Highly efficient synthesis of homoallylic alcohols and amines via allylation of aldehydes and imines catalyzed by ZrOCl2·8H2O in water

The allylation of aldehydes and imines has efficiently been carried out by treatment with allyltributylstannane in the presence of a catalytic amount of ZrOCl₂·8H₂O in water to form the corresponding homoallylic alcohols and amines, respectively, in high yields.     

A new aptameric biosensor for cocaine based on surface-enhanced Raman scattering spectroscopy

The present study reports the proof of principle of a reagentless aptameric sensor based on surface-enhanced Raman scattering (SERS) spectroscopy with "signal-on" architecture using a model target of cocaine. This new aptameric sensor is based on the conformational change of the surface-tethered aptamer on a binding target that draws a certain Raman reporter in close proximity to the SERS substrate, thereby increasing the Raman scattering signal due to the local enhancement effect of SERS. To improve the response performance, the sensor is fabricated from a cocaine-templated mixed self-assembly of a 3'-terminal tetramethylrhodamine (TMR)-labeled DNA aptamer on a silver colloid film by means of an alkanethiol moiety at the 5' end. This immobilization strategy optimizes the orientation of the aptamer on the surface and facilitates the folding on the binding target. Under optimized assay conditions, one can determine cocaine at a concentration of 1 muM, which compares favorably with analogous aptameric sensors based on electrochemical and fluorescence techniques. The sensor can be readily regenerated by being washed with a buffer. These results suggest that the SERS-based transducer might create a new dimension for future development of aptameric sensors for sensitive determination in biochemical and biomedical studies.     

(N,N-Diisopropylcarbamoyloxy)-methyl p-tolyl sulfone: preparation and application for the syntheses of 1,2-diols

1-(N,N-Diisopropylcarbamoyloxy)-1-tosyl-methane (CbOCH₂Ts, Cb=N,N-diisopropylcarbamoyl) was readily prepared from p-TolSH, paraformaldehyde and CbCl. With the dual activation of CbO- and Ts-substitutions, deprotonation of CbOCH₂Ts could be effected not only by n-BuLi, but also by Grignard reagents. Upon deprotonation, the title compound adds to various carbonyl structures. By choosing proper organometallic reagents for consecutive steps, the addition intermediate undergoes in situ conversions to efficiently yield regioselectively O-Cb protected and unprotected 1,2-diols.     

Micromorphology and phase behavior of cationic polyurethane segmented copolymer modified with hydroxysilane

A series of cationic waterborne polyurethane dispersions (SiPU) modified with hydroxysilane (HPMS) were successfully synthesized based on poly(oxytetramethylene) glycols (PTMG) and isophorone isocyanate (IPDI), and the films were obtained by casting the dispersions on tetrafluoroethylene (TFE) plates. Effects of HPMS content on micromorphology, particle size of the dispersions were studied, as well as thermal properties, phase behavior and surface structure of the films. The particles had the morphology of a solid sphere, with particle size varying from 17.1 nm to 114.4 nm corresponding to the increase of HPMS concentration, which can be attributed to the increase of interfacial tension. XPS spectra indicated the surface migration of Si element in the process of film forming, and the SiPU surface was mainly composed of soft segments. DSC analysis, together with TG-DTG-DTA results demonstrated the HPMS soft segment merged with the transition region of PU matrix, forming part of polyurethane backbone, but an improved microphase separation was observed when HPMS concentration greater than 15%. It was also found that incorporation of flexible HPMS prevented the degradation of polyurethane backbone, resulting in the increase of thermal stability in ultimate copolymer.     

几种有机磷农药的热分析研究

本文主要用热重分析法,分别测定了乐果、敌百虫和甲基-1605三种农药热分解反应的动力学参数,进而探讨了热分解机理并计算了室温时的分解时间,对安全生产和确定贮存时间有一定指导意义。     

照相光谱增感染料在溴化银沉淀表面的吸附及吸附热测量

用离心分离法得到25℃菁染料Ⅱ和Ⅲ分别在几种溶剂的溴化银分散系中的吸附等温线;记录了染料溶液的吸收光谱和吸附态染料的反射光谱。采用精密量热技术得到25±0.01℃溴化银从DMF-水溶液中吸附染料Ⅱ等位摩尔吸附热为-(3.18±0.09)KJ/mol(θ=0.87)。还对从DMF溶液中吸附染料Ⅱ的体系绘制了以单位溴化银表面的吸附热表示的吸附等温线,表明用精密量热技术可以研究染料的吸附过程。     

二(2-乙基已基)磷酸(HDEHP)萃取钴(Ⅱ)、镁的研究

本文在25±1℃时考察了HDEHP-煤油/0.1MNaCl体系对Co(Ⅱ)、Mg的萃取.     

Inocalophyllins A,B and their methyl esters from the seeds of Calophyllum inophyllum

Fractionation of the ethanolic extract of the seeds of Calophyllum inophyllum L. has resulted in the isolation of four novel pyranocoumarin derivatives, designated as inocalophyllins A (1), B (2) and their methyl esters (3, 4) in addition to the known calophyllolide. The structures of these compounds have been determined on the basis of spectroscopic analysis including MS, heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and two dimensional incredible natural abundance double quantum transfer experiment (2D-INADEQUATE). Two new methylated products, 5 and 6 were also prepared by methylation of compounds 1 and 2, respectively.     

HAD: an automated database tool for analyzing screening hits in drug discovery

Collecting, organizing, and reviewing chemical information associated with screening hits are human time-consuming. The task depends highly on the individual, and human errors may result in missing leads or wasting resources. To overcome these hurdles, we have developed a decision support system, Hits Analysis Database (HAD). HAD is a software tool that automatically generates an ISIS database file containing compound structures, biological activities, calculated properties such as clogP, hazard fragment labels, structure classifications, etc. All data are processed by available software and packed into a single SD file. In addition to search capabilities, HAD provides an overview of structural classes and associated activity statistics. Chemical structures can be organized by maximum common substructure clustering. The ease of use and customized features make HAD a chief tool in lead selection processes.