脂肪酶催化苯甘氨酸甲酯两对映体的氨解反应

从6种脂肪酶中筛选出对苯甘氨酸甲酯具有较高氨解反应活性及较高对映体选择性的脂肪酶Novozym435,并研究了铵盐量、温度、有机溶剂及初始水活度对两种对映体的氨解反应的影响,当以叔丁醇为反应介质,反应温度为30℃,铵盐量为15.6mg,初始水活度为0.75时,酶表现出较高的氨解反应活性和对映体选择性。     

Synthesis and characterisation of hexagonal molybdenum nitrides

Four hexagonal molybdenum nitrides—three modifications of δ-MoN and Mo₅N₆—were prepared by the plasma-enhanced chemical vapour deposition (PECVD) method and ammonolysis of MoCl₅ and MoS₂. The nitrides were structurally characterised by X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction. δ₁-MoN is best described by the WC-type structure with stacking faults due to nitrogen atom disorder. Ordering of nitrogen atoms results in δ₂-MoN with the NiAs-type structure. Formation of trigonal molybdenum clusters in δ₃-MoN is responsible for the doubling of the unit cell in a and b directions compared to δ₂-MoN. Mo₅N₆ can be viewed as an intergrowth structure of the WC- and NiAs-type building blocks, accompanied by vacancies on Mo sites. Influence of reaction conditions on the formation of the four nitrides is discussed; their magnetic properties are presented.     

Early introduction of the amino group to the C27–C35 building block of Eribulin

A new synthetic strategy towards the C27–C35 subunit of Eribulin (1) has been devised to include a protected 1,2-amino alcohol at C34–C35. Early introduction of the C35 amino group in the synthesis of 1 increases the efficiency of the route. This new approach can be accomplished on a multi-gram scale and allows for the successful synthesis of Eribulin.     

Synthesis of urea acetates as potential PPARα/γ dual agonists

In the quest for novel PPARα/γ dual agonists as putative drugs for the treatment of type 2 diabetes and dyslipidemia, we designed and synthesized a series of urea acetates as potential PPARα/γ dual agonists. The structure of the target compounds, intermediates were characterized by ^1H N-MR, HRMS.     

Stepwise conversion of a single source precursor into crystalline AlN by transamination reaction

Ammonolysis of the monomeric, base-stabilized trisaminoalane Me₃N-Al[N(H)Dipp)]₃ (Dipp=2,6-ⁱPr₂-C₆H₃) yielded Al-N oligomers, which were characterized in detail by solid state NMR spectroscopy (¹H, ¹³C, ¹⁵N, ²⁷Al) and TGA/DTA. Pyrolysis of as-prepared oligomers at different temperatures in an argon steam yielded carbon-containing black solids, whereas pyrolysis under a steady flow of NH₃ produced pure aluminum nitride (AlN). The role of the pyrolysis temperature and the influence of NH₃ on the formation of crystalline materials were investigated. As-prepared AlN was characterized by solid state NMR spectroscopy (¹⁵N, ²⁷Al), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). Theoretical calculations were performed in order to identify potential reaction intermediates.     

Topotactical growth of thick perovskite oxynitride layers by nitridation of single crystalline oxides

Thick films of the perovskite-related oxynitrides LaTiO₂N, NdTiO₂N, SrNbO₂N and SrTaO₂N were synthesised by nitridation of single crystals of the corresponding oxides with general composition ABO_3.5. The oxide crystals were obtained by optical floating zone growth. They correspond to n = 4 member of the A_nB_nO_3n+2 family of layered perovskites and were reacted at temperatures between 900 °C and 1050 °C to form the oxynitrides. Electron probe microanalysis proved the presence of nitrogen in a surface layer of a few micrometer thickness. Cross-section SEM revealed additional thin stripes of oxynitride within the bulk of the crystals, indicating that nitrogen is incorporated preferably parallel to the perovskite-type layers, which in turn are connected in a zipper-type mechanism. The formation of the desired perovskite-type oxynitrides was confirmed by X-ray diffraction. Pole figure measurements proved an epitaxial orientation ABO₂N (110)[001]  ABO_3.5 (001)[100]. The mosaicity of the oxynitrides both in polar and azimuthal direction was very small (<2°) indicating a nearly single crystalline quality of the surface layer. The nitridation of the crystals results in a dramatic change in colour. Optical spectroscopy revealed shifts of the absorption edge by more than 200 nm to longer wavelengths with respect to the parent oxides, corresponding to a reduction of the band gap energies by 1.4–1.8 eV.     

Synthesis and glycosidase inhibition of C-7 modified casuarine derivatives

A series of C-7 modified analogues of casuarine have been synthesized from sugar-derived nitrone and assayed against various glycosidases. Introduction of C-7 aminomethyl or amide group led to sharp decrease of the inhibitory activities.     

A new anatase-type phase in the system Mg-Ta-O-N

Magnesium doped tantalum oxynitrides were prepared by ammonolysis of amorphous mixed oxides. An orange colored anatase-type phase with the composition Mg_0.05Ta_0.95O_1.15N_0.85 was found. It is metastable and undergoes a phase transformation to a baddeleyite-type phase between 900 and 1000 °C. X-ray diffraction measurements indicate spacegroup I4₁/amd with lattice parameters and . A possible anion ordering was examined by theoretical methods and neutron diffraction experiments. In addition, anosovite-type (Ti₃O₅) phases Mg_xTa_3−xO_3xN_5−3x; 0?x?0.3 were obtained. The electronic spectra of all phases were investigated by UV/vis spectroscopy.     

Ammonolysis of 1,2‐Bis[dichloro(methyl)silyl]ethane. On the Structure of 1,3,6,8‐Tetramethyl‐2,7,11,12‐tetraaza‐1,3,6,8‐tetrasila‐tricyclo[6.2.1.13,6]‐dodecane

Ammonolysis of 1,2‐bis[dichloro(methyl)silyl]ethane afforded a crystalline tricyclic silazane along with polymeric material. The crystalline material could be isolated in pure state. It was analyzed by ¹H, ¹³C, ¹⁵N and ²⁹Si NMR spectroscopy in solution, by ¹³C, ¹⁵N and ²⁹Si MAS NMR spectroscopy in the solid state, as well as by single‐crystal and powder X‐ray diffraction. The title compound exists as a single isomer in solution, whereas in the solid state the presence of several modifications is indicated, in particular by the solid‐state MAS NMR spectra.     

On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3-GaN

We investigated the ammonolysis of β-Ga₂O₃ at elevated temperatures by means of ex situ X-ray diffraction, ex situ neutron diffraction and in situ X-ray absorption spectroscopy. Within the detection limits of these methods, we can rule out the existence of a crystalline or amorphous oxynitride phase that is not derived from wurtzite-type GaN. No evidence for a β-Ga₂O₃ related oxynitride phase was found, and the nitrogen solubility in β-Ga₂O₃ was found to be below the detection limit of about 2-3 at% in the anionic sublattice. These findings were obtained by monitoring the anionic occupancy factors and the lattice parameters of the β-Ga₂O₃ phase obtained from total diffraction pattern refinement with the Rietveld method and by linear combination fitting of the X-ray absorption spectra that were recorded during the ammonolysis.