分子内Diels-Alder反应在有机合成方面的新进展

本文按合成产物的结构类型,综述分子内 Diels-Alder 反应在有机合成方面的新进展。     

Cyphostemmins A-B, two new antifungal oligostilbenes from Cyphostemma crotalarioides (Vitaceae)

Two new antifungal resveratrol dimers, cyphostemmins A-B (1–2), have isolated from the roots of Cyphostemma crotalarioides planch (Vitaceae) together with resveratrol 3 and previously known reseveratrol dimers (4–7). Structures of these new compounds have been established on the basis of their MS and ¹H and ¹³C NMR spectroscopic data.     

Left invariant special Kähler structures

We construct left invariant special Kähler structures on the cotangent bundle of a flat pseudo-Riemannian Lie group. We introduce the twisted cartesian product of two special Kähler Lie algebras according to two linear representations by infinitesimal Kähler transformations. We also exhibit a double extension process of a special Kähler Lie algebra which allows us to get all simply connected special Kähler Lie groups with bi-invariant symplectic connections. All Lie groups constructed by performing this double extension process can be identified with a subgroup of symplectic (or Kähler) affine transformations of its Lie algebra containing a nontrivial 1-parameter subgroup formed by central translations. We show a characterization of left invariant flat special Kähler structures using étale Kähler affine representations, exhibit some immediate consequences of the constructions mentioned above, and give several non-trivial examples.     

Products and transforms of white-noise functionals (in general setting)

Some sharp results about Weiner and Wick products of whitenoise functionals are obtained. Using the inequality of Wick products we show to what extent scaling transformations, translations, and Sobolev differentiations can be performed on white-noise functionals.This work was supported by the National Natural Science Foundation of China. This paper is an enlargement and revised version of the paper entitled Products and Transforms of White-Noise Functionals (preprint, 1990).     

High-temperature TG/DSC/QMS applications in environmental protection

The decomposition reactions of polystyrene, phenolic resin and a protective undercoating material for automobiles which contains PVC were tested using a new type of thermal analysis — mass spectrometry coupling system for measurements to 1500C or 2000C, which is based on the principle of a two-step skimmer orifice system. The results will be presented, with particular emphasis on the detection sensitivity of the new system for the products of decomposition.The capability of this coupling system to detect even heavy metals such as lead and silver in the waste gases from decomposition or after evaporation at high temperatures will also be demonstrated.     

HPLC study of the binding of sulfinpyrazone to serum albumin

Summary A thin layer chromatographic method for a qualitative screening-test and a quantitative analysis of 2,4,6-TNT, biodegradation products, octogen and hexogen in ammunition wastes was developed using both polar and non-polar modified sorbents. For enrichment a solidphase extraction on LiChrolut® EN followed by removal with methanol/acetonitrile (11 v/v) was chosen. To imitate real samples, spiked tap water samples of known composition were used.     

An aldol approach to the total synthesis of (+)-brefeldin A

A convergent selective route to (+)-brefeldin A (BFA) and 7-epi-BFA was developed, with the crucial C-4/C-5 stereogenic centers were established using Crimmins asymmetric aldolization.     

液相色谱电化学安培检测乳粉中的脂溶性维生素A, E和D3

利用维生素A、D3、E均有电化学活性的特点,采用电化学安培检测,建立了HPLC检测奶粉中的脂溶性维生素A、D3、E的新方法.流动相为甲醇∶水=95∶5(V/V),含0.05 mol/L高氯酸钠.检测器采用玻碳电极,直流安培模式(DC),氧化电位 1.3 V.方法检测限为:VA、VD3、-αVE、-γVE、-δVE分别为0.08、2.3、0.16、0.19、0.28ng.回收率分别为:90.2%~98.2%、91.2%~103%、92.7%~99.5%、92.6%~97.4%、90.7%~98.0%.同紫外检测比较,方法具有灵敏度高、抗干扰强的特点.     

Rapid and simple method for determination of Nepsilon-(carboxymethyl)lysine and Nepsilon-(carboxyethyl)lysine in urine using gas chromatography/mass spectrometry

A new procedure was developed to determine in urine the concentrations of N(epsilon)-(carboxymethyl)lysine (CML) and N(epsilon)-(carboxyethyl)lysine (CEL), the major products of oxidative modification of glycated proteins, to assess levels of oxidative stress in physiological systems. The urine samples were acetonitrile-deproteinized, then derivatized by ethylchloroformate, and N(O,S)-ethoxycarbonyl ethyl esters of amino acids were analysed by isotope dilution gas chromatography/mass spectrometry. Recovery averaged 89%. Linearity was excellent (r = 0.998-0.999) in the 0.5-25 micromol/L range for CML and CEL. The limit of detection of this assay was 0.1 micromol/L (corresponding to 0.20 pmol of CML or CEL on column). Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <4.63 and <6.15%, respectively. Accuracy of CML and CEL determination (15 micromol/L) was 2.9 and 5.9% of the estimated theoretical value. The time from obtaining the urine sample to determination of the concentration from the chromatographic peak was 80 min or less. This method is sensitive, reproducible, accurate, relatively cheap and very simple. It can be useful for laboratories involved in the diagnosis and monitoring of age-related chronic diseases.