Synthesis, structure and properties of delocalized transition metal chelates: Diazoketiminato chelates of Co(III) and Pt(II)

The reactions of HL 1 [where HL is 1N-(2-pyridyl-2-methyl)-2-arylazoaniline and is formulated as ArN = NC₆H₄N(H)(CH₂C₅H₄N); Ar = C₆H₅ (for HL¹) or p-MeC₆H₄ (for HL²) or p-ClC₆H₄ (for HL³)] with K₂PtCl₄ and Co(ClO₄)₃ · 6H₂O afforded the (L)PtCl and [(L)₂Co]ClO₄ complexes, respectively. The HL ligands bind the platinum(II) and cobalt(III) centres in a tridentate (N,N,N) fashion, forming new diazoketiminato chelates upon dissociating the amino proton. The X-ray structures of (L³)PtCl and [(L³)₂Co]ClO₄ were determined. Redox properties of the new complexes have been examined.     

Synthesis and intramolecular recyclization of 2,2-dialkyl-6-chloro-4-hydroxymethyl-benzo[<Emphasis Type="Italic">f</Emphasis>]isoindolinium salts

The intramolecular cyclization of dialkyl(2-butynyl-4-hydroxy)[3-(p-chlorophenyl)propargyl]ammonium chlorides, catalyzed by aqueous KOH, was realized. It was shown that the obtained products — 2,2-dialkyl-6-chloro-4-hydroxymethylbenzo[f]isoindolinium chlorides — readily undergo recyclization under the action of a twofold molar amount of KOH in aqueous solution with heating with the formation of 4-dialkylaminomethyl-8-chloro-1,3-dihydronaphtho[1,2-c]furans. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 834–840, June, 2007.     

Synthesis and crystal structure of inclusion compounds: Trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid with boric acid and tetrabutylammonium salt

Two new inclusion compounds (n-C₄H₉)₄N⁺C₁₈-H₁₃O₄ ⁻·B(OH)₃ (1) and (n-C₄H₉)₄N⁺C₁₈H₁₃O₄ ⁻ (2) were prepared and characterized by X-ray crystallography. Crystal data: compound 1, monoclinic P2(1)/c, a = 1.569 9(1) nm, b = 0.995 5(6) nm, c = 2.293 3(1) nm, β = 109.962(3)°, Z = 4, and R ₁ = 0.0434, wR = 0.075 9; compound 2, monoclinic C2/c, a = 1.400 5(3) nm, b = 1,282 1(2) nm, c = 1.765 7(3) nm, β = 100.388(1)°, Z = 4, and R ₁ = 0.0584, wR = 0.096 6. In the crystal structure of 1, the tetramers formed by two trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (EADA) anions and two boric acid molecules were connected through O—H⋯O hydrogen bonds to generate a channel type host lattice. The tetra-n-butylammonium cations were stacked to give two columns within each channel with cross-sectional size of about 2.30 nm × 0.93 nm. In the crystal structure of 2, similar honeycomb host lattices with big size were also formed along the [101] direction by three-dimensional accumulation of EADA anions. The tetra-n-butylammonium cations were accommodated in a zigzag fashion within each channel. Translated from Acta Chimica Sinica, 2006, 64(18): 1904–1910 [译自: 化学学报]     

Novel (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles from (E)- and (Z)-3-styrylchromones: the unexpected case of (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles

An efficient synthetic method for the preparation of (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles has been developed. The reaction of (E)- and (Z)-3-styrylchromones with hydrazine hydrate afforded the corresponding (E)- and (Z)-4-styrylpyrazoles, respectively, saved 4′-nitro-derivatives where both (E)- and (Z)-4′-nitro-3-styrylchromones afforded (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles. The reaction mechanism for these transformations was discussed and the stereochemistry of all products was assigned by NMR experiments.     

Three-component cyclization of hydroxylamino-substituted quinoline with reactive methylene compounds and formaldehyde: new method for the synthesis of 7-(isoxazolidin-2-yl)-6-fluoroquinolones

A one-step procedure was developed for the synthesis of new 6-fluoro-7-(isoxazolidin-2-yl)-4-oxo-1,4-dihydroquinolines. The procedure is based on the 1,3-dipolar cycloaddition of the azomethine oxide and 1,1-disubstituted alkenes, which are generated in situ from 6-fluoro-7-hydroxylamino-4-oxo-1,4-dihydroquinoline-3-carboxylic acid and CH-active compounds (dialkyl malonates, ethyl acetoacetate), respectively, in the presence of formaldehyde at 100—120 °C.     

POLYBINAPHTHYLS INCORPORATING (R)-2,2''''-BINAPHTHO-20-CROWN-6 AND NAPHTHYL MOITIES

Chiral polymer was synthesized by the polymerization of (R)-6,6'-bistributylstannyl-2,2'-binaphtho-20-crown-6 (M-1) with 1,4-dibromo-2,3-bisbutoxy-naphthyl (M-2) by Pd(PPh3)4 catalyzed Stille coupling reaction. Both monomer and polymer were analyzed by NMR, MS, FT-IR, UV, polarimetry, DSC-TGA, CD, fluorescent spectroscopy and GPC. The major difference between monomer and polymer is that a long wavelength Cotton Effect was observed for the polymer due to its more extended conjugation in the repeating unit and a highly rigid backbone in the polymer chain. Polymer has strong blue fluorescence due to the efficient energy migration from the extended n-electronic structure of the repeating unit of the polymer to the chiral binaphthyl core and is expected to have potential application in the materials of fluorescent sensors and chiral chromatographic packing for resolution of racemic amino acid.     

Ab initio study of Rg2I− (Rg = Ar,Kr, Xe)

The equilibrium geometries, vibrational frequencies, and dissociation energies of rare gas iodine clusters Rg₂I^?(Rg = Ar, Kr, Xe) were calculated at the Hartree–Fock (HF), second‐order Møller–Plesset (MP2), the coupled cluster method with single and double excitation and a noniterative correction for triple excitations method [CCSD(T)] levels. The title species have bent C_2v structure of about 60° angle. The electron correlation effects and relativistic effects on the geometry and stability were investigated at CCSD(T) level. Both effects stabilize title species. The calculated electron affinities are in good agreement with the experimental results available. The effect of high angular momentum functions (g and h) was studied. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

New synthetic approach to substituted isoindolo[2,1-a]quinoline carboxylic acids via intramolecular Diels-Alder reaction of 4-(N-furyl-2)-4-arylaminobutenes-1 with maleic anhydride

Acylation of substituted 4-(furyl-2)-4-arylaminobut-1-enes with maleic anhydride provided 2-allyl-6-carboxy-4-oxo-3-aza-10-oxatricyclo[5.2.1.0^1,5]dec-8-enes in high yield under mild reaction conditions. The Diels-Alder adducts are formed via an initial amide formation followed by a stereoselective intramolecular [4+2] exo-cycloaddition reaction. Treatment of the tricyclic compounds with phosphoric acid at high temperatures (70-120 °C) promoted cyclic ether opening, intramolecular cyclization and aromatization to give the corresponding tetracyclic compounds, 5,6,6a,11-tetrahydro-10-carboxyisoindolo[2,1-a]quinolines, in moderate yields. The influence of the acid and the reaction temperature on the cyclization reactions are also discussed.     

Copper(I) and Gold(I) Complexes with N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine as Ligand: Synthesis and Molecular Structures

Reaction of CuI with 1 or 2 equivalent(s) N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine (BDDP) gives two different complexes, [Cu(I)μ‐(BDDP‐κP,N_py)]₂ ( 1 ) and [Cu(BDDP‐κP,N_py)₂]I ( 2 ), in high yields. The determination of the molecular structure show that both Cu^I atoms are tetrahedrally coordinated, rather than a square‐planar geometry reported for Cr⁰, Ni^II‐BDDP complexes before, which contains a planar tridentate chelate ring system. The introduction of AuCl(tht) (tht = tetrahydrothiophene) into [Cu(BDDP‐κP,N_py)₂]I leads unexpectedly to the formation of a digold complex 2,6‐[(ClAuPh₂P)HN]₂C₅H₃N and dimeric [Cu(I)μ‐(BDDP‐κP,N_py)]₂.     

Diels-Alder reaction of optically active (E)-γ-keto-α,β-unsaturated p-tolylsulfoxides with cyclopentadiene

The Diels-Alder reaction of enantiomerically pure (E)-γ-keto-α,β-unsaturated p-tolylsulphoxides 3 with cyclopentadiene give four easily separable diastereomers. The effect of several Lewis acids on the reaction was studied, finding a high endo selectivity with respect to the carbonyl group and moderate π-diastereoselectivity using BF₃·Et₂O as catalyst. The reactivity of compounds 3 as well as their endo selectivity are both higher than those observed for the corresponding (E)-3-sulfinylacrylates.