Synthesis of 3-pyrrol-3′-yloxindoles with a carbamate function

By the reaction of methyl {4(3)-[2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)acetyl]phenyl} carbamates with ethyl 3-aminocrotonate at boiling in the mixture toluene-anhydrous ethanol, 2: 1, ethyl 5-{3(4)-[(methoxycarbonyl)amino]phenyl}-2-methyl-4-(2-oxo-2,3-dihydro-1H-indol-3-yl)-1H-pyrrole-3-carboxylates were obtained. The condensation of methyl {3(4)-[2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)acetyl] phenyl}carbamates with ethyl acetoacetate in the presence of ammonium acetate and 20 mol% of 1-methyl-3-butylimidazolium chloride or 1-methyl-3-octylimidazolium tetrafluoroborate at boiling in anhydrous ethanol led to the formation of the corresponding 3-pyrrol-3′-yloxindoles with a carbamate function.     

Synthesis and Crystal Structure of a 3-Arylamino-3-Deoxy Sugar Derivative

1INTRODUCTION Amino sugars in which a hydroxyl group of a mo-nosaccharide is replaced by an amino group play a wide variety of important biological roles[1]and have broad applications in chemical,biochemical,medi-cinal,and pharmaceutical fields[2,3].Amino sugars are chiral synthon of azasugar and polyose,many of which are found to be potential chemotherapeutic agents for the treatment of diseases,such as diabetes and cancer,inflammation and viral infections,inclu-ding HIV[4].Particularly…     

1,3-Dipolar cycloaddition between a metal-azide (Ph3PAuN3) and a metal-acetylide (Ph3PAuC≡CPh): an inorganic version of a click reaction

This report describes the synthesis and characterization of 1,5-bis-triphenylphosphinegold(I) 1,2,3-triazolate (3((1,5))). The synthesis of the dinuclear complex 3((1,5)) is achieved via an unprecedented inorganic click (iClick) reaction between the metal-azide PPh(3)AuN(3) (1) and the metal-acetylide PPh(3)Au-C≡CPh (2). Characterization of 3((1,5)) includes multinuclear NMR spectroscopy, combustion analysis, and single crystal X-ray crystallography. Experimental characterization is complemented with density-functional-theory (DFT) calculations which indicate the 1,4-isomer 3((1,4)) is less stable by 3.3 kcal mol(-1). The energetic difference lies primarily in the ability of the phenyl group in the 4-position of 3((1,5)) to lie coplanar with the triazolate to create a delocalized π-bonding HOMO orbital.     

Why are a 3 ions rarely observed?

It has been determined experimentally that a(3) ions are generally not observed in the tandem mass spectroscopic (MS/MS) spectra of b(3) ions. This is in contrast to other b(n) ions, which often have the corresponding a(n) ion as the base peak in their MS/MS spectra. Although this might suggest a different structure for b(3) ions compared to that of other b(n) ions, theoretical calculations indicate the conventional oxazolone structure to be the lowest energy structure for the b(3) ion of AAAAR, as it is for other b(n) ions of this peptide. However, it has been determined theoretically that the a(3) ion is lower in energy than other a(n) ions, relative to the corresponding b ions. Furthermore, the a(3) --> b(2) transition structure (TS) is lower in energy than other a(n) --> b(n-1) TSs of AAAAR, compared with the corresponding b ions. Consequently, it is suggested that the b(3) ion does fragment to the a(3) ion, but that the a(3) ion then immediately fragments (to b(2) and a(3)) because of the excess internal energy arising from its relatively low energy and the facile a(3) --> b(2) reaction. That is why a(3) ions are not observed in the MS/MS spectra of b(3) ions.     

[Cu3(dppm)3(μ 3-I)2][(0.5TCNQ)], a radical salt derived from a donor with a copper(I) trimer

A radical salt 1, [Cu₃(dppm)₃(μ ₃-I)₂][(0.5TCNQ)], has been prepared by reaction of CuI, dppm (diphenylphosphinomethane) and TCNQ (7,7′,8,8′-tetracyanoquinodimethane) with a molar ratio of 1 : 1 : 0.5 and characterized by IR, UV–Vis and solid-emission spectroscopy. Its structure was determined by X-ray crystallography. 1 also has photoluminescence (λ _max = 653 nm) at room temperature. Magnetic properties indicate that TCNQ is in the reduced state (TCNQ^2?).     

Template-free Synthesis of a Novel 3D Cage-like Nanostructured α-Fe2O3

Synthesis of inorganic nanostructures with specific size and well defined morphologies has attracted considerable attention due to their superior electrical, optical, magnetic, and chemical properties[1―6]. Up to now, various kinds of metal oxide[7], sulfide[8], and hydrate[9] with controlled hierarchical and complex morphologies have been successfully synthesized.     

Desorption Behaviour of HF,HCFC-133a and HFC-134a on a Catalyst Supported on γ-AlF3

The desorption behaviour (desorption temperature and extent of desorption) of HF,HCFC-133a (CF₃CH₂Cl) and HFC-134a (CF₃CH₂F) on γ-AlF₃ or catalyst supported on γ-AlF₃ was studied using an adsorption apparatus and TG, DTA and DSC methods. On the basis of the results a reaction mechanism was proposed for the preparation of HFC-134a. The γ-AlF₃ employed for preparing the catalyst was expected to be stable below 550°C based on the crystalline phase transition temperature of γ-AlF₃. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Crystal Structure of a Rubidium Lanthanum Borate Rb3La3（BO3）4

The title compound was obtained by the flux method and its structure was determined. It crystallizes in monoclinic, space group P2/c with a = 11.0024（17）, b = 9.2979（14）, c = 14.500（2） A, β = 110.879（2）°, V = 1385.9（4） A^3, Z = 4, Mr= 908.38, F（000） = 1592, p = 19.601 mm^-1, Dc = 4.353 g/cm^3, the final R = 0.0481 and wR = 0.1257 for 2532 observed reflections with I 〉 2σ（I）, The Rb3La3（BO3）4 structure can be viewed as a 3-dimensional scaffold-like framework constructed by La-O polyhedra and BO3 groups. Two Rb＋ ions locate in a channel along the a direction and the rest one in a cavity.     

Synthesis,structure, magnetic properties and kinetics of formation of a cluster containing a {Cu3(μ3-OH)} core supported by a triazole-based ligand

The trinuclear copper complex, [Cu₃(μ₃-OH)(CTMB)₃(NO₃)₂(CH₃CN)₂]·5CH₃CN·H₂O (1) {CTMB = cyclohexotriazole-3-(4-methoxybenzamide)}, has been prepared by mixing Cu(NO₃)₂·2.5H₂O and CHMBH {CHMBH = N,N′-cyclohexane-1,2-diylidene-bis(4-methoxybenzoylhydrazide)} in acetonitrile under ambient conditions. Compound 1 was characterized by IR and UV–visible spectroscopies as well as elemental analyses. X-ray crystallography shows that the cluster contains a {Cu₃(μ₃-OH)} core supported by three triazole-based Schiff base ligands. Each Cu is bound to the 2-N of one triazole ring and the 1-N of another. However, the coordination sphere of each Cu is different, one is five-coordinate and the other two are six-coordinate and bridged by a NO₃ group. The six-coordinate sites are different, one has a terminal NO₃ and the other a MeCN ligand. Magnetic measurements revealed the presence of isotropic and antisymmetric exchange between the copper(II) centers. The data were analyzed using the Hamiltonian containing isotropic exchange for an isosceles triangle together with antisymmetric exchange: H = –J₁(S₁S₂ + S₂S₃)?J₂S₁S₃ + G[S₁ × S₂ + S₂ × S₃ + S₃ × S₁]. Compound 1 exhibits strong antiferromagnetic coupling with J₁ = ?180 and J₂ = ?118 cm^?1 and antisymmetric exchange with G_z = 15 cm^?1. Stopped flow spectrophotometric studies show that the formation of 1 occurs in three distinct phases and the kinetics of each phase has been determined.     

Oxidative group transfer to a triiron complex to form a nucleophilic μ(3)-nitride, [Fe3(μ(3)-N)]-

Utilizing a hexadentate ligand platform, a high-spin trinuclear iron complex of the type ((tbs)L)Fe(3)(thf) was synthesized and characterized ([(tbs)L](6-) = [1,3,5-C(6)H(9)(NPh-o-NSi(t)BuMe(2))(3)](6-)). The silyl-amide groups only permit ligation of one solvent molecule to the tri-iron core, resulting in an asymmetric core wherein each iron ion exhibits a distinct local coordination environment. The triiron complex ((tbs)L)Fe(3)(thf) rapidly consumes inorganic azide ([N(3)]NBu(4)) to afford an anionic, trinuclear nitride complex [((tbs)L)Fe(3)(μ(3)-N)]NBu(4). The nearly C(3)-symmetric complex exhibits a highly pyramidalized nitride ligand that resides 1.205(3) ? above the mean triiron plane with short Fe-N (1.871(3) ?) distances and Fe-Fe separation (2.480(1) ?). The nucleophilic nitride can be readily alkylated via reaction with methyl iodide to afford the neutral, trinuclear methylimide complex ((tbs)L)Fe(3)(μ(3)-NCH(3)). Alkylation of the nitride maintains the approximate C(3)-symmetry in the imide complex, where the imide ligand resides 1.265(9) ? above the mean triiron plane featuring lengthened Fe-N(imide) bond distances (1.892(3) ?) with nearly equal Fe-Fe separation (2.483(1) ?).     

Synthesis of LiNbO_3 via a hydrothermal route and characterization

Lithium niobate (LiNbO3) crystal, used in many optical fields, has been of great interest for fundamental science and applications in optics for many years due to its excellent ferroelectric properties such as piezoelectricity, pyroelectrical, electro-optical, photorefractive and nonlinear-optical properties. Several methods for synthesizing lithium niobate crystal have been reported, for instance Czochralski growth, top seeded solution growth (TSSG), liquid phase epitaxy, laser deposition, …     

From a localized H3O radical to a delocalized H3O+···e- solvent-separated pair by sequential hydration

The impact of microhydration on the electronic structure and reactivity of the H(3)O moiety is investigated by ab initio calculations. In the gas phase, H(3)O is a radical with spin density localized on its hydrogen end, which is only kinetically stable and readily decomposes into a water molecule and a hydrogen atom. When solvated by a single water molecule, H(3)O preserves to a large extent its radical character, however, two water molecules are already capable to shift most of the spin density to the solvent. With three solvating water molecules this shift is practically completed and the system is best described as a solvent-separated pair of a hydronium cation and a hydrated electron. The electronic structure of this system and its proton transfer reactivity leading to formation of a hydrogen atom already resemble those of a proton-electron pair in bulk water.     

The predissociation of Li2 b3Πu by a3Σ+u

⁶Li₂ 1³Δ_g(F₁) → b³Π_u(F₁v = 0–11) rotationally resolved fluorescence spectra are recorded following perturbation-facilitated optical—optical double resonance excitation of 1³Δ_g via spin—orbit mixed A¹Σ⁺_u ∼ b³Π_u(F₁e) intermediate levels. The f-symmetry Λ-components of b³Π_u(F₁) are broadened above the 0.05 cm⁻¹ detection threshold owing to predissociation by the vibrational continuum of the a³Σ⁺_u state. The observed v = 0–11, N = 31f level widths were used to determine the potential energy curve for the Li₂ a³Σ⁺_u state in the region 2.35 < R < 2.60 Å and 11200 < E < 14900 cm⁻¹ (relative to E = 0 at the minimum of X¹Σ⁺_g). The a³Σ⁺_u ∼ b³Π_u curve crossing is at R = 2.57 Å and E = 11246 cm⁻¹ and the electronic part of the − BN·LL-uncoupling matrix element is 〈b Π¦L⁺ ¦aΣ〉 = 1.216H at an R-centroid Rv_bϵ_a = 2.61Å.     

Radical reaction HCNO + 3NH: a mechanistic study

The complex triplet potential energy surface for the reaction of HCNO with NH is investigated at the G3B3 level using the B3LYP/6-311++G(d,p), and QCISD/6-311++G(d,p) geometries. Various possible isomerization and dissociation pathways are probed. The initial association between HCNO and NH is found to be carbon to nitrogen attack leading to HNCHNO 2a, which can convert to 2b, 2c, and 2d. Subsequently, 1,4-H-shift of 2a to form NCHNOH 3a followed by dissociation to P ₂ (¹HCN + ³HON) is the most feasible pathway. Much less competitively, 2d undergoes successive 1,3-H-shift and C-N cleavage to form HNCNOH 8b, and then to product P ₃ (¹HNC + ³HON), the second feasible pathway. 8b can alternatively isomerize to 8c followed by N–O bond rupture to generate P ₆ (²OH + ²HNCN), the lesser followed feasible pathway. In addition, 2b takes continuously 1,3- and 1,2-H-shift to form NC(H)NHO 6a, then to ONHCNH 7a which can convert to 7b. Eventually, 7b may take C-N bond fission to produce P ₅ (¹HNC + ³HNO), the least feasible pathway. The present paper may be helpful for future experimental identification of the product distributions for the title reaction, and may be helpful to deeply understand the mechanism of the title reaction.     

Synthesis,Crystal Structure and Catalytic Properties of a Novel Ni(Ⅱ) MOF with a Rare [3+3+3] Nine Fold Interpenetrated Network

Metal-organic frameworks are a sort of rapid development crystal solids, which have greatly attracted a large amount of attention in recent decades. The construction of 3D [Ni(bcp)(bpp)]_n(namely complex 1) displays a rare [3+3+3] nine-fold interpenetrated diamond topology, which can be successfully synthesized by a mixed strategy of 1,3-bis(4-carboxyphenoxy) propane(H_2bcp) and 1,4-bis(4-pyridylmethyl) piperazine(bpp). The interpenetrated network may be ascribed to these flexible bridging linkers to facilitate the penetration degree. In addition, the resultant sample was adequately characterized by elemental analysis, single-crystal X-ray diffraction, powder X-ray diffraction, and thermal gravimetric analysis. Furthermore, the as-synthesized sample can be used as catalysis for chemical fixation of CO_2 and epoxide to carbonate.     

1,3-Dipolar cycloaddition of alkenes to 3’-azido-3’-deoxythymidine as a route to 3’-deoxythymidin-3’-yl derivatives

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Assessment of the absolute configuration of a series of (3R)-3-hydroxy-3-alkyl-β-lactams

The absolute stereochemistry of a series of (3R)-3-hydroxy-3-alkyl-β-lactams has been determined by circular dichroism and NMR spectroscopies. The sign of the circular dichroism band between 250 and 220 nm was related to the stereochemistry by applying the β-lactam sector rule. The NMR analysis unambiguously determines the relative configuration at C3 and C4 of the β-lactam ring. The reliability of the method has been proved by X-ray analysis of two of the examined compounds. The obtained results are in agreement with the mechanism proposed for the employed synthetic route.     

Structure and Properties of a New Rare-earth Borate LiSrY_2（BO_3）_3

The structure of LiSrY2(BO3)3 has been solved by single-crystal X-ray diffraction analysis at 298 and 113 K on different diffractometers.It crystallizes in trigonal with space group P-3m1(No.164).The cell parameters at room temperature are as follows:a = 10.3345(9),c = 6.4049(11) ,V = 592.41(13) 3,Z = 3,Mr = 448.81,F(000) = 618,μ = 21.327 mm-1 and Dc = 3.774 g/cm3.The crystal structure consists of gear-like [BY6O33] groups which are linked together by corner-sharing to form a two-dimensional layer parallel to the ab plane.These layers are connected one after another by sharing oxygen atoms with B(2) atoms along the c direction to construct a three-dimensional framework.Li and Sr atoms just occupy the cavities formed by oxygen atoms.In addition,the vibrational spectroscopy of LiSrY2(BO3)3 and photoluminescence properties of the Eu3+ doped LiSrY2(BO3)3 were also studied.