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.     

Enantioselective Hydroarylation of Olefins Using Palladium/Chiral Quinoline Oxazolines

Palladium-catalyzed arylation and alkenylation of olefins, known as the Heck reaction, is one of the most efficient catalytic methods for carbon-carbon bond formation in organic synthesis^[1]. During the last decade, asymmetric Heck reactions have attracted great attention, and a number of highly enantioselective chiral ligands have been developed to enhance chiral discrimination in these reactions^[2]. However, asymmetric Heck-type hydroarylations of olefins, addition of aryl halides or triflates to carbon-carbon double bonds, have not been well studied. In 1991, Brunner reported an asymmetric hydroarylation of norbornene and norbornadiene with aryl iodides using chiral bisphosphine ligands, and around 40% ee was achieved^[3]. Later on, Achiwa reached around 70% ee in the asymmetric hydroarylation of norbornene with phenyl triflate by using chiral P-N ligands^[4,5]. Herein, we wish to describe our investigations on chiral quinolinyl-oxazoline ligands that provide the first examples of efficient bisnitrogen ligands in Heck-type hydroarylation and the application of this reaction in the asymmetric synthesis of Epibatidine.     

The Chlorination of O-Alkyl S-Alkyl(aryl) Thiophosphoric(-nic) Acid Derivatives with Phosphorus Oxychloride——A New Convenient Method for Synthesis of Chiral S-Alkyl(aryl) Thiophosphoro(-no) Chloridates

In our laboratory, the isomerization/chlorination of a variety of O,O-dialkyl phosphoro(-no)thionates 1 with phosphorus oxychloride have been systematically studied. It was found that when R' equals aryloxy^[1], alkylthio^[2], arylthio^[2], dialkylamino^[3], phenyl^[4], methyl^[5],and nitrogen heterocyclic group^[6] in 1,respectively, this reaction can proceed smoothly and gives the desired products ² and ³. Hence, it provides a general synthitic method for S-alkyl thiophosphoro(-no)chloridates, especially for the asymmetric ones.     

Synthesis of New Phase-Transfer Catalysts and Their Application in Asymmetric Alkylation

Despite phase transfer catalysis (PTC) is an important and useful method in organic synthesis, asymmetric synthesis using chiral phase-transfer catalyst has not been well documented and limited number of chiral phase-transfer catalyst have been developed^[1].In 1989,O'Donnell published his pioneering work in the asymmetric synthesis of α-amino acids by enantioselective alkylation of a prochiral protected glycine derivative using chiral phase-transfer catalyst^[2]. Since then, several groups reported their improvements on enantioselectivity and applicability on this useful synthetic reaction^[3,4]. However, almost all of the chiral phase-transfer catalysts reported so far are the derivatives of cinchona^[5]. In this presentation, we wish to describe the design and synthesis of a new type of chiral phase-transfer catalyst based on the camphor and its application in asymmetric alkylation of tert-bntyl glycinate-benzophenone Schiff base.     

An Asymmetric Synthesis of Isoindolinones

Recently, the results from this laboratory showed that the reductive alkylation of protected (S)-malimide could be achieved in a high regio- and diastereoselective manner. The substituted 2-pyrrolidinones thus formed are versatile chiral building blocks which can be used in the asymmetric synthesis of pyrrolidines^[1,2],2-pyrrolidinones^[3,4] and β-hydroxy-γ-amino acids^[5,6]. As an extension of this work, and in combination with the current interest in the synthesis of isoindolin-1-ones, a study on the asymmetric reductive alkylation of phthalimide derived from (R)-phenylglycinol was undertaken.     

Proton transfer reactions from N-H acid [5,10,15,20-tetrakis(pentafluorophenyl)-21-H, 23-H-porphyrin] to strong bases in acetonitrile

Deprotonation of 5,10,15,20-tetrakis(pentafluorophenyl)-21-H, 23-H-porphyrin (PhF₅PorH₂) by various bases has been studied by ¹H NMR and kinetic methods. The kinetic parameters in acetonitrile were defined for proton transfer reactions yielding [NH]⁺ protonated bases and [NHN]⁻ anions with intramolecular hydrogen-bonded chains.     

A new approach to all—cis triquinane synthesis and a new route to the C16—hexaquinane system

A new synthesis of all-cis triquinanes is presented. The examples bear a cis substituent on the fifth position of the central ring, and are thus all-cis pentasubstituted cyclopentanes. The stereo-controlled addition of organometallics of 7-ketonorbornenes is considered, as is “reductive solvolysis” of such adducts to the corresponding hydrocarbons. The preparation of trans-3,4-dimethoxycyclopentyl chloride is given, as is that of the corresponding organolithium. The use of quinoxaline derivatives in aldol-type reactions is considered, with examples. A new approach to the C₁₆-hexaquinane system is developed. The ring systems reported include: tricyclo-[8.2.1.0^2,9]tridecane, tricyclo[6.3.0.0^3,7]undecane, tetracyclo-[10.1.0.0^2,9.0^10,13]tridecane, pentacyclo[8.5.1.0^2,6.0^7,16.0^11,15]hexadene and hexacyclo(8.5.1.0^2,6.0^3,14.0^7,16.0^11,15]hexadecane.     

可见光敏引发聚合甲基丙烯酸甲酯的动力学研究

本论文用膨胀计法进行了甲基丙烯酸甲酯在氯仿溶液中可见光光敏引发聚合动力学的研究。此光敏引发体系由光敏剂1,3,3-三甲基-2-[5-(1,3,3-三甲基-2-吲哚叉)-1,3-戊二烯]吲哚碘盐(简称NK-529),引发剂邻氯代六芳基双咪唑(简称o-Cl-HABI),氢给体3-巯基-4-甲基-4氢-1,2,4-三氮唑(简称MTA)组成。研究结果表明,此光敏聚合体系的光聚合速率与各组分的动力学方程如下:R_p=K(NK-529)^0.51(HABI)^0.41(MTA)^0.36(MMA)^1.0.     

Characterization of antibodies against benzo[a]pyrene with thermodynamic and kinetic constants

Antibodies of a polyclonal antiserum against benzo[a]pyrene were characterized by determining thermodynamic and kinetic constants of the antigen–antibody reaction. Label-free binding assays with optical detection based on reflectometric interference spectroscopy were performed to determine these constants. Different evaluation methods for kinetic measurements were compared. Also, cross-reactivity against two other polycyclic aromatic hydrocarbons, chrysene and pyrene, was checked. The affinity constant between the antibodies and benzo[a]pyrene in homogeneous phase was determined to be K=(5.3±0.3)×10⁷ M⁻¹ which was in the middle of the usual range of antibody affinities. The association rate constant for the reaction at the surface was determined to be (3.8±0.9)×10⁵ M⁻¹ s⁻¹, the dissociation rate constant as (9.7±0.5)×10⁻³ s⁻¹. Different evaluation methods applied to the kinetic measurements led to the same results. This antiserum would be suitable for the selective determination of benzo[a]pyrene in concentrated samples.     

Kinetic and mechanistic study of the chlorpromazine-hydrogen peroxide reaction for the catalytic spectrophotometric determination of iodide

Extensive kinetic studies were performed to investigate the mechanism of the chlorpromazine (CP)-hydrogen peroxide reaction utilized in the catalytic determination of iodide. This reaction proceeds by two independent, parallel reactions, one through the formation of a red free radical, another directly to form the colorless product. The red color formation is catalyzed by traces of iodide. The color formation reaction was followed by measuring the increase in absorbance at 525 nm and its kinetic investigations were carried out by the initial rate method. The reaction rate curves for colorless sulfoxide formation were obtained by following the increase in absorbance at 335 nm, and the analysis was carried out by the integration method. The disappearance rate of CP is given by -d[CP]dt = k₃[I⁻[H₂O₂][H⁺] + k₆[CP][H₂O₂][H⁺] + k₉[CP][H₂O₂][H⁺] + k₁₀[CP][H₂O₂], where the first and second terms correspond to the chromogenic reaction and the third and fourth to colorless sulfoxide formation. Mechanisms consistent with each term were proposed and analytical implications of the kinetic studies are discussed.     

[OHO] and [NHO] hydrogen bonds in the 2:1 adduct of pentachlorophenol with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene [(PCP)2·MTBD]

The results of X-ray diffraction and IR spectroscopic studies for 2:1 pentachlorophenol-7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene [(PCP)₂·MTBD] adduct are reported. The geometry of MTBD cations reflects the equal distribution of the positive charge among three nitrogen atoms. Short asymmetric [OHO]⁻ hydrogen bonds with OO distance of 2.508(2) Å and NH⁺O⁻ hydrogen bonds with NO distance of 2.802(2) Å are formed showing broad IR absorption with two maxima located at 1200 and 2400 cm⁻¹. The second maximum is interpreted as due to the 0→2 transition between split levels in an asymmetric double minimum potential. One of the oxygen atoms forms an additional OH–N⁺ hydrogen bonding with an MTBD cation. The situation is somewhat different in acetonitrile solution whose IR spectrum shows continuous absorption extended over whole the IR region. In acetonitrile, dissociation to free OHO⁻ and ⁺NH ions takes place and the OHO⁻ bridges become dynamically symmetric. The broadening is interpreted in terms of a stochastic distribution of the geometry and the Zundel polarizability theory.     

手性二环[3.3.0]辛-3-烯类化合物的合成

研究了5-(1-孟氧基)-3-溴-2(5H)-呋喃酮新手性源(1)与某些碳亲核试剂发生的串联不对称Michael加成/分子内亲核取代反应,反应中生成2个新的手性中心得到一般方法难以合成的光学纳二环[3.3.0]辛-3-烯类化合物.通过[α]、IR、UV、¹HNMR、¹³CNMR、MS、元素分析以及X射线四圆衍射等方法确定了手性二环[3.3.0]辛-3-稀类化合物化学结构和绝对构型.     

Hydrothermal Synthesis,Structure and Properties of a New Phosphomolybdate Based on Novel [Co(H2O)4(HP2Mo5O23)]8- Anions and [H8(H2O)16]8+ Water Cluster Cations

A pure inorganic [P₂Mo₅O₂₃]^6- based cobalt complex [H₈(H₂O)₁₆][Co(H₂O)₄(HP₂Mo₅O₂₃)₂] with a sandglass-like shape was synthesized and characterized by means of single-crystal X-ray diffraction, powder X-ray diffraction(PXRD), infrared spectroscopy(IR), thermogravimetry/differential scanning calorimetry(TG/DSC), ultraviolet-visible spectroscopy(UV-Vis) and cyclic voltammogram(CV). Single-crystal X-ray diffraction analysis reveals that the asymmetric unit of compound 1 consists of a half cobalt ion, one [P₂Mo₅O₂₃]^6- anion, two coordinated water molecules and eight lattice water molecules. It is especially intriguing to note that two [P₂Mo₅O₂₃]^6- clusters are symmetrical about the Co ion, like a sandglass. And a chair-like water cluster with an unprecedented centrosymmetric [H₈(H₂O)₁₆]⁸⁺ can be observed in compound 1. Additionally, the electrochemical and catalytic properties of compound 1 were also investigated.     

电荷转移聚合——酚噻嗪及其衍生物引发丙烯腈光聚合

电荷转移引发的聚合近年来受到人们的广泛注意,许多电子给体,如芳香族的胺、醚、硫醚以及含氮芳杂环化合物,都可引发丙烯腈、甲基丙烯酸甲酯等负性单体光聚合,研究表明,其聚合都是通过电荷转移机制引发的^[1-3]。     

Optically active transition metal compounds : LXXXI. Crystal structure of (+)546-[C5H5Mo(CO)2LL]PF (LL = 2-benzoylpyridine-(R)-1-phenylethylimine)

Racemic [C₅H₅Mo(CO)₂LL]PF₆, (2) with LL = 2-benzoylpyridine-1-phenylethylimine, undergoes spontaneous resolution upon crystallization from acetone/CH₂Cl₂/ethanol. The absolute configuration of the (+)₅₄₆-isomer was shown to be (R) at the Mo atom and (R) at the asymmetric carbon atom. Comparison of 2 with [C₅H₅Mo(CO)₂LL]PF₆ (1) (LL = 2-carbaldehydepyridine-1-phenylethylimine) reveals distinct changes caused by the differences resulting from the presence of the phenyl group in 2 and the change from the (RR)- to the (RS)-configuration.     

Kinetics of ring-opening polymerization of octamethylcyclotetrasiloxane in microemulsion

Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane(D4) in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsiner and potassium hydrate as an initiator.The particle size was determined by the dynamic light scattering(DLS) technique and the reaction rates of the polymerization were discussed.Furthermore,the kinetics was studied by an initial-rate method,and the effects of the monomer,emulsiner and initiator concentrations and the temperature on polymerization conversions were investigated.From the kinetic results,the rate of polymerization,R_p at 80 ℃ can be expressed as R_p = k[D4]~(0.79)[OTAC]~(0.64)[KOH]~(0.38) and the apparent activation energy(E_a),which was determined by half-period method,is 95.32 kJ mol~(-1).     

Biomimetic Oxidation of 1-1'-Bi-2-naphthol with Copper(Ⅰ) and Copper(Ⅱ)-amine Complexes

Copper amine complexes were used to mimic oxidases in the biomimetic oxidation of organic compounds^[1]. Masahiro Noji and coworkers^[2] reported the oxidative coupling of 2-naphthol into high yield of 1,1'-bi-2-naphthol (1) by using catalytical amount of CuCl-tetramethylethylenediamine complex at the presence of O₂. Here we report the catalytic oxidation of 1 with copper amine complexes.     

Quantitative aqueous attenuated total reflectance Fourier transform infrared spectroscopy : Part II. Integrated molar absorptivities of alkyl carboxylates

A quantitative attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopic method is developed for the analysis of total carboxylate concentration, [COO⁻], in aqueous solution. The short (12–13 μm) and highly reproducible pathlength of the ATR cell permits quantitative subtraction of the water peak at 1640 cm⁻¹. Carboxylate quantitation is based on the area of the asymmetric stretching peak, which is nearly independent of compound structure. The molar absorptivity of alkyl carboxylates in water is 438 ± 58 l mol⁻¹ cm⁻¹, and the integrated molar absorptivity is 2.95 ± 0.08 × 10⁴ l mol⁻¹ cm⁻² (n = 15 compounds, 0.1 M ≤ [COO⁻] ≤ 1.5 M). The [COO⁻] in solutions of mixed carboxylates is measured with a root mean square error of 2.4% and a small (+1.5) positive bias. The accuracy of the method is limited by the assumption that integrated absorbance is constant for all COO⁻ groups.     

Radiation chemical formation and precipitation of Turnbull blue from Fe(III)-oxalate

The radiation chemical analogue of the light induced formation of Turnbull blue, K[Fe(II)Fe(III)(CN)₆], from K₃[Fe(III)(oxalate)₃] and K₃[Fe(III)(CN)₆] was investigated by pulse radiolysis. The kinetic analysis revealed a two-step process: after a pseudo-first order reaction an autocatalytic formation of Turnbull blue takes place. The rate coefficient of the first step is k₈=1.42×10⁵ M⁻¹ s⁻¹. The incubation time of precipitation was also determined.     

Reactivity of tri- and tetra-nuclear ethylidyne cyclopentadienylcobalt clusters towards protonic acids

The bis(μ₃-ethylidyne) tricobalt cluster [(CpCo)₃(μ₃-CCH₃)₂] (1b) is protonated by trifluoroacetic acid to give the dicobalt edge-protonated cation [H(CpCo)₃(μ₃-CCH₃)₂]⁺ [lb + H]⁺. Protonation of the μ₃-ethylidyne tetracobalt cluster hydride [H(CpCo)₄(μ₃-CCH₃)] (3) takes place in two consecutive steps. At low temperature [H₂(CpCo)₄(μ₃-CCH₃)]⁺ [3 + H]⁺ is formed first, and is then slowly converted into [H₃(CpCo)₄(μ₃-CCH₃)]²⁺ [3 + 2H]²⁺ by an excess of acid. As judged by the ¹H NMR data and the crystal structure of [3 + X]⁺[(CF₃COO)₂X]⁻ (X = H or D) the endo hydrogens in [3 + H]⁺ and [3 + 2H]²⁺ occupy μ₃-(Co₃) face capping hydridic positions. The cations [1b + H]⁺ and [3 + H]⁺ show hydride fluxionality in solution, which in the case of [3 + H]⁺ can be frozen out on the NMR timescale at low temperature (ΔG ^≠ (203 K) = 40.8 kJ/mol). The structure of [3 + X]⁺ [(CF₃COO)₂X]⁻ (X = H or D) was determined by X-ray crystallography. One of the hydrides/deuterides is located on the crystallographic mirror plane, capping a tricobalt face of the cluster cation. The other endo hydrogen atom is believed to be disordered between the other two μ₃-(Co₃) sites, which are related by space group symmetry. Deuteronation of 3 shows a strong normal kinetic deuterium isotope effect. From the temperature independence of the ¹H NMR spectrum of [3 + 2D]²⁺ a non-fluxional solution structure can be inferred. In all the systems studied, hydridic (μ₂- or μ₃-) sites are thermodynamically preferred to possible isomeric agostic CoHC or Co₂HC sites for the endo hydrogens. Agostic interactions cannot, however, be ruled out in transient intermediates during the course of the protonations.