Substitutions of fluorine atoms and phenoxy groups in the synthesis of quinoxaline 1,4-di-N-oxide derivatives

The unexpected substitution of fluorine atoms and phenoxy groups attached to quinoxaline or benzofuroxan rings is described. The synthesis of 2-benzyl- and 2-phenoxy-3-methylquinoxaline 1,4-di-N-oxide derivatives was based on the classical Beirut reaction. The tendency of fluorine atoms linked to quinoxaline or benzofuroxan rings to be replaced by a methoxy group when dissolved in an ammonia saturated solution of methanol was clearly demonstrated. In addition, 2-phenoxyquinoxaline 1,4-di-N-oxide derivatives became 2-aminoquinoxaline 1,4-di-N-oxide derivatives in the presence of gaseous ammonia.     

Unexpected reduction of ethyl 3-phenylquinoxaline-2- carboxylate 1,4-di-N-oxide derivatives by amines

The unexpected tendency of amines and functionalized hydrazines to reduce ethyl 3-phenylquinoxaline-2-carboxylate 1,4-di-N-oxide (1) to afford a quinoxaline 1c and mono-oxide quinoxalines 1a and 1b is described. The experimental conditions were standardized to the use of two equivalents of amine in ethanol under reflux for two hours,with the aim of studying the distinct reductive profiles of the amines and the chemoselectivity of the process. With the exception of hydrazine hydrate, which reduced compound 1 to a 3-phenyl-2-quinoxalinecarbohydrazide derivative, the amines only acted as reducing agents.     

Ring Systems Containing Anionic and Cationic Gallium Centers: Structural and Bonding Considerations

The metathetical reaction of 2-(dimethylamino)benzyllithium (Bz(N)Li) with GaCl(3) afforded the salt [Bz(N)(2)Ga][GaCl(4)] (4), the X-ray crystal structure of which revealed a four-coordinate cationic gallium center featuring two Ga-C sigma-bonds and two N-->Ga dative bonds. (Crystal data for 4: monoclinic, space group P2(1)/n, a = 11.519(2) ?, b = 18.254(4) ?, c = 12.506(3) ?, beta = 117.40(3) degrees, V = 2334.6(9) ?(3), Z = 4, R = 0.545). Two Ga.Cl interionic contacts, while somewhat long, are sufficiently strong to render the geometry of 4(+)() roughly midway between tetrahedral and octahedral. Treatment of 1,4-di-tert-butyl-1,4-diazabutadiene (DAB) with 2 equiv of GaCl(3) afforded [(DAB)GaCl(2)][GaCl(4)] (7), which, by means of X-ray analysis, was shown to possess a cation (7(+)()) with localized C=N bonds and N-->Ga dative interactions with a [GaCl(2)](+) moiety. (Crystal data for 7: orthorhombic, space group Pbca, a = 11.882(2) ?, b = 17.289(3) ?, c = 20.424(4) ?, V = 4195.5(11) ?(3), Z = 8, R = 0.460). The structure of 7(+)() is relevant to discussions of the bonding in both neutral DAB complexes of the group 13 elements and the skeletally isoelectronic anion [Me(4)C(4)GaCl(2)](-) (9(-)()). The structure of the [NEt(4)](+) salt of the latter (9) has been determined by X-ray diffraction. (Crystal data for 9: monoclinic, space group P2(1)/n, a = 9.967(1) ?, b = 13.073(2) ?, c = 15.345(2) ?, beta = 96.76(1) degrees, V = 1985.5(4) ?(3), Z = 4, R = 0.721).     

Synthesis of ethers and esters of 1,4-di-N-oxide of 2,3-bis(hydroxymethyl)quinoxalm under conditions of interfacial catalysis

Esters and ethers of the 1,4-di-N-oxide of 2,3-bis(hydroxymethyl)quinoyaline have been obtained under conditions of interfacial catalysis in a chloroform-water system. The catalytic activities of tetrabutylammonium bromide and cetyltriethylammonium bromide have been compared in the synthesis of the acetate, benzoate, and 4-nitrobenzoate of the 1,4-di-N-oxide of 2,3-bis(hydroxymethyl)quinoxaline.St. Petersburg State Technological Institute, St. Petersburg 198013. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 816–820, June, 1994. Original article submitted June 29, 1994.     

L-苯丙氨酸与大环锌配合物的手性拆分、晶体结构与单点能计算

外消旋大环锌配合物［Zn(rac-L)］(ClO₄)₂(L=5,5,7,12,12,14-六甲基-1,4,8,11-四氮杂环十四烷)与L-苯丙氨酸(L-Phe)在弱碱性条件下反应制得单手性配合物［Zn(RR-L)(L-Phe)］(ClO₄)(2),其结构经IR,元素分析,圆二色光谱和X-射线单晶衍射表征。2（CCDC: 1 491 999）属四方晶系,空间群P4₁,晶胞参数a=12.647(11) , b=12.647(11) , c=18.295(3) , β=90 °, V=2 926.2(6) ³, Dc=1.393 g·cm^-3, Z=4, μ=0.977 mm^-1, R₁=0.040 7, wR₂=0.081 5。     

Synthesis and Crystal Structure of a Novel 3D Magnesium(II) Coordination Polymer Constructed by Flexible Benzene-1,4-dioxyacetate

1 INTRODUCTION The coordination chemistry of the alkaline-earth metals has remained a largely underdeveloped area[1, 2]to date. Also calcium(II) and magnesium(II) ions are the essentially biological elements and play an im- portant role in DNA and protein syntheses. Although the transition metal carboxylates have been widely in- vestigated[3, 4], the reports on magnesium complexes with carboxylate ligands are very rare[5]. The flexible phenylenedioxydiacetic acids (BDOAH2), especial…     

Synthesis and Crystal Structure of N,N''''-Diphenyl-3, 6-diethyl-1,4-dihydro-s-tetrazine-1,4-dicarbonamide

1INTRODUCTIONIthasbeenarousedmoreandmoreinterestsinces-tetrazinewasfirstsynthesizedbyHautgschin1900[1].Thesynthesisofdihydroderivativeof3,6-dimethyl-s-tetrazinewasreportedindetailbySkorianetz[2].UsingX-ray,Jennison[3]foundthat1,6-dihydro-s-tetrazinehashom…     

Crystal Structure of Norfloxacin Methanol Solvate: C_(16)H_(18)FN_3O_3·CH_3OH·H_2O

1 INTRODUCTION Norfloxacin (0.16 g, 5 mmol) and PdCl2 (0.02 g) in methanol solution. The brown solution was filtered Norfloxacin (H-Norf = 1-ethyl-6-fluoro-1,4-dihy- and the filtrate was stood undisturbed. Single crys- dro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic tals suitable for X-ray analysis were obtained by slow- acid), a quinolone type compound, is widely used as ly evaporating the methanol solvent at 20 ℃. an antibacterial drug which targets the bacterial type 2. 2 TGA an…     

Planar-chiral metal complexes comprised of square-planar metal and achiral tetradentate ligands: design, optical resolution, and thermodynamics

Planar-chiral palladium complexes {[[N,N'-[1,4-butanediylbis(oxy-7,1-naphthalenediyl)]bis(2-pyridinecarboxamidato)](2-)-κN(1),κN(1)',κN(2),κN(2)']palladium (PdL(4)) and [[2,2'-[1,4-butanediylbis[[(oxy-7,1-naphthalenediyl)imino]methyl]]dipyrrolato](2-)-κN(1),κN(1)',κN(2),κN(2)']palladium (PdL(5))} were synthesized from achiral tetradentate ligands N,N'-[1,4-butanediylbis(oxy-7,1-naphthalenediyl)]bis(2-pyridinecarboxamide) (H(2)L(4)) and N,N'-bis[(1H-pyrrol-2-yl)methylidene]-7,7'-(1,4-butanediyldioxy)bis(1-naphthalenamine) (H(2)L(5)) bearing two dissymmetric bidentate units at both ends and a Pd(II) ion, respectively. The palladium complexes were crystallized in the monoclinic space group P2(1)/n with the unit cell parameters a = 16.5464(6) ?, b = 11.3534(4) ?, c = 17.6697(7) ?, β = 115.5300(10)°, and Z = 4 for PdL(4) and a = 17.2271(8) ?, b = 10.1016(5) ?, c = 17.9361(9) ?, β = 105.6310(10)°, and Z = 4 for PdL(5). The planar-chiral structures of PdL(4) and PdL(5) were confirmed by single-crystal X-ray analyses, resulting in the fact that the crystals were racemic mixtures. The racemic mixtures were successfully resolved by using chiral high-performance liquid-chromatography techniques. Racemizations of the complexes were found to be drastically dependent on the arrangement of the charged or uncharged metal-binding N atoms of the ligands.     

Syntheses, Characterization, and Molecular Mechanics Calculations of Optically Active Silatrane Derivatives

A series of optically active silatrane derivatives, [Si{N(CHRCH(2)O)(CH(2)CH(2)O)(2)}X] (R = Me, i-Pr; X = Ph, OMe) has been synthesized by the reaction of optically active triethanolamine derivatives with XSi(OMe)(3), and characterized by (1)H NMR, (13)C NMR, (29)Si NMR, and mass spectroscopy, and the structures of six compounds have been determined by X-ray analysis. Molecular mechanics methods have also been employed to obtain the energy-minimized structures. The (29)Si NMR chemical shifts and the lengths of Si-N determined by X-ray analysis are sensitive to the bulkiness of the substituent (R). The Si-X bond lengths (X: trans position to nitrogen) do not appreciably differ from one another. The MM2 calculations indicated that the substituent exists in the equatorial position, and the results are in agreement with those of X-ray analysis and (1)H NMR spectroscopy. Crystallographic data: [R = H; X = OMe], C(7)H(15)NO(4)Si, orthorhombic, Pna2(1), a = 13.407(1) ?, b = 8.761(2) ?, c = 8.191(1) ?, Z = 4; [R = Me; X = OMe], C(8)H(17)NO(4)Si, orthorhombic, P2(1)2(1)2(1), a = 10.110(3) ?, b = 11.083(2) ?, c = 9.474(2) ?, Z = 4; [R = i-Pr; X = OMe], C(10)H(21)NO(4)Si, monoclinic, P2(1), a = 8.481(1) ?, b = 7.805(1) ?, c = 10.218(2) ?, beta = 111.31(1) degrees, Z = 2; [R = Me; X = Ph], C(13)H(19)NO(3)Si, orthorhombic, P2(1)2(1)2(1), a = 8.813(1) ?, b = 11.137(2) ?, c = 13.757(1) ?, Z = 4; [R = i-Pr; X = Ph], C(15)H(23)NO(3)Si, orthorhombic, P2(1)2(1)2(1), a = 8.365(1) ?, b = 13.538(2) ?, c = 13.841(2) ?, Z = 4.     

Synthesis, crystal structures, luminescent and magnetic properties of homodinuclear lanthanide complexes with a flexible tripodal carboxylate ligand

Six new homodinuclear lanthanide(III) complexes with a flexible tripodal carboxylate ligand (H(3)L), of formulae [Ln(2)L(2)(DMF)(4)]·4DMF (Ln = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), DMF = N, N-Dimethylformamide) have been synthesized. Among them, 1, 2, 3, 4, 6 were characterized by single-crystal X-ray diffraction, which crystallized in the monoclinic space group P2(1)/n with a = 13.309(2) ?, b = 27.404(4) ?, c = 16.686(3) ?, β = 105.115(2) and V = 5875.2(17) ?(3) for 1, a = 13.3016(5) ?, b = 27.1952(12) ?, c = 16.6339(7) ?, β = 105.030(2) and V = 5811.3(4) ?(3) for 2, a = 13.2797(10) ?, b = 27.072(2) ?, c = 16.6564(13) ?, β = 104.9390(10) and V = 5785.7(8) ?(3) for 3, a = 13.2855(3) ?, b = 27.0074(6) ?, c = 16.6357(3) ?, β = 104.9790(10) and V = 5766.2(2) ?(3) for 4, a = 13.2837(5) ?, b = 26.9105(10) ?, c = 16.6066(6) ?, β = 104.917(2) and V = 5736.3(4) ?(3) for 6. The crystal structures reveal that these complexes are isostructural, and molecules are connected from 0D to 3D supramolecular structures by hydrogen bonds. All of them were characterized by elemental analysis, IR spectroscopy, XRD and TGA. Unusually, non-luminescent Tb(III) complex was obtained. The photophysical property of the Eu(III) complex and the magnetic property of Gd(III) complex are investigated and discussed in detail.     

pBPB共价修饰蝮蛇酸性磷脂酶A2的晶体学数据

The Crystals of acidic phospholipase A2 from the venom of Agkistrodon blomhoffii brevicaudus (i.e. Agkistrodon halys pallas) covalently modified with p-bromo-phenacylbromide were obtained by the method of hanging drop vapor diffusion. Crystallization droplet was composed of 0.06mol?L-1 Na(CH3)2AsO2 (pH=6.5), 24.8% (v/v) 1,4-butanediol, and 4.5mg?mL-1 protein. The crystal data are of a=b=82.82?., c=32.85?, space group P61. 8945 unique reflections with 1.93 ? resolution were measured on a Siemens area detector X-ray diffractometor, of which 8069 reflections having F0 >2σ(F). The experimental results show that the crystals are suitable to a structure analysis of high resolution.     

Systematic investigation of zinc aminoalkylphosphonates: influence of the alkyl chain lengths on the structure formation

With the high-throughput (HT) methodology, the bifunctional aminoalkylphosphonic acids (AAPA) linker molecules 2-aminoethyl- (AEPA), 3-aminopropyl- (APPA), and 4-aminobutylphosphonic acid (ABPA) [HO(3)P-C(n)H(2n)-NH(2) (n = 2-4)] and zinc nitrate were used to synthesize new metal phosphonates in order to investigate the influence of the alkyl chain length on the structure formation. The systematic investigations led to one known (ZnO(3)PC(2)H(4)NH(2)) and six new compounds: one using AEPA, three using APPA, and two using ABPA. The crystal structures of five compounds were determined by single crystal X-ray diffraction, using X-ray powder diffraction (XRPD) data as well as structure modeling employing force field methods. For compound 1, Zn(O(3)P-C(2)H(4)-NH(3))(NO(3))(H(2)O) (monoclinic, Cc, a = 4.799(1) ?, b = 29.342(6) ?, c = 5.631(1) ?, β = 91.59(3)°, V = 792.7(3) ?(3), Z = 4), and compound 2, Zn(2)(OH)(O(3)P-C(3)H(6)-NH(3))(NO(3)) (monoclinic, P2/c, a = 12.158(2) ?, b = 5.0315(10) ?, c = 13.952(3) ?, β = 113.23(3)°, V = 784.3(3) ?(3), Z = 2), the structures were determined using single crystal X-ray diffraction data. The crystal structures of [Zn(O(3)P-C(3)H(6)-NH(2))]·H(2)O (3) (monoclinic, P2(1)/c, a = 9.094(2) ?, b = 5.0118(7) ?, c = 16.067(4) ?, β = 90.38(2)°, V = 732.3(2) ?(3), Z = 4) and Zn(O(3)P-C(4)H(8)-NH(2)) (5) (monoclinic, P2(1)/c, a = 8.570(7) ?, b = 8.378(4) ?, c = 9.902(6) ?, β = 90.94(5)°, V = 710.9(8) ?(3), Z = 4) were determined using XRPD data. The structural model for compound 6, Zn(O(3)P-C(4)H(8)-NH(3))(NO(3))(H(2)O), was established using lattice parameters from XRPD data and following crystal structure modeling employing force field methods. The structures depend strongly on the alkyl chain length n. For n = 2 and 4 isoreticular compounds are observed, while n = 3 leads to new structures. Larger amounts of all compounds were obtained employing scale-up syntheses in a conventional oven as well as in a microwave reactor system. In addition, in situ energy dispersive X-ray diffraction (EDXRD) experiments at 130 °C were performed at beamline F3 at HASYLAB, DESY, Hamburg, to investigate the formation of compounds 2 and 3 as well as the phase transformation of 2 into 3 upon addition of NaOH. All compounds were characterized in detail using X-ray powder diffraction, IR/Raman spectroscopy, and thermogravimetric and elemental analysis.     

Synthesis, spectroscopic characterization and X-ray structure of [1,2a]benzimidazol-2-yl amidine

[1,2a]Benzimidazol-2-yl amidine was synthesized by adding cyclopentanamine to iminoester in ethanol. The structure of amidine 1 was characterized by IR, 1H NMR, 1H-1H NOESY, 13C NMR, DEPT, XHCOR spectra, thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry thermograms (DSC), elementary analysis as well as by X-ray diffraction. The single crystals suitable for X-ray measurement were obtained by recrystallization at room temperature. The amidine group of a model was found to have Z configuration in the crystal. This compound crystallizes in a P2(1)/n monoclinic unit cell with parameters a=12.679(2) ?, b=8.468(3) ?, c=13.108(2) ?, β=96.538(2)°, V=1398.2 ?3 and Z=4.     

Metal complexes with 2,3-bis(diphenylphosphino)-1,4-diazadiene ligands: synthesis,structures, and an intramolecular metal-mediated [4 + 2] cycloaddition employing a benzene ring as a dienophile

2,3-Bis(diphenylphosphino)-1,4-diazadienes RN=C(PPh2)-C(PPh2)=NR (1a, R = 4-tolyl; 1b, R = 4-tert-butylphenyl; 1c, R = mesityl) were used as novel ligands for transition metals. The metal complexes [(1c)Mo(CO)4] (2a), [(1c)[Mo(CO)4]2] (2b), [(1a)Cu(Cl)(PPh3)] (3), and [(1b)[(NiBr2(THF))]2] (4) were characterized by elemental analysis, MS, and 31P[1H], 1H, and 13C NMR spectra (except the paramagnetic complex 4). Additionally, the molecular structure of the complexes in the solid state was determined by single-crystal X-ray diffraction. In 2a and 2b the chelating ligand coordinates via the N,P donor set, whereas in 3 the chelating ligand coordinates via the two P atoms. 4 contains a square-planar (P,P)NiBr2 moiety on the one side of the bridging ligand 1b. On the opposite side the 1,2-dimine unit bonds to another Ni center having octahedral geometry. The bulkier ligand 1c reacts to form the mononuclear compound 5. X-ray diffraction analysis of single crystals shows that 5 contains a quinoxaline derivative with a cyclohexa-1,3-diene ring in the peripheral position. Furthermore, it contains a bis(diphenylphosphino)-ethylene unit coordinating the NiBr2. This arrangement is the result of an intramolecular [4 + 2] cycloaddition between the 1,2-diimine unit (as diheterodiene) and the benzene ring of the 4-tolyl-N substituent (as dieneophile). The same type of ring-closing reaction followed by a tautomerization reaction to form the mononuclear compound 6 occurred by dissolution of the binuclear complex 4 in methanol. This reaction can be used as a simple method for the synthesis of novel 1,2-bis(diarylphosphanyl)ethylenes containing a quinoxaline backbone.     

Halide Effects in the Formation of Four-Coordinate, Cationic Aluminum

This work was conducted as part of a broad-based effort to determine the factors that affect cation formation for organometallic aluminum complexes. In this study the adduct species R(2)AlX.NH(2)(t)Bu (R, X: Me, F (1); Me, Cl (2); Et, Cl (3); Me, Br (4)) and cationic complexes [R(2)Al(NH(2)(t)Bu)(2)]X (R, X: Me, Br (5); Et, Br (6); Me, I (7)) were examined. These complexes demonstrate that the reaction of R(2)AlX with excess NH(2)(t)Bu produces cationic complexes only when X = Br or I. All of the compounds were characterized by melting points, (1)H NMR, IR, elemental analyses, and, in some cases, X-ray crystallography. X-ray data: 2, triclinic, P&onemacr;, a = 6.277(3) ?, b = 8.990(3) ?, c = 10.393(3) ?, alpha = 71.97(1) degrees, beta = 80.25(3) degrees, gamma = 81.97(3) degrees, V = 547.0(4) ?(3), Z = 2, 1032 reflections with F > 4.0 sigma(F), R = 0.0520; 5, monoclinic, P2(1)/c, a = 9.099(1) ?, b = 10.292(1) ?, c = 17.255(2) ?, beta = 104.81(1) degrees, V = 1562.1(3) ?(3), Z = 4, 1464 reflections with F > 4.0 sigmaF, R = 0.0387; 6, monoclinic, P2(1)/c, a = 14.122(2) ?, b = 13.539(2) ?, c = 21.089(2) ?, beta = 107.73(1) degrees, V = 3841.2(9) ?(3), Z = 4, 781 reflections with F > 5.0 sigmaF, R = 0.0873; 7, monoclinic, P2(1)/n, a = 9.071(1) ?, b = 10.529(1) ?, c = 17.714(2) ?, beta = 103.67(1) degrees, V = 1644.0(3) ?(3), Z = 4, 1723 reflections with F > 4.0 sigmaF, R = 0.0451.     

基于草酰胺配体的新型异双核配合物的合成及其晶体结构

以草酰胺铜配合物CuL(H₂L=2,3-二氧-5,6 :13,14-二联苯基-9,10-环己基-1,4,8,11-四氮杂十四环-7,12-二烯烃)为前驱配体,1,10-邻菲啰啉为端接配体,高氯酸锰为金属核心,经回流反应合成了一个新型的异双核配合物［CuLMn(phen)₂］(ClO₄)₂·2CH₃OH(1),其结构和性能经UV-Vis, IR,元素分析,X-射线粉末衍射和X 射线单晶衍射表征。结果表明：1(CCDC: 1 445 582)属三斜晶系,空间群P-1,晶胞参数a=11.298(19) , b=15.17(4) , c=16.71(3) ,α=113.69(3), β=109.30(2), γ=93.08(4), V=2 417(9) ³, Z=2。 1在DMF中的最大吸收峰位于272 nm和361 nm。     

两个新型三核镍(Ⅱ)配合物的合成及其晶体结构

5-溴水杨醛和5-氯水杨醛分别与N-环己基-1,2-丙二胺经缩合反应制得Schiff碱配体(L1和L2); L1和L2分别与Ni(Ac)₂·4H₂O经配位反应合成两个新型的三核Schiff碱配合物(1和2),其结构经X-射线单晶衍射表征。1(CCDC: 1 008 203)和2(CCDC: 1 008 204)属单斜晶系,空间群P2₁/c,晶胞参数1：a=9.111(4) , b=12.089(6) , c=18.724(8) , β=92.117(7)°; 2： a=9.346 8(12) , b=11.507 3(15) , c=18.539(2) , β=93.774(2)°。     

Synthesis,Fluorescence and Dielectric Properties of Two Novel Compounds Based on Triethylenediamine Derivatives

Two compounds C_8H_(18)N_2Br_3Mn_(0.5)(1) and C_(12)H_(26)N_2Cl_4Mn(2) based on triethylenediamine derivatives were synthesized by solution method and were characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structure analysis, fluorescence test, circular dichroism(CD) analysis and dielectric measurement, respectively. According to single-crystal X-ray determination, compound 1 crystallizes in the cubic system, space group Pa3 with a = b = c = 13.7246(5) ?, Z = 24, V = 2585.2(3) ?~3; and compound 2 crystallizes in the orthorhombic system, space group P212121 with a = 7.9716(13), b = 15.309(3), c = 15.804(3) ?, Z = 4 and V = 1928.7(6) ?3. Fluorescent analysis of compound 1 showed an intense emission band at 670 nm when the exciting radiation was set at 378 nm and fluorescent analysis of compound 2 showed an intense emission band at 515 nm when the exciting radiation was set at 363 nm. Dielectric constants of compounds 1 and 2 were measured at different frequencies with temperature variation.