dilithiation of 1 has been achieved by reacting BF₃-complexed 3,5-lutidine (2) with 1 and 2 equiv of LTMP/LDA respectively. The subsequent insertion of elemental selenium followed by aerial oxidation or quenching with iodomethane leads to the formation of bis(3,5-dimethyl-2-pyridyl) diselenide (5) and 2,6-bis(selenomethyl)-3,5-lutidine (7) respectively. In addition, sequential incorporation of sulfur and selenium atom in the same lutidine ring has been reported for the first time. Single-crystal X-ray studies of (5), having a rare C-Se-Se-C torsion angle of 180°(4), and (7) have also been reported.     

Facile Synthesis of 2-Aroyl-3,5-diarylthiophene

Abstract

2-Aroyl-3,5-diarylthiophenes were prepared in very good yields by reaction of 2,4,6-triarylpyrylium salts or 2,4,6-triarylthiopyrylium salts with an aqeous solution of sodium sulfide and iodine at room temperature.     

Interaction of 3,5-di-tert-butyl-o-benzoquinone with secondary amines—a pathway to new sterically hindered N,N-disubstituted o-aminophenols

The interaction of 3,5-di-tert-butyl-o-benzoquinone with secondary amines has been studied. The synthetic procedure was developed in order to synthesize a series of new N,N-disubstituted o-aminophenols. The interaction of 3,5-di-tert-butyl-o-benzoquinone with dimethylamine leads to 2-(N,N-dimethylamino)-4,6-di-tert-butyl-phenol, which is oxidized in the reaction medium by the parent 3,5-di-tert-butyl-o-benzoquinone forming spirocompound 4,5′,6,7′-tetra-tert-butyl-3′-methyl-3′H-spiro[1,3-benzodioxol-2,2′-[1,3]benzoxazole].     

3-[2-(3,5-dimethylpyrazolyl)] succinic anhydride: Synthone for the synthesis of some heterocycles with potential pharmaceutical activity

Summary Aminolysis of 3-[2-(3,5-dimethylpyrazolyl)] succinic anhydride (1) leads to5. Hydrazine hydrate reacts with1a to give 4-(3,5-dimethylpyrazolyl)-1,2,4,5-tetrahydro-3,6-pyridazindione. The structures were confirmed by IR, MS,¹H and¹³C NMR.

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3-[2-(3,5-Dimethylpyrazolyl)]-succinanhydrid, ein Synthon für die Synthese einiger Heterocyclen mit potentieller pharmazeutisch nutzbarer Aktivität

Zusammenfassung Die Aminolyse von 3-[2-(3,5-Dimethylpyrazolyl)]-succinanhydrid (1) führt zu5. Hydrazinhydrat reagiert mit1a zu 4-(3,5-Dimethylpyrazolyl)-1,2,4,5-tetrahydro-3,6-pyridazindion. Die Strukturen wurden mittels IR, MS,¹H-NMR und¹³C-NMR überprüft.

     

Synthesis, crystal structure, spectroscopy and magnetic properties of a dinuclear Cu complex with 3,5-bis(2-pyridyl)pyrazole bridging ligand

A dinuclear Cu^II complex [Cu₂(bpp)₂(H₂O)₂](ClO₄)₂ (1) with 3,5-bis(2-pyridyl)pyrazole (Hbpp), has been synthesized and characterized by elemental analyses, thermal analysis, conductance, UV-vis and IR spectra. The crystal structure of 1, determined by X-ray diffraction technique, reveals that two centrosymmetric Cu^II centers are bridged by a pair of tetradentate anionic bpp ligands, adopting a square-pyramidal environment with the water ligand occupying the axial site. An interesting feature of this structure is the formation of a two-dimensional supramolecular network through O-H?O hydrogen bonds between the water moieties of the cationic [Cu₂(bpp)₂(H₂O)₂]²⁺ subunits and perchlorate anions. The magnetic properties of 1 have been investigated by variable-temperature magnetic susceptibility and EPR measurements. Very strong antiferromagnetic interaction between the Cu^II centers (with H=−JS₁S₂, J=−368.3 cm⁻¹) has been observed, and the magneto-structural correlations was analyzed.     

Syntheses and characterizations of four metal coordination polymers constructed by the pyridine-3,5-dicarboxylate ligand

A series of metal-organic frameworks, namely [Ni(PDB)(H₂O)]_n (1), [Pb(PDB)(H₂O)] · (H₂O) (2), [Co₂(PDB)₂(bpy)₂(H₂O)₄] · 4H₂O (3) and [Co₂(PDB)₂(phen)₂]_n (4) (H₂PDB = pyridine-3,5-dicarboxylic acid, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized based on pyridine-3,5-dicarboxylate acid and two neutral chelate ligands, with different metal ions such as Ni^II, Co^II and Pb^II, under hydrothermal conditions. The framework structures of these polymeric complexes have been determined by the X-ray single crystal diffraction technique. In the four complexes, the pyridine-3,5-dicarboxylate acid ligand exhibits diverse coordination modes, which play an important role in the construction of metal-organic frameworks. The thermal analyses of these four complexes have been measured and discussed. In addition, complex 2 shows strong phosphorescent emission at room temperature and the magnetic measurement of the polymer of 4 reveals a typical antiferromagnetic exchange.     

Reaction between isocyanides and chalcones: an efficient solvent-free synthesis of 5-hydroxy-3,5-diaryl-1,5-dihydro-2H-pyrrol-2-ones

A simple and efficient synthesis of 5-hydroxy-3,5-diaryl-1,5-dihydro-2H-pyrrol-2-ones is described. Heating a mixture of an isocyanide and a 1,3-diaryl-2-propen-1-one under solvent-free conditions produces the title compounds in good to excellent yields.     

Synthesis, structural and spectral properties of novel octakis(3,5-bis-trifluoromethyl-benzylthio) substituted porphyrazine derivatives

[Octakis(3,5-bis-trifluoromethyl-benzylthio)porphyrazinato] magnesium carrying eight (3,5-bis-trifluoromethyl-benzylthio) groups on the peripheral positions have been synthesized by cyclotetramerization of 1,2-bis(3,5-bis-trifluoromethyl-benzylthio)maleonitrile in the presence of magnesium butanolate. Its demetalation by the treatment with trifluoroacetic acid resulted in the metal-free derivative. Further reaction of this product with copper(II) acetate, zinc(II) acetate and cobalt(II) acetate have led to the metallo derivatives M = Cu(II), Zn(II), Co(II). These novel complexes were characterized by elemental analysis, together with FT-IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR, UV-vis and mass spectral data.     

Trans‐3,5‐dihydroperoxy‐3,5‐dimethyl‐1,2‐dioxalane/HBr System as New,Effective, Mild and Non‐toxic Reagent for Synthesis of 2‐Aryl‐1H‐benzothiazoles and 2‐Aryl‐1‐arylmethyl‐1H‐benzimidazoles

Ttrans‐3,5‐dihydroperoxy‐3,5‐dimethyl‐1,2‐dioxalane has been used as new, effective, solid, inexpensive and nontoxic oxidant for in situ generation of Br⁺ from HBr. This system has been applied as catalyst for synthesis of 2‐aryl‐1H‐benzothiazoles and 2‐aryl‐1‐arylmethyl‐1H‐benzimidazoles at room temperature in excellent yields and high purity.     

The nonclassical noncovalent interactions control: A case study of the crystal structure of 3,5-dibromo-2-amino-4,6-dimethylpyridinium tetrahalocuprate [3,5-DBr-2-A-4,6-DMPH]2CuX4 (X = Cl, and Br)

The compound [3,5-dibromo-2-amino-4,6-dimethylpyridinium]₂CuCl₄, (1), was prepared from acidic hydrochloric acetonitrilic medium containing CuCl₂ and 3,5-dibromo-2-amino-4,6-dimethylpyridinium bromide while [3,5-dibromo-2-amino-4,6-dimethylpyridinium]₂CuBr₄, (2), from acidic HBr/Br₂ ethanolic medium containing 4,6-dimethylpyridine and CuBr₂. The ring got dibrominated at 3 and 5 positions in situ. Single-crystal X-ray diffraction proved the compounds to be isomorphous in P − 1. A systematic study of the crystallographic parameters in dibrominated and nonbrominated 2-amino-4,6-dimethylpyridine salts will explain the role of nonclassical noncovalent interaction between aryl bromine and ionic metal bromide in the control of structure.     

Remarkable Chichibabin-type cyclotrimerisation of 3-nitrotyrosine, tyrosine and phenylalanine to 3,5-diphenylpyridine derivatives induced by hypochlorous acid

Reaction of 3-nitrotyrosine with HOCl in aqueous phosphate buffer (pH 7.4) leads to a mixture of extractable products, including 3,5-di(4-hydroxy-3-nitrophenyl)pyridine (15% isolated yield) and 3,5-di(4-hydroxy-3-nitrophenyl)-2-(4-hydroxy-3-nitrophenylmethyl)pyridine (3%) arising by a Chichibabin-like pyridine synthesis via N-chloroimine intermediates. Under the same conditions, phenylalanine gives 3,5-diphenylpyridine in 9% isolated yield, while tyrosine leads to 3,5-di(4-hydroxyphenyl)pyridine (3%) and 3-(3-chloro-4-hydroxyphenyl)-5-(4-hydroxyphenyl)pyridine (3%).     

Preparation of optically pure (3E,5E)-alkyl-2-hydroxy-6-arylhexa-3,5-dienoates by Candida parapsilosis ATCC 7330 mediated deracemisation of the racemates

Biocatalytic deracemisation of a range of racemic (3E,5E)-alkyl-2-hydroxy-6-arylhexa-3,5-dienoates using Candida parapsilosis ATCC 7330 resulted in pure (S)-enantiomers in yields of up to 80% and ee>99%.     

Synthesis and crystal structure of Ni(II) complexes of 2′-(3,5-dibromo-2-hydroxybenzylidene)-3,5-dihydroxybenzoylhydrazide

A new mononuclear nickel(II) complex incorporating a Schiff-base ligand, [NiL₂](DMF)₄ (HL = 2′-(3,5-dibromo-2-hydroxybenzylidene)-3,5-dihydroxybenzoylhydrazide), has been synthesized and characterized by IR, UV-Vis, elemental analysis and X-ray crystal structure analysis. HL is an anionic tridentate ligand. The nickel atom is hexacoordinated with two oxygen atoms from keto group and two oxygen atoms from hydroxy group and two nitrogen atoms from amide, with the two nitrogen atoms occupying the axial positions forming a distorted octahedral coordination sphere.     

Kinetics of the Reaction of 2‐Chloro‐3,5‐dinitrobenzotriflouride with Aniline in Toluene and Methanol‐Toluene Mixed Solvents

Kinetics of the reaction of 2‐chloro‐3,5‐dinitrobenzotriflouride with aniline were studied in toluene, methanol‐toluene binary solvents, benzene and chloroform. The reaction in toluene exhibits third‐order kinetics consistent with aggregates of aniline. Thermodynamic parameters (H^#, (S^# and (G^#are calculated and discussed for the reaction of 2‐chloro‐3,5‐dinitrobenzotriflouride with aniline in methanol‐toluene. Molecular complexes between aniline and the substrate are rejected spectrophotometricaly. The mechanism is studied and compared with the reaction in presence of pyridine. It shows an amine dependence and formation of homo and/or hetero mixed aggregates between aniline and pyridine i.e. dimer mechanism.     

THE CRYSTAL STRUCTURES OF AMMONIUM AND SODIUM 2-AMINO-3,5-DICHLOROBENZOATES

Abstract

The crystal structures of ammonium and sodium 2-amino-3,5-dichlorobenzoates were determined by the X-ray diffraction method. The ammonium salt crystallizes in the monoclinic system (space group P2₁/c) with a = 13.941(3), b = 9.128(3), c = 7.349(2) Å, β = 90.80(3)° and Z = 4. The structure consists of an ammonium cation hydrogen bonded to a carboxylate oxygen of the 2-amino-3,5-dichlorobenzoate anion. The sodium salt of 2-amino-3,5-dichlorobenzoic acid crystallizes in the triclinic system (space group P 1) with a = 8.033(2), 6 = 8.944(2), c = 17.350(3) Å, α = 76.72(3)°, β = 79.69(3)°, γ = 72.54(3)° and Z = 4. The compound is a polymer in which the sodium ions are coordinated by carboxylate oxygen atoms of the organic ligand and water molecules in an octahedral arrangement. IR spectra of the salts are discussed.