Spherical Particles of Zirconia-Titania of Hexagonal Structure from a Neutral Amine Route

Through the sol–gel process, using the so-called neutral amine route, spherical particles of 1:1 zirconia–titania were synthesized from zirconium(IV) and titanium(IV) butoxides as well as 1,12-diaminododecane as precursor species. The obtained product exhibited a hexagonal structure, as determinated by X-ray diffraction data. The obtained material was also characterized by thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, and surface area measurements. Despite the release of template molecules on heating, the spherical morphology was retained up to about 1200°C, at which the disruption of the spheres took place.     

激发态Ti＋(3d14s2)与丙炔醇气相反应理论研究

用量子化学密度泛函(DFT)方法研究了激发态Ti^＋(3d¹4s²)与丙炔醇(PPA)气相反应的机理. 在B3LYP/DZVP水平上, 优化了反应的两个通道的反应物、中间体、过渡态和产物的几何构型, 并在MP4/[6-311＋G**(C,H,O)＋Lanl2dz (Ti)]水平上计算了各驻点的单点能量. 为了确证过渡态的真实性, 在B3LYP/DZVP水平上进行了内禀坐标(IRC)计算和频率分析, 获得了二重态反应势能面, 确定了反应机理. 研究结果表明生成产物为[C₃H₃O]^＋和Ti—H的通道是主要反应途径.     

手性高效液相色谱法测定1—（6‘—甲氧基萘）乙醇不对称氢酯基化反应

在自制的硅基纤维素－三（３，５－二甲基苯基氨基甲酸酯）高效液相色谱手性固定相上（ＨＰＬＣ－ＣＳＰ），优化了１－（６＇－甲氧基萘）乙醇氢酯基化反应产物－萘普生甲酯手性分离的条件，测定了相应的一系列不对称氢酯基化反应产物的对映体过剩值（ｅ．ｅ．值）。结果表明，在ＣＤＭＰＣ－ＣＳＰ手性柱上用ＨＰＬＣ测定此类不对称催化反应的光学产率，评价催化剂体系的手性选择是一种非常理想的方法。     

Crystallization-induced asymmetric transformation of chiral-at-metal ruthenium(II) complexes bearing achiral ligands

Recently, we observed that the enantiopure Lambda form of the tributylammonium salt of the chiral anion tris[tetrachlorobenzene-1,2-bis(olato)]phosphate, also named Trisphat, was able to induce an efficient resolution of a Delta,Lambda racemic mixture of cis-[Ru(dmp)2(NCCH3)2](PF6)2 (dmp=2,9-dimethyl-1,10-phenanthroline) due to the spontaneous and selective precipitation of the heterochiral pair [Delta-Ru(dmp)2(CH3CN)2][Lambda-Trisphat]2. We report here that the combination of such a stereoselective precipitation process and irradiation results in the quantitative conversion of the initial [Ru(dmp)2(NCCH3)2]2+ racemate into only one of the two enantiomers. This is the first example in inorganic chemistry of an asymmetric transformation that leads to a chiral complex with no chiral ligand. Finally, three new racemic ruthenium bis(diimine) complexes, namely [Ru(dmp)2(NCCH3)Py](PF6)2 (Py=pyridine), [Ru(dmp)2(1,3-diaminopropane)](PF6)2, and [Ru(dmp)2(ethylenediamine)](PF6)2 were synthesized. For all of them, crystallization-induced asymmetric transformation proved to be an efficient way of obtaining the corresponding optically active chiral-at-metal complexes in high yields and with excellent stereoselectivities.     

Chiral amplification in macromolecular helicity assisted by noncovalent interaction with achiral amines and memory of the helical chirality

Poly[(4-carboxyphenyl)acetylene] (poly-1) exhibits an intense induced circular dichroism (ICD) in the UV-visible region upon complexation with excess (R)-1-(1-naphthyl)ethylamine ((R)-2), owing to the formation of a predominantly single-handed helical conformation of the polymer backbone. In the presence of a small amount of (R)-2, poly-1 showed a very weak ICD due to the lack of a single-handed helical conformation. However, we have found that the co-addition of the excess bulky, achiral 1-naphthylmethylamine (5) with a small amount of (R)-2 caused a dramatic increase in the ICD magnitude, comparable to the full ICD induced by excess (R)-2. This indicates that an almost single-handed helix can be induced on poly-1 upon complexation with a small amount of (R)-2 assisted by achiral 5. Furthermore, the induced single-handed helical poly-1 could be successfully memorized by the replacement of (R)-2 and 5 with achiral 2-aminoethanol or n-butylamine.     

手性亚砜法合成粉 虫性信息素

5-氯-2-戊酮(2)经四步反应制得(R)-(+)-4-甲基-3-戊烯基对甲苯基亚砜(6), 化合物6与乙醛进行不对称加成反应得手性醇(7), 7经兰尼镍还原性脱硫反应即合成出目标产物粉 虫性信息素(1), 其光学纯度可达45%。     

Chiral ditopic receptors. Application to palladium-catalyzed allylic alkylation

Chiral pyridinooxazoline, quinolinooxazoline, bis(oxazolino)pyridine (pybox), and bisoxazoline (box) derivatives containing crown ether residues were prepared. Some of the ligands were assessed in substrate binding studies and in palladium catalyzed allylic alkylations.     

手性氨基酚配体及其衍生物在不对称催化中的应用

综述了手性氨基酚配体及其衍生物的研究进展, 着重介绍其在不对称催化烷基化、烯基化、Michael加成、aldol反应及环丙化等反应中的应用.     

Conversion of N-Acyl-4-phenyl/benzyl-oxazolidine-2-thiones into Thiol Esters in the Presence of EtSH-K2CO3

N-Acyl-β-hydroxy-4-phenyl-oxazolidinethiones could be rapidly converted into their ethyl thiol esters in high yields by treatment with EtSH at 0 ℃ in CH3CN or 9 ： 1 （V ： V） THF-H2O in the presence of a catalytic amount of K2CO3.     

Resolution of seven-coordinate complexes

The crystal structures of [Pr(dbm)3H2O] (1), [Sm(dbm)3H2O] (2), and [Er(dbm)3H2O] (3) have been determined (dbm=dibenzoylmethane). They display seven-coordinate propeller-shaped molecules, which are chiral and crystallize as conglomerates in space group R3. Analysis of the crystal structures reveals supramolecular interactions, including formation of a quadruple helix, which explain how stereochemical information can be transferred between stacks of molecules. A method to quantify the ee in bulk samples of stereochemically labile compounds by using solid-state CD spectroscopy is described. Using this method, it has been shown that compounds 1-3 undergo total spontaneous resolution directly after synthesis, forming a microcrystalline reaction product that is essentially enantiopure. The resolution of bulk quantities of seven-coordinate complexes (without chiral or polydentate ligands) is thus reported for the first time. Because the crystallization starts without seeding, the overall preparation may be regarded as absolute asymmetric synthesis.