Asymmetric Synthesis Using Sulfinimines (N-Sulfinyl Imines)

Abstract

Sulfinimine-derived polyfunctionalized chiral building blocks, often prepared in one pot, provide efficient access, with a minimum of chemical manipulation, to enantiopure, multifunctional amine derivatives including piperidines and pyrrolidines.     

Some Mo¨ssbauer and X-ray investigations of theα2-Snformation during the reduction of SnCl2 water solutions

Tin structures with very high values of the isomer shifts (δ = +4.3 ± 0.1 mm/sec and δ = +7 ± 0.4 mm/sec) of the Mo¨ssbauer lines, have been observed not only in thin tin films but also in bulk samples. The samples have been obtained by the reduction of SnCl₂ water solutions with Mg, carried out either in the presence of ferromagnetic impurities (Fe, Co, Ni) or in an external magnetic field. The parallel X-ray studies are in accordance with the RHEED observations of thin tin films. The temperature dependence of the Mo¨ssbauer effect on samples rich inα₂-Snhas been studied and microcalorimetric measurements on samples containingβ₁-Snandα₂-Snhave also been performed.     

Asymmetric synthesis of the quinolizidine alkaloid (-)-epimyrtine with intramolecular Mannich cyclization and N-sulfinyl delta-amino beta-ketoesters

A concise, six-step, enantioselective synthesis of (-)-epimyrtine employing the N-sulfinyl delta-amino beta-ketoester chiral building block is described.     

新型硫脲分子-Gd(Ⅲ)配合物对氟离子的选择性识别研究

设计合成了受体分子[[4-[(硫代碳酰氨基)氨甲基]苄基]氨基]硫脲-Gd(Ⅲ)配合物(LH-GdⅢ),研究了其UV-Vis吸收光谱对阴离子的响应.发现受体的DMSO溶液中加入F-后,吸收光谱强度发生极大变化,并于426nm处产生新的吸收峰,且观察到清晰的等吸收点.研究表明氟离子以1:1结合模式影响体系的吸收,该受体分...     

Mössbauer study of amorphous Fe40Ni40PxB20−x

The hyperfine field distributions of amorphous Fe₄₀Ni₄₀P_xB_20?x (x=10, 12, 14, 17) samples before and after different heat treatments have been determined by means of Mössbauer spectroscopy. All of these P(H) curves are characterized by a main high field maximum and an additional low field maximum, respectively. The asymmetry of distributions of high field component in P(H) of Fe₄₀Ni₄₀P_xB_20?x increases progressively from Fe₄₀Ni₄₀P₁₀B₁₀ to Fe₄₀Ni₄₀P₁₇B₃. The distributions of low field component in P(H) are affected differently by the annealing temperature. The results indicate that the phospoorus element plays an important role in the hyperfine interactions of amorphous Fe₄₀Ni₄₀P_xB_20?x The influence of annealing atmosphere has been discussed.     

Oxidation of carbon monoxide and hydrogen on the surface of crystalline and amorphous Cu60Zr40 alloys

The activity of amorphous and crystalline Cu₆₀Zr₄₀ alloys has been studied. Preoxidation of the alloys results in enhanced activity. The amorphous samples reveal a lower catalytic activity. An active catalyst for the oxidation of CO is obtained from the crystalline copper-zirconium alloy.     

Acoustic attenuation in ferroelectric Sn<Subscript>2</Subscript>P<Subscript>2</Subscript>S<Subscript>6</Subscript> crystals

The temperature and frequency dependencies of sound attenuation for the proper uniaxial ferroelectric Sn₂P₂S₆, which has a strong nonlinear interaction of the polar soft optic and fully symmetrical optic modes that is related to the triple well potential, were studied by Brillouin spectroscopy. It was found that the sound velocity anomaly is described in the Landau-Khalatnikov approximation with one relaxation time. For explanation of the observed temperature and frequency dependencies of the sound attenuation in the ferroelectrric phase, the accounting of several relaxation times is needed and, for quantitative calculations, the mode Gruneisen coefficients are more appropriate as interacting parameters than are the electrostrictive coefficients. Relaxational sound attenuation by domain walls also appears in the ferroelectric phase of Sn₂P₂S₆ crystals.     

Thermal expansion of Sn2P2S6 crystals

We present the results for thermal expansion coefficients of Sn₂P₂S₆ crystals determined both in the crystallographic system and the system based on eigenvectors of thermal expansion tensor. Peculiarities of temperature evolution of the indicative surface of thermal expansion tensor for Sn₂P₂S₆ are discussed, including the region of their ferroelectric phase transition.