Michael Addition Catalyzed by Chiral Secondary Amine Phosphoramide Using Fluorinated Silyl Enol Ethers: Formation of Quaternary Carbon Stereocenters

A chiral secondary amine phosphoramide was developed and identified as a powerful catalyst for the Mukaiyama–Michael addition of fluorinated enol silyl ethers to tetrasubstituted olefins. The resulting products are obtained with high enantioselectivities and contain a quaternary carbon stereocenter bearing either a difluoroalkyl or monofluoroalkyl group.     

Gold‐Catalyzed Fluorination–Hydration: Synthesis of α‐Fluorobenzofuranones from 2‐Alkynylphenol Derivatives

The Au^I‐catalyzed fluorination–hydration of 2‐alkynylphenol derivatives in the presence of Selectfluor [1‐chloromethyl‐4‐fluoro‐1,4‐diazoniabicyclo‐[2.2.2]octane bis(tetrafluoroborate)] has been developed. This method provides straightforward access to α‐fluorobenzofuranones with the construction of C?O, C=O, and C?F bonds in a single step on the basis of an Au^I/Au^III redox catalytic cycle. Several control experiments, including the asymmetric variant of this reaction, were also conducted to gain insight into the reaction mechanism.     

从x出发的漂移Brownian Motion的极值分布

该文研究了从x出发的正漂移Brownian Motion的极值问题，给出了关于这种随机过程的两种极大值的定义，并主要利用Brownian Motion的一些重要性质，比如正交不变性、时空齐次性及在有限停时上的强Markov性等，获得了两种极大值的分布函数的精确表达式。     

Emergent rotational symmetries in disordered magnetic domain patterns

Uniaxial systems often form labyrinthine domains that exhibit short-range order but are macroscopically isotropic and would not be expected to exhibit precise symmetries. However, their underlying frustration results in a multitude of metastable configurations of comparable energy, and driving such a system externally might lead to pattern formation. We find that soft x-ray speckle diffraction patterns of the labyrinthine domains in CoPd/IrMn heterostructures reveal a diverse array of hidden rotational symmetries about the magnetization axis, thereby suggesting an unusual form of emergent order in an otherwise disordered system. These symmetries depend on applied magnetic field, magnetization history, and scattering wave vector. Maps of rotational symmetry exhibit intriguing structures that can be controlled by manipulating the applied magnetic field in concert with the exchange bias condition.     

Electronic structures of N- and C-doped NiO from first-principles calculations

The large intrinsic band gap of NiO has hindered severely its potential application under visible-light irradiation. In this Letter, we have performed first-principles calculations on the electronic properties of N- and C-doped NiO to ascertain if its band gap may be narrowed theoretically. It was found that impurity bands driven by N 2p or C 2p states appear in the band gap of NiO and that some of these locate at the conduction band minimum, which leads to a significant band gap narrowing. Our results show that N-doped NiO may serve as a potential photocatalyst relative to C-doped NiO, due to the presence of some recombination centres in C-doped NiO.     

非酯类拟除虫菊酯研究进展

从结构活性关系和合成方面综述了非酯类拟除虫菊酯的研究进展。     

Synthesis of N-t-Butyl-N'-Aminocarbonyl-N-(Substituted) Benzoylhydrazine Containing a -Aminoalkylphosphonate Groups

A variety of novel N-t-butyl-N'-aminocarbonyl-N-(substituted)benzoylhydrazines containing a -aminoalkylphosphonate groups were synthesized by the addition of N-t-butyl-N-(substituted)benzoylhydrazines to a -isocyanatoalkylphosphonates, which were synthesized by the reaction of a -aminoalkylphosphonates with triphosgene in good yields. The structures of products including by-products were confirmed by 1H NMR, 31P NMR, IR, mass spectroscopy, and elemental analysis.     

Screening and analysis of the multiple absorbed bioactive components and metabolites in rat plasma after oral administration of Jitai tablets by high‐performance liquid chromatography/diode‐array detection coupled with electrospray ionization tandem mass spectrometry

Based on the serum pharmacochemistry technique and high‐performance liquid chromatography/diode‐array detection (HPLC/DAD) coupled with electrospray tandem mass spectrometry (HPLC/ESI‐MS/MS), a method for screening and analysis of the multiple absorbed bioactive components and metabolites of Jitai tablets (JTT) in orally dosed rat plasma was developed. Plasma was treated by methanol precipitation prior to liquid chromatography, and the separation was carried out on a Symmetry C₁₈ column, with a linear gradient (0.1% formic acid/water/acetonitrile). Mass spectra were acquired in negative and positive ion modes, respectively. As a result, 26 bioactive components originated from JTT and 5 metabolites were tentatively identified in orally dosed rat plasma by comparing their retention times and MS spectra with those of authentic standards and literature data. It is concluded that an effective and reliable analytical method was set up for screening the bioactive components of Chinese herbal medicine, which provided a meaningful basis for further pharmacology and active mechanism research of JTT. Copyright © 2010 John Wiley & Sons, Ltd.     

A New Triterpenoid Glycoside from Decaisnea Fargesii

Deculsnea./al..gesiiFranch.IsatraditionalChinesemedicinalplantwidely'distributedinChina.usedasananti-rheumaticandalltitussivedrugforalongtimeinChinesefolkmedicine'.Itsmethanolextractshowedantitunlouracidityif71)if)oagainstS:sl},HepaandEhrlichcellsanditsphytochemicalstudiesonsaponinshasreported'.Asacontinuationofthestudiesonthisplant,wepresentthespectralandchemicalevidenceofthestructureofanewdecaisosideF.Thedriedstems(2.23kg)werepercolated\vith95%EtOH.Afterremovalofthepercolatesb}evaporat…