Enantioselective transfer hydrogenation of pro-chiral ketones catalyzed by novel ruthenium and iridium complexes of well-designed phosphinite ligand

Abstract

The interaction of [Ru(η⁶-arene)(μ-Cl)Cl]₂ and Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ with a new Ionic Liquid-based phosphinite ligand, [(Ph₂PO)-C₆H₉N₂Ph]Cl, (2) gave [Ru((Ph₂PO)-C₆H₉N₂Ph)(η⁶-p-cymene)Cl₂]Cl (3), [Ru((Ph₂PO)-C₆H₉N₂Ph)(benzene)Cl₂]Cl (4) and [Ir((Ph₂PO)-C₆H₉N₂Ph)(C₅Me₅)Cl₂]Cl (5), complexes. All the compounds were characterized by a combination of multinuclear NMR and IR spectroscopy as well as elemental analysis. Furthermore, the Ru(II) and Ir(III) catalysts were applied to asymmetric transfer hydrogenation of acetophenone derivatives using 2-propanol as a hydrogen source. The results showed that the corresponding alcohols could be obtained with good activity (up to 55% ee and 99% conversion) under mild conditions. Notably, [Ir((Ph₂PO)-C₆H₉N₂Ph)(C₅Me₅)Cl₂]Cl (5) is more active than the other analogous complexes in the transfer hydrogenation (up to 81% ee).     

Synthesis, characterization, and crystal structure of 1-(4-chloro-benzoyl)-3-naphthalen-1-yl-thiourea

1-(4-Chloro-benzoyl)-3-naphthalen-1-yl-thiourea has been synthesized and characterized by elemental analysis, IR spectroscopy, and mass spectrometry. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1, with a = 6.962(1) Å, b = 10.770(3) Å, c = 11.738(2) Å, = 65.76(2)°, = 80.03(1)°, = 84.86(2)°, and D _calc= 1.432 g cm^–1 for Z = 2. The thermal behavior of the compound has been studied by DTA and TG. The antibacterial activities of the title compound were investigated for three Gram (+) and two Gram (–) bacteria by employing broth microdilution method and subsequently, inhibitory activity against yeast-like fungi was also determined.     

On generalized recurrent Riemannian manifolds

The object of the present paper is to study a type of Riemannian manifolds called generalized recurrent manifolds. We have constructed two concrete examples of such a manifold whose scalar curvature is non-zero non-constant. Some other properties have been considered. Among others it is shown that on a generalized recurrent manifold with constant scalar curvature, Weyl-semisymmetry and semisymmetry are equivalent. Sufficient condition for a generalized recurrent manifold to be a special quasi Einstein manifold is obtained.     

Selective addition of H2O to fullerene C60 catalyzed by Ti, Zr, and Hf catalysts

Selective addition of H₂O to fullerene C₆₀ catalyzed by Cp₂MCl₂ (M = Ti, Zr, Hf) catalysts to yield 1-hydroxy-1,2-dihydrofullerene has been realized for the first time.     

Enantioselective sorption of some chiral carboxylic acids by various cyclodextrin-grafted iron oxide magnetic nanoparticles

A new enantioselective sorption approach to chiral carboxylic acid molecules such as (R)-(?)-N-(3,5-dinitrobenzoyl)phenylglycine (R)-(?)DNBPG, (S)-(+)-N-(3,5-dinitrobenzoyl)phenylglycine (S)-(+)DNBPG, (R)-(+)-N-(1-phenylethyl)phthalamic acid (R)-(+)PEPA and (S)-(?)-N-(1-phenylethyl)phthalamic acid (S)-(?)PEPA regarding their complexation with three diversely functionalized β-cyclodextrin grafted iron oxide nanoparticles in the aqueous phase, was developed. The sorption efficiencies of these carboxylic acids were carried out by high-performance liquid chromatography (HPLC) with an Ace 5 C18 column. The effects of temperatures on the sorption were also investigated. The results showed that the ether functionalized derivative of β-cyclodextrin Al-CD-MNPs has a specific affinity for (R)-(?)DNBPG at 30 °C and pH 7.0. The amine functionalized derivative of β-cyclodextrin Am-CD-MNPs has a greater affinity towards not only (S)-(?)DNBPG, but also (R)-(+)PEPA compared with their other isomers, which are the (R)-isomer of DNBPG and the (S)-isomer of PEPA at 30 °C and pH 7.0. In addition, although amide functionalized derivatives of β-cyclodextrin (Amd-CD-MNPs) have an affinity towards both isomers of some chiral carboxylic acids; no selective affinity was observed at 30 °C and pH 7.0.     

Spray‐processable thiazolothiazole‐based copolymers with altered donor groups and their electrochromic properties

Two novel thiazolo[5,4‐d]thiazole containing donor–acceptor type alternating copolymers, poly[2‐(5‐(2‐decyl‐2H‐benzo[d][1,2,3]triazol‐4‐yl)thiophen‐2‐yl)‐5‐(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole] (BTzTh) and poly[2‐(5‐(2‐decyl‐2H‐benzo[d][1,2,3]triazol‐4‐yl)furan‐2‐yl)‐5‐(furan‐2‐yl)thiazolo[5,4‐d]thiazole] (BTzFr) were synthesized by Stille coupling polymerization and their electrochemical and electrochromic properties were explored. Electrochemical activities of the spray‐casted polymer films were determined by cyclic voltammetry. To evaluate the effect of thiophene and furan moieties on the optical properties of the copolymers, spectroelectrochemistry studies were performed. To examine the switching abilities, copolymer films were subjected to a double potential step chronoamperometry in their local maximum absorptions. Both thiazolothiazole‐containing copolymers showed multichromic properties with low band‐gap values 1.7 and 1.9 eV for BTzTh and BTzFr, respectively. The decent electrochromical properties together with solution processability make them important candidates for electrochromic applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3901–3906     

Determination of lead by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS): On-line generation of plumbane using potassium hexacyanomanganate(III)

A hydride generation (HG) procedure has been described for determination of Pb by ICP-MS using potassium hexacyanomanganate(III), K₃Mn(CN)₆, as an additive to facilitate the generation of plumbane (PbH₄). Potassium hexacyanomanganate(III) was prepared in acidic medium as it was unstable in water. The stability of hexacyanomanganate(III) was examined in dilute solutions of HCl, HNO₃ and H₂SO₄. The solutions prepared in 1% v/v H₂SO₄ were found to be stable for over a period of 24 h. The least suitable medium was 1% v/v HNO₃. For generation of plumbane, acidic hexacyanomanganate(III) and sample solutions were mixed on-line along a 5-cm long tygon tubing (1.14 mm i.d.) and then reacted with 2% m/v sodium borohydride (NaBH₄). A concentration of 0.5% m/v K₃Mn(CN)₆ facilitated the generation of PbH₄ remarkably. In comparison to H₂SO₄, HCl provided broader working range for which optimum concentration was 1% v/v. No significant interferences were noted from transition metals and hydride forming elements, up to 0.5 μg mL⁻¹ levels, except Cu which depressed the signals severely. The depressive effects in the presence of 0.1 μg mL⁻¹ Cu were alleviated by increasing the concentration of K₃Mn(CN)₆ to 2% m/v. Under these conditions, the sensitivity was enhanced by a factor of at least 42 to 48. The detection limit (3 s) was 0.008 μg L⁻¹ for ²⁰⁸Pb isotope. Average signal-to-noise ratio (S/N) ranged between 18 and 20 for 1.0 μg mL⁻¹ Pb solution. The accuracy of the method was verified by analysis of several certified reference materials, including Nearshore seawater (CASS-4), Bone ash (SRM 1400), and Mussel tissue (SRM 2976). The procedure was also successfully applied to the determination of Pb in coastal seawater samples by ICP-MS.