N-Methylation of ortho-substituted aromatic amines with methanol catalyzed by 2-arylbenzo[d]oxazole NHC-Ir(iii) complexes.

Seven new chelated cyclometalated Ir complexes of ABON,P, ABON,O, and ABON,C(carbene) based on a rigid and tunable 2-arylbenzo[d]oxazole backbone have been prepared for the N-methylation of amines. Among these three coordinated modes, ABON,C(carbene)-chelated iridium-based catalysts exhibited good performance in the monomethylation of aromatic amines with methanol (MeOH) as the green methylation reagent. The steric-modified synthesis of ABON,C(carbene) complexes was described. The most active ABON,C(carbene) complex with marginal steric hindrance as a catalyst was obtained from the benzoxazole ring without a substituent and methyl group of the benzimidazole ring on the N-heterocyclic carbene (NHC) ligand. A variety of amines including para- and meta-substituted aromatic amines, as well as heterocyclic amines, were formulated as suitable substrates. Importantly, this catalyst considerably promoted the yield of the N-methylation of ortho-substituted aromatic amines. Controlled kinetic experiments and deuterium-labeling reactions of these ortho-substituted amines were conducted under optimized conditions. On the basis of the experimental results, a plausible mechanism was proposed.

The Construction of C-N, C-O, and C(sp2)-C(sp3) Bonds from Fluorine-Substituted 2-Aryl Benzazoles for Direct Synthesis of N-, O-, C-Functionalized 2-Aryl Benzazole Derivatives.

Herein, a general and practical route to 2-(2-aminophenyl)- and 2-(2-alkoxyphenyl)-substituted benzazoles by nucleophilic aromatic substitution (SNAr) is described. Upon treatment with Cs2CO3, the formation of C-N, C-O bonds occur between fluorine-substituted 2-aryl benzazoles and a diverse range of nitrogen, oxygen nucleophiles to provide the targets in good to excellent yields. Commercially available nucleophiles and high atom economy are notable features of the protocol. Meanwhile, the construction of C(sp2)-C(sp3) bond was also furnished in the presence of palladium catalyst.

Amphiphilic Block Copolymers Directed Interface Coassembly to Construct Multifunctional Microspheres with Magnetic Core and Monolayer Mesoporous Aluminosilicate Shell.

Core-shell magnetic porous microspheres have wide applications in drug delivery, catalysis and bioseparation, and so on. However, it is great challenge to controllably synthesize magnetic porous microspheres with uniform well-aligned accessible large mesopores (>10 nm) which are highly desired for applications involving immobilization or adsorption of large guest molecules or nanoobjects. In this study, a facile and general amphiphilic block copolymer directed interfacial coassembly strategy is developed to synthesize core-shell magnetic mesoporous microspheres with a monolayer of mesoporous shell of different composition (FDUcs-17D), such as core-shell magnetic mesoporous aluminosilicate (CS-MMAS), silica (CS-MMS), and zirconia-silica (CS-MMZS), open and large pores by employing polystyrene-block-poly (4-vinylpyridine) (PS-b-P4VP) as an interface structure directing agent and aluminum acetylacetonate (Al(acac)3 ), zirconium acetylacetonate, and tetraethyl orthosilicate as shell precursors. The obtained CS-MMAS microspheres possess magnetic core, perpendicular mesopores (20-32 nm) in the shell, high surface area (244.7 m2 g-1 ), and abundant acid sites (0.44 mmol g-1 ), and as a result, they exhibit superior performance in removal of organophosphorus pesticides (fenthion) with a fast adsorption dynamics and high adsorption capacity. CS-MMAS microspheres loaded with Au nanoparticles (≈3.5 nm) behavior as a highly active heterogeneous nanocatalyst for N-alkylation reaction for producing N-phenylbenzylamine with a selectivity and yields of over 90% and good magnetic recyclability.

Simultaneous determination of 22 phthalate esters in polystyrene food-contact materials by ultra-performance convergence chromatography with tandem mass spectrometry.

A method for the determination of 22 phthalate esters in polystyrene food-contact materials has been established using ultraperformance convergence chromatography with tandem mass spectrometry. In this method, 22 phthalate esters were analyzed in <3.5 min on an ACQUITY Tours 1-AA column by gradient elution. The mobile phase, the compensation solvent, the flow rate of mobile phase, column temperature, and automatic back pressure regulator pressure were optimized, respectively. There was a good linearity of 20 phthalate esters with a range of 0.05-10 mg/L, diisodecyl phthalate and diisononyl phthalate were 0.25-10 mg/L, and the correlation coefficients of all phthalates were higher than 0.99 and those of 16 phthalates were higher than 0.999. The limits of detection and the limits of quantification of 15 phthalates were 0.02 and 0.05 mg/kg, meanwhile diallyl phthalate, diisobutyl phthalate, dimethyl phthalate, di-n-butyl phthalate, and di(2-ethylhexyl) phthalate were 0.05 and 0.10 mg/kg, and diisodecyl phthalate and diisononyl phthalate were 0.10 and 0.25 mg/kg. The spiked recoveries were in the range of 76.26-107.76%, and the relative standard deviations were in the range of 1.78-12.10%. Results support this method as an efficient alternative to apply for the simultaneous determination of 22 phthalate esters in common polystyrene food-contact materials.

Synthesis of o-Alkenylated 2-Arylbenzoxazoles via Rh-Catalyzed Oxidative Olefination of 2-Arylbenzoxazoles: Scope Investigation, Structural Features, and Mechanism Studies.

2-Arylbenzazoles are promising molecules for potential applications in medicine and material areas. Efficient protocols for direct regioselective functionalization of 2-arylbenzoxazoles are in high demand. Herein, we disclose a general method for selective ortho-olefination of 2-arylbenzo[d]oxazoles with alkenes enabled by versatile Cp*Rh(III) in high yields. This protocol features broad functional group tolerance and high regioselectivity. Intermolecular competition studies and kinetic isotope effect experiments imply that the oxidative olefination process occurs via an electrophilic C-H activation pathway. The molecular structure of the m-fluoro-substituted olefination product confirms regioselective C-H activation/olefination at the more hindered site in cases where the meta F atom or heteroatom substituent existed. Apparent torsion angles were observed in the structures of mono- and bis-olefination products, which resulted in distinct different chemical shifts of olefinic protons. Additionally, two gram-scale reactions and further transformation experiments demonstrate that this method is practical for synthesis of ortho-alkenylated 2-arylbenzoxazole derivatives.

Palladium, iridium and ruthenium complexes with acyclic imino-N-heterocyclic carbenes and their application in aqua-phase Suzuki-Miyaura cross-coupling reaction and transfer hydrogenation.

Palladium (4a­4c), iridium (5a­5c) and ruthenium (6a­6c) complexes have been prepared by in situ transmetalation from the corresponding silver complexes of acyclic imino-functionalized imidazolium chlorides [1-(Me)-imidazolium-3-{C(p-CH(3)-Ph)=N(Ar)}]Cl (3) (Ar = 2,4,6-trimethylphenyl (3a), 2,6-diisopropylphenyl (3b) and phenyl (3c)) with [Pd(COD)Cl(2)], [Cp*IrCl(2)](2) or [Ru(p-cymene)Cl(2)](2), respectively. Iridium and ruthenium complexes, 5a[PF(6)]­5c[PF(6)], 6a[PF(6)]­6c[PF(6)], 6c[BF(4)], 6c[BPh(4)] and 6c[NTf(2)], were obtained directly from 5a­5c and 6a­6c through an anion-exchange process with KPF(6), NaBF(4), NaBPh(4) and LiNTf(2) (bis(trifluoromethylsulfonyl)imide lithium), respectively. All complexes were characterized by FT-IR, (1)H and (13)C NMR spectroscopy and elemental analysis. Crystal structures of 4a, 5a and 6c[NTf(2)], and show that five-membered chelate ring is formed in these complexes by the coordination of the carbene carbon and the imino nitrogen atom, and the latter two are cationic compounds with Cl(-) and NTf(2)(-) as counteranion respectively. The catalytic performance of Pd complexes for Suzuki-Miyaura cross-coupling reactions in pure water and Ir and Ru complexes for transfer hydrogenation of ketones and imines was tested in a wide scope of substrates. Pd complex 4b with the largest steric hinder exhibited the best performance to gain moderate to excellent yields on catalyzing Suzuki-Miyaura cross-coupling of aryl chlorides and arylboronic acids in water. While in transfer hydrogenation of various ketones, all the Ir and Ru complexes were effective with good to excellent yields. Among all these complexes, 6c[PF(6)] was found most effective, and moderate yields could be obtained even in the transfer hydrogenation of imines. Moreover, different counteranions of Ru complexes are influential on catalyzing the transfer hydrogenation, with the sequence of PF(6)(-) ≈ BF(4)(-) > BPh(4)(-) > Cl(-) > NTf(2)(-).

Pd(OAc)2 catalyzed direct arylation of electron-deficient arenes without ligands or with monoprotected amino acid assistance.

An efficient arylation of electron-poor arenes has been developed without the addition of external ligands or in the presence of a catalytic monoprotected amino acid which assisted the reaction to proceed under mild conditions. The meta-selectivity was observed under both conditions.

Preparation of mononuclear, homodinuclear, and heterotrinuclear complexes by salicylaldiminato-functionalized imidazolium salt: approach to multifunctional catalysts.

A salicylaldiminato imidazolium salt that bears both a Schiff base and imidazolium salt moiety was used to synthesize heterometallic compounds that could serve as multifunctional catalysts in certain reactions. The successful preparation of seven mononuclear compounds with a variety of transition metals (Pd, Ir, Ru, Zn, Ni) illustrated the high versatility of this class of ligands, which is crucial for the design of catalysts. Synthesis of homodinuclear compounds and heterotrinuclear compounds provided practical methods to connect multiple metal fragments through these ligands. The heterotrinuclear complex (Ni/Ir) was employed as a catalyst in the reaction of dehalogenation/transfer hydrogenation of halo-acetophenones. The preliminary catalytic study showed that this heterometallic species is more active than a combination of the corresponding monometallic species.

Syntheses and structures of heterometallic clusters by the reaction of o-carboranyl cobaltadichalcogenolato complexes.

Metalladichalcogenolate cluster complexes [Cp'Co{E(2)C(2)(B(10)H(10))}]{Co2(CO)5} [Cp' = eta5-C5H5, E = S(3a), E = Se(3b); Cp' = eta5-C5(CH3)5, E = S(4a), E = Se(4b)], {CpCo[E(2)C(2)(B(10)H(10))]}(2)Mo(CO)2] [E = S(5a), Se(5b)], Cp*Co(micro2-CO)Mo(CO)(py)2[E(2)C(2)(B(10)H(10))] [E = S(6a), Se(6b)], Cp*Co[E(2)C(2)(B(10)H(10))]Mo(CO)2[E(2)C(2)(B(10)H(10))] [E = S(7a), Se(7b)], (Cp'Co[E(2)C(2)(B(10)H(10))]W(CO)2 [E(2)C(2)(B(10)H(10))] [Cp' = eta5-C5H5, E = S(8a), E = Se(8b); Cp' = eta5-C5(CH3)5, E = S(9a), E = Se(9b)], {CpCo[E(2)C(2)(B(10)H(10))]}(2)Ni [E = S(10a), Se(10b)] and 3,4-(PhCN(4)S)-3,1,2-[PhCN(4)SCo(Cp)S(2)]-3,1,2-CoC(2)B(9)H(8) 12 were synthesized by the reaction of [Cp'CoE(2)C(2)(B(10)H(10))] [Cp' = eta5-C5H5, E = S(1a), E = Se(1b); Cp' = eta5-C5(CH3)5, E = S(2a), E = Se(2b)] with Co2(CO)8, M(CO)3(py)3 (M = Mo, W), Ni(COD)2, [Rh(COD)Cl]2, and LiSCN4Ph respectively. Their spectrum analyses and crystal structures were investigated. In this series of multinuclear complexes, 3a,b and 4a,b contain a closed Co3 triangular geometry, while in complexes 5a-7b three different structures were obtained, the tungsten-cobalt mixed-metal complexes have only the binuclear structure, and the nickel-cobalt complexes were obtained in the trinuclear form. A novel structure was found in metallacarborane complex 12, with a B-S bond formed at the B(7) site. The molecular structures of 4a, 5a, 6a, 7b, 9a, 9b, 10a and 12 have been determined by X-ray crystallography.

Binuclear half-sandwich cobalt(III) and rhodium(III) ortho-carboranedichalocogenolato complexes with ether chain-bridged bis(cyclopentadienyl) ligand.

1, 1'-(3-Oxapentamethylene)dicyclopentadiene [O(CH(2)CH(2)C(5)H(5))(2)], containing a flexible chain-bridged group, was synthesized by the reaction of sodium cyclopentadienide with bis(2-chloroethyl) ether through a slightly modified literature procedure. Furthermore, the binuclear cobalt(III) complex O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(CO)I(2)](2) and insoluble polynuclear rhodium(III) complex {O[CH(2)CH(2)(eta(5)-C(5)H(4))RhI(2)](2)}(n) were obtained from reactions of with the corresponding metal fragments and they react easily with PPh(3) to give binuclear metal complexes, O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(PPh(3))I(2)](2) and O[CH(2)CH(2)(eta(5)-C(5)H(4))Rh(PPh(3))I(2)](2), respectively. Complexes react with bidentate dilithium dichalcogenolato ortho-carborane to give eight binuclear half-sandwich ortho-carboranedichalcogenolato cobalt(III) and rhodium(III) complexes O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(PPh(3))(E(2)C(2)B(10)H(10))](2) (E = S and Se), O[CH(2)CH(2)(eta(5)-C(5)H(4))](2)Co(2)(E(2)C(2)B(10)H(10)) (E = S and Se), O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(E(2)C(2)B(10)H(10))](2) (E = S and Se and O[CH(2)CH(2)(eta(5)-C(5)H(4))Rh(PPh(3))(E(2)C(2)B(10)H(10))](2) (E = S and Se). All complexes have been characterized by elemental analyses, NMR spectra ((1)H, (13)C, (31)P and (11)B NMR) and IR spectroscopy. The molecular structures were determined by X-ray diffractometry.

Synthesis and structure of heterometallic complexes (RhFe, CoFe) containing bridging 1,2-dicarba-closo-dodecarborane-1,2-dichalcogenolato ligands.

The prototype hetero-binuclear complexes containing metal-metal bonds, {CpRh[E2C2(B10H10)]}[Fe(CO)3] (Cp = Cp* = eta 5-Me5C5, E = S(5a), Se(5b); Cp = Cp = eta 5-1,3-tBu2C5H3, E = S(6a), Se(6b)) and {CpCo[E2C2(B10H10)]}[Fe(CO)3] (Cp = Cp* = eta 5-Me5C5, E = S(7a), Se(7b); Cp = Cp = eta 5-C5H5, E = S(8a), Se(8b)) were obtained from the reactions of 16-electron complexes CpRh[E2C2(B10H10)] (Cp = Cp*, E = S(1a), Se(1b); Cp = Cp, E = S(2a), Se(2b)), CpCo[E2C2(B10H10)] (Cp = Cp*, E = S(3a), Se(3b); Cp = Cp, E = S(4a), Se(4b)) with Fe(CO)5 in the presence of Me3NO. The molecular structures of {Cp*Rh[E2C2(B10H10)]}[Fe(CO)3] (E = S(5a), Se(5b)), {CpRh[S2C2(B10H10)]}[Fe(CO)3] (6a) {Cp*Co[S2C2(B10H10)]}[Fe(CO)3] (7a) and {CpCo[S2C2(B10H10)]}[Fe(CO)3] (8a) have been determined by X-ray crystallography. All these complexes were characterized by elemental analysis and IR and NMR spectra.

Di-mu-cyanato-bis[(cyanato-kappaN)(tetramethylethylenediamine-kappa2N,N')copper(II)] and catena-poly[[mu3-cyanato-kappa3O:N:N-bis[(cyanato-kappaN)(1,3-diaminopropane-kappa2N,N')copper(II)]]-mu3-cyanato-kappa3N:N:O].

The two title Cu(II) complexes, [Cu(2)(NCO)(4)(tmeda)(2)] (tmeda is tetramethylethylenediamine, C(6)H(16)N(2)), (I), and [Cu(NCO)(2)(pn)](n) (pn is 1,3-diaminopropane, C(3)H(10)N(2)), (II), have been synthesized and their crystal structures determined. In (I), which lies about an inversion centre, each Cu centre possesses a distorted tetragonal-pyramidal geometry with four basal N atoms from two cyanate anions [Cu-N = 1.945 (2) and 1.948 (3) A] and one tmeda molecule [Cu-N = 2.053 (2) and 2.071 (2) A], and one axial O atom [Cu-O = 2.737 (3) A] from another cyanate anion. The two neighbouring Cu atoms in (I) are joined by a pair of cyanates in an end-to-end fashion, forming a dimer. In (II), each Cu centre adopts a distorted square-bipyramidal geometry, with four equatorial N atoms from two cyanates [Cu-N = 1.988 (2) and 2.007 (3) A] and a pn ligand [Cu-N = 1.996 (3) and 2.011 (3) A], and one apical N atom [Cu-N = 2.437 (3) A] and an apical O atom [Cu-O = 2.900 (3) A] from two cyanates. In contrast with (I), the two neighbouring Cu atoms in (II) are bridged by two cyanates in an end-on fashion, to form a centrosymmetric dimeric unit. These units are further crosslinked, forming a two-dimensional network structure, via weak interactions between the bridging cyanate O atom and a neighbouring Cu atom, plus interactions of the amine H atoms with the cyanate O atoms and the terminal cyanate N atom.

Bis(dicyanamido)(diethylenetriamine-kappa(3)N)copper(II) and (dicyanamido)(triethylenetetramine-kappa(4)N)copper(II) dicyanamide.

Two new complexes, [Cu(C(2)N(3))(2)(dien)] (dien is diethylenetriamine, C(4)H(13)N(3)), (I), and [Cu(C(2)N(3))(trien)](C(2)N(3)) (trien is triethylenetetramine, C(6)H(18)N(4)), (II), have been characterized by single-crystal X-ray diffraction. Both complexes display a distorted tetragonal-pyramidal geometry. In (I), the Cu atom is coordinated in the basal plane by three diethylenetriamine N atoms [Cu-N = 2.000 (2), 2.004 (2) and 2.025 (2) A] and one terminal N atom [Cu-N = 1.974 (2) A] from one monodentate dicyanamide group, and in the apical position by one terminal N atom [Cu-N = 2.280 (2) A] from the other monodentate dicyanamide group. In (II), the Cu atom is surrounded by four triethylenetetramine N atoms [Cu-N = 2.012 (2), 2.014 (2), 2.019 (2) and 2.031 (2) A in the basal plane] and a terminal N atom [Cu-N = 2.130 (2) A in the apical site] from one monodentate dicyanamide group. The other dicyanamide anion is not directly coordinated to the metal atom. In both (I) and (II), hydrogen-bond interactions between the uncoordinated terminal N atoms of two dicyanamide ions and the amine H atoms lead to the formation of three-dimensional networks.