Asymmetric Michael Reaction of Malononitrile Catalyzed by Chiral Ru(Ⅱ) Complex and Achiral Base

Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ～3] We achieved catalytic enantioselective Michael addition reactions of malononitrile with chiral vicinal diamine-Ru(Ⅱ) complex in the presence of achiral base. High yields and moderate ee were observed.     

DNA Interaction and Cytotoxic Activity of a Chiral Amino-alcohol Schiff Base Derived Cu(Ⅱ) Complex

A novel copper(Ⅱ) complex based on chiral amino-alcohol derived Schiff base ligand,[Cu_4(R-L)_4(H_2O)_2]·(CH_3COOH)_2·(H_2O)(1,(R)-H_2 L =(R)-3-phenyl-2-(2-hydroxy-3-methoxybenzylideneamino) propane-1-ol),was synthesized and characterized by EA,IR,UV-Vis,ESI-MS,circular dichroism spectra and single-crystal X-ray diffraction.Complex 1 crystallizes in orthorhombic,space group Ρ2_12_12 with a = 15.7660(14),b = 49.526(3),c = 10.4213(9) ?,V = 8137.2(12) ?~3,Ζ = 4,C_(72)H_(81)Cu_4N_4O_(19),Mr = 1560.57,μ = 1.096 mm~(-1),F(000) = 3244,Flack = 0.06(3),the final R = 0.0924 and w R = 0.2451(I 2σ(I)) for 41108 observed reflections.The interactions of the complex with calf thymus DNA(CT-DNA) were investigated by some spectroscopic technique methods.The results show the complex exhibits strong binding with CT-DNA.In addition,in vitro cytotoxicity test of 1 towards four kinds of human cancerous cell lines(He La,HL-60,Caco-2 and A549) showed substantial cytotoxic activity.The experimental investigations indicated that the chirality of complex 1 play an important role in cytotoxicity and interactions with DNA.     

Synthesis and Crystal Structure of a Chiral Manganese(Ⅲ) Schiff Base Complex

A chiral salency complex,[Mn(Salency)(H2O)2](PF6)·2H2O 1(Salency =(R,R)-N,N'-bis(salicylidene)-1,2-cyclohexanediamine),has been prepared by the reaction of Mn(CH3COO)3·2H2O with Salency and NH4PF6,and was established by X-ray diffraction techniques.The complex crystallizes in triclinic,space group P1 with a=9.299(8),b=10.012(8),c=13.461(11),α=92.037(15),β=92.974(12),γ=93.530(18)°,V=1248.3(18)3,C20H28F6MnN2O6P,Mr = 592.35,Z=2,Dc=1.038 g/cm3,F(000)=608,μ=0.676 mm-1,the final R=0.0651 and wR=0.1880 for 5260 observed reflections with I 2σ(I).     

Catalytic Asymmetric Cyclopropanation using a New Chiral β-Diketone Cu (Ⅱ) Complex as a Catalyst

ManytransitionmetalcomPlexescatalyzethedecomPositionofa-diazoesterbythemethylenetransferreactiontoolefins,givingthecorrespondingcyclopropaneadductsl'z.Thismethodhasbeenwidelyusedinthesynthesisofnaturalproducts.Sofar,variouskindsoftransitionmetalcomPlexeshavebeenusedintheasymmetriccyclopropanation"'.6-diketonecomplexessuchasCu(acac)2(acac=acetylacetone)areamongthemostpopuIarcatalystsforthecyclopropanationofalkeneswithdiazocomPounds,butthefirstchiralo-diketonecomplexwasreportedonlyinl9845.Wesy…     

Complex Pd( Ⅱ ) with Vinyiphosphine and Its Application in Sonograshira Cross Coupling Reaction

合成了含有大位阻和富电子膦配体的1,2-二苯基乙烯基膦配体,并研究了以1,2-二苯基乙烯基膦配体和二氯化二苯腈合钯(Ⅱ)为催化剂催化的Sonograshira交叉偶联反应.     

Asymmetric Borohydride Reduction of Acetophenone Catalyzed by Chiral Salen-Co(Ⅱ) Complex Using Sodium Borohydride

Development of efficient catalytic asymmetric reactions is the most challenging task in current synthetic chemistry; much effort has been devoted to create the chiral metal complexes of asymmetric catalysis. In the last two decades' many brand-new ligands had been synthesized and their combination with various metal ions has been applied in asymmetric catalysis. However, most ligands have only narrow applications and their use is limited to some reactions. Exceptionally, a few ligands and their metal complexes such as binaphthol, semicollin,and binap show wide applicability. Chiral salen ligand is one of such ligands and their metal complexes are now used as the catalysts for a variety of asymmetric reactions such as epoxidation^[1], aziridination^[2], cyclopropanation^[3], Diels-Alder reaction^[4], asymmetric transfer hydrogenation of aromatic ketones^[5] and kinetic resolution of racemic epoxides^[6] and so on.     

Structure of a Polymeric Mn(Ⅱ) Complex Bridged by Benzenetetracarboxylate

The single crystals of the title compound were obtained from a reaction of MnCO3,benzenetetracarboxylic acid (H4BTC)and imidazole in an aqueous solution.The crystal of Mn(II)complex (C28H34Mn2N12O12(4H2O,Mr=912.62) belongs to tricli nic,space group Pī with a=10.036(1),b=10.650(1),c=11.102(1)A,α=114.72(2),β=95.75(1),γ=108.46(2)°,V=984.2(2)A3,Z=1,Dc=1.540 g/cm3,F(000)=472,μ(MoKα)=0.726 mm-1,R=0.0409 and wR=0.1166 for 3909 observed reflections (I>2σ(I)).The crystal consists of the polymeric Mn(II)complex anions and discrete Mn(II) complex cations,both with normal octahedral coordination geometry.Each BTC bridges two Mn(II) atoms to form the anionic polymeric chain,and the cations distribute be-tween the chains and link them through both classic and weak C-H…O H-bonding.     

Asymmetric Hydroformylation of Olefins Catalyzed by a Chiral Diphosphite-Rhodium Complex

A C2-symmetrical aryl diphosphite derived from chiral binaphthol was prepared and its rhodium complex was used as catalysts in the asymmetric hydroformylation of olefins. High catalytic activity and good regioselectivity were observed. Up to 31.2% ee and 38.1% ee were achieved for the hydroformylation of 4-fluoro-styrene and vinyl acetate respectively. The influences of ligand-to-metal ratio, reaction temperature and the pressure of syn-gas on the enantioselectivity and regioselectivity were also studied.     

Chiral Resolution of β-dl-Phenylalanine Using Chiral Macrocyclic Nickel(Ⅱ) Complexes

The reactions of chiral four-coordinated nickel(Ⅱ) complex [Ni(RR-L)](ClO4)2/[Ni(SS- L)](ClO4)2 with β-dl-phenylalanine in acetonitrile/water gave a six-coordinated enantiomer of [Ni(RR-L)(β-d-HPhe)](ClO4)2(1) and [Ni(SS-L)(β-l-HPhe)](ClO4)2(2), respectively(L = 5,5,7, 12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, HPhe = phenylalanine). Single-crystal X-ray diffraction analyses revealed that the nickel(Ⅱ) atom displays a distorted octahedral coordination geometry by coordinating with four nitrogen atoms of L in a folded configuration, and two carboxylate oxygen atoms of β-d/l-HPhe in cis-position in both complexes. The monomers of [Ni(RR-L)(β-d-HPhe)]2+ and [Ni(SS-L)(β-l-HPhe)]2+ are connected through intermolecular hydrogen bonds to generate one-dimensional zigzag chains, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy.     

Formation of a Stable Cationic Hydridodimethylplatinum(IV) Complex by the Reaction of Bis(μ-dimethyl sulfido)tetramethyldiplatinum(II) with Protonated 1,4,7-Triisopropyl-1,4,7-triazacyclononane. A First Example of Oxidative N-H Addition to a Platinum(II) Complex

The complex bis(-dimethyl sulfido)tetramethyldiplatinum(II) reacts with 1,4,7-triisopropyl-1,4,7-triazacyclopropanone (L) over the course of 24 h at room temperature in THF-d ₈ to give [PtMe₂(L)] and PtMe₂(SMe₂)₂. Subsequent addition of 1 mol of trifluoromethanesulfonic acid results in immediate formation of a previously unknown stable cationic complex [PtMe₂H(L)]⁺SO₃CF₃ ^-. This product can also be prepared by oxidative addition of the N-H bond of LH⁺SO₃CF₃ ^- to the starting complex, which points to a higher basicity of the platinum atom in [PtMe₂(L)] compared with the nitrogen atom in the ligand L. The pK _a of the cationic hydride of platinum(IV) was estimated.     

Chiral Brønsted Acid from Chiral Phosphoric Acid Boron Complex and Water: Asymmetric Reduction of Indoles

A new chiral Brønsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This “designer acid catalyst”, which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3-protonation and hydride-transfer processes. Besides, bulky C2-alkyl-substituted N-unprotected indoles are also suitable for this system.     

Synthesis and Crystal Structure of a Novel Terpyridine-based Cd(Ⅱ) Complex

A novel terpyridine-based complex CdL'S2 (L'= oxide of L; L = 10-hexyl-3-(2,6-di(pyridine-2-yl)pyridine-4-yl)-10H-phenothiazine) has been solvothermally synthesized and characterized by FT-IR spectroscopy, elemental analysis, 1 H NMR and X-ray crystallography. The sulfur of phenothiazine moiety was oxidized when the crystal is formed. The complex C36H37CdN5O2S3 crystallizes in triclinic, space group P1 with a = 9.4452(9), b = 13.0181(14), c = 14.6721(18), α = 73.872(1), β = 81.531(1), γ = 87.547(2)°, V = 1714.2(3)3 , Mr = 780.29, Dc = 1.512 g·cm-3 , μ = 0.861 mm-1 , F(000) = 800, Z = 2, the final R = 0.0456 and wR = 0.1059 for Ⅰ > 2σ(Ⅰ). The Cd(Ⅱ) is coordinated by two terminal sulfur ions and three pyridyl nitrogen atoms in a distorted trigonal bipyramidal geometry. Universal hydrogen bonds between the neighboring molecules have generated a supramolecular arrangement which contributes to the stability of the title complex. Fluorescence property and thermogravimetry of the complex have also been investigated and discussed.     

Activation of Nitromethane to Cyanide by a Mononuclear Cu(Ⅱ) Complex

The tridentate ligand DPA-Me(2) was readily prepared from DPA(DPA = 2,2-dipicolylamine) in high yield. The mixture of 2 and Cu(Cl O4)26H2O in methanol gave a five-coordinated mononuclear complex [(DPA-Me)Cu(Me CN)(Cl O4)](Cl O4)(3). Recrystallization of 3 in CH3NO2 led to an activation of CH3NO2 to CN- by the formation of product as a dinuclear cyanide bridged complex {[Cu(DPA-Me)]2(CN)(Cl O4)3CH3NO2}n(4). Both 3 and 4 were characterized by X-ray crystallography, IR spectroscopy and elemental analysis. The crystal of 4 was grown in space group P21/c with a = 17.74582(15), b = 13.89877(11), c = 14.92546(13) , β = 91.4246(8)°, V = 3680.15(5) 3, Z = 4, Dc = 1.695 g/cm3, F(000) = 1912, C28H33Cl3Cu2N8O14, Mr = 939.05, μ = 1.602 cm-1, Cu Kα radiation(λ = 1.54184 ), R = 0.0485 and w R = 0.1246 for 6414 observed reflections with I 2σ(I).     

Crystal Structure of a Nickel(Ⅱ) Complex with Asymmetric L-Histidine Ligand

A novel nickel(Ⅱ) complex with L-histidine has been synthesized and solved by single-crystal X-ray diffraction analysis at physiological pH. The title complex (C7H16NiN4O6S, Mr= 343.01) crystallizes in monoclinic, space group P21 with a = 7.2194(7), b = 7.5968(7), c =12.2797(11) (A), β = 93.3110(10)°, V = 672.35(11) (A)3, Z = 2, Dc= 1.694 g/cm3, F(000) = 356,μ(MoKα) = 1.626 mm-1, T = 293(2) K, the final R = 0.0184 and wR = 0.0426 for 2207 observed reflections with I ＞ 2σ(Ⅰ). The complex provides insights into a possible structural arrangement between nickel (Ⅱ) and L-histidine which may be physiologically important and abundantly present in biological systems.     

Synthesis,Electrochemical and Fluorescent Properties of a New Zinc(Ⅱ) Complex through Self-assembly Reaction of 2,2'-Bipyridine-3,3'-dicarboxylic Acid

A new Zn(Ⅱ) complex [Zn(Phen)_2(C_(12)H_6O_4N_2)(H_2O)]·3H_2O with 2,2?-bipyridine-3,3?-dicarboxylic acid and 1,10-phenanthroline(Phen) as ligands was synthesized, and the crystal data are as follows: monoclinic, space group P2_(1/n), a=12.5581(11), b=17.3382(17), c=15.6687(14) ?, β=110.579(2)o, M_r=731.02, V=3193.9(5) ?~3, Dc=1.520 g/cm~3, Z=4, μ(Mo Kα)=0.833 mm~(-1), F(000)=1508, the final R=0.0431 and w R=0.0936. In the title complex, the central Zn(Ⅱ) ion is located in a distorted octahedral coordination environment. The electrochemical and fluorescent properties were studied. The title complex possesses irreversible electron transfer in the electrode reaction, and it has a strong emission peak in the range of 470~505 nm, with the excitation wavelength being 488 nm.     

Asymmetric Cyclopropanation Catalyzed by Four Stereoisomers of a Copper-(Schiff-base) Complex with Double Chiral Centers

Catalytic asymmetric cyclopropanation of diazoacetates with olefins has attracted much attention. Those catalysts containing various metals and optically active ligands have been employed for this reaction1,2. The first catalytic asymmetric cyclopropanation reaction was reported in 1966 by Nozaki et al.3. The author used the copper(II) complex 1 bearing a salicyladimine ligand as catalyst though with a low e.e. value of 6%. Aratani and his coworkers designed the copper-(Schiff-base) comp…     

Synthesis and Crystal Structure of a New Dinuclear Manganese(Ⅱ) Manganese(Ⅲ) Complex of a Macrocyclic Ligand

A mixed-valence dinuclear manganese complex, [MnⅡMnⅢL](ClO4)·1/2MeOH, where L is a macrocyclic ligand derived from the cyclocondensation of sodium 2,6-diformyl-4-methylphenolate with N,N-bis(2-aminoethyl)-2-hydroxybenzyl amine, was obtained and its structure was determined by X-ray diffraction. The orange crystal is a monoclinic system with space group P21/c and lattice parameters a=1.1617(4), b=1.4005(3), c=1.4641(3) nm, β=113.03(2)°, and Z=2. The crystal structure shows that each pendant-arm is bonded in a bidentate fashion to the adjacent metal atom and that both the arms are on the same side of the macrocycle. The two Mn atoms are bridged by two μ2-phenoxy oxygen atoms of the tetra-imine macrocycle, and each Mn atom, locating in a trigonal prismatic coordination environment(N3O3), is six-coordinated by the two imine nitrogen atoms, one tertiary nitrogen atom and a pendant phenol moiety apart from the two oxygen atoms.     

First Magnesium-mediated Carbonyl Benzylation in Water

Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones.     

Trihydrated Complex of Tetrabenzimidazole Copper(Ⅱ) Sulfate

A Trihydrated complex of benzimidazole copper(Ⅱ) sulfate [(C7H6N2)4CuSO4]·3H2O was synthesized and structurally characterized. The crystal structure of this compound is built up of six solvated water molecules and two dissimilar copper ions identified as Cu1 and Cu2. The coordination geometry of copper(Ⅱ) is a slightly distorted square pyramid. The four equivalent tertiary nitrogen atoms of the benzimidazole ligand form an equatorial plane, while the oxygen atoms of sulfato occupy the axial site. In the solid state, the title compound forms a three dimensional network structure via hydrogen bonds. The benzimidazole, sulfato ion and H2O moieties are connected by the intermolecular hydrogen bonds. The (EPR) spectrum shows axial symmetry with g⊥=2.039 and g∥=2.285. Variable temperature magnetic susceptibility shows that there is a weak antiferromagnetic interaction between the neighboring copper(Ⅱ) ions.     

Investigation of Enantiomeric Separation of Chiral Drugs by CE Using Cu(II)�CClindamycin Complex as a Novel Chiral Selector

The enantiomeric separation of several basic drugs was investigated using copper(II)?Cclindamycin as a new chiral selector. The results show that the chiral selector allows high-resolution separation of some racemic basic drugs, including tropicamide, propranolol, sotalol, bisoprolol, epinephrine, esmolol, atenolol, and metoprolol. The enantioselectivity was influenced by parameters such as the type of metal ion, ratio of clindamycin and Cu(II), pH of the background electrolyte, clindamycin concentration, applied voltage, and capillary temperature. The optimal separation conditions were determined to be 20 mM clindamycin/10 mM Cu²⁺, pH 9.06, at 20 kV and 22 °C within 25 min.