Polymer‐Supported Thiocyanate as New,Versatile and Efficient Polymeric Reagent for Conversion of Alkyl Halides to Corresponding Alkyl Thiocyanates under Mild Conditions

Crosslinked poly(N‐methyl‐4‐vinylpyridinium)thiocyanate [P₄‐Me]SCN (II) is prepared easily and is used as a new polymeric reagent for synthesis of alkyl thiocyanates from alkyl halides under mild and nonaqueous conditions. The used polymeric reagent usually can be removing quantitatively and be regenerated.     

Influence of catalytic system composition on formation of adamantane containing ketones

The preparation of non-symmetrical ketones by the reaction of acyl chlorides and the corresponding Grignard reagents in the presence of catalytic amounts of metal halides is described. The composition of catalyst has a great influence on the yield of the required ketone as well as on side product formation. For each catalytic system, the yield of ketone and the number of side products changes with the time of addition of the Grignard reagent. We examined the influence of both factors in our model reaction of adamantane-1-carbonyl chloride with ethylmagnesium bromide and discussed the possible mechanisms from this point of view. We have found ZnCl₂, MnCl₂, AlCl₃ and CuCl to be active catalytic components and developed very efficient, cheap and fast methods for the preparation of alkyl adamantyl ketones. The procedure was also tested for the synthesis of other alkyl aryl ketones.     

A new reagent system for installation of an aryl group onto the monoacetate of 4-cyclopentene-1,3-diol

Among the three types of reagents from PhMgX (X=Br, Cl) and CuCN for phenylation of 4-cyclopentene-1,3-diol monoacetate, PhMgCl/CuCN (cat.) and Ph₂Cu(CN)(MgCl)₂ in THF afforded the trans-1,4-isomer efficiently (82-87% yields, 91-93% regioselectivity). Similarly, o- and p-RC₆H₄MgCl (R=Me, OMe, CH₂CH) in combination with CuCN furnished good to excellent reactivity and regioselectivity. As an application, a three-step synthesis of dihydromultifidene was accomplished successfully.     

新试剂DCNDAAN与镉显色反应的研究

新试剂2,6-二氯-4,4′-二硝基苯基重氮氨基偶氮苯(DCNDAAN)对镉有较灵敏的显色反应,在Triton X-100存在下,于pH 8.0的硼砂-盐酸缓冲介质中,配合物最大吸收波长为530nm,表观摩尔吸光系数为1.46×10~5。Cd(Ⅱ)量在0～11μg/25ml内符合比耳定律。文章报道了它的合成及光度性能,通过20种新合成的此类试剂与镉的显色反应,探讨其结构与吸光性能的关系。     

Preparation of highly functionalized arylmagnesium reagents by the addition of magnesium phenylselenide to arynes

The described polyfunctional arylmagnesium reagents, resulting from the highly regioselective addition of magnesium phenylselenide to functionalized arynes, can be trapped by a range of electrophiles, yielding polyfunctional selenoethers in 45-85% yields. Furthermore, these Grignard reagents can be used in Negishi cross-coupling reactions with iodoarenes after transmetalation to the corresponding arylzinc compounds, furnishing functionalized biaryl products in 55-73% yields.     

1,1,3,3,3-Pentafluoropropene secondary amine adducts new selective fluorinating agents

Addition of secondary amine SA (dimethylamine DMA, diethylamine DEA, pyrrolidine Pyr, piperidine Pip, morpholine Mor) to pentafluoropropene PFP gives rise to generation of mixtures of two products (1-dialkylamine-1,3,3,3-tetrafluoropropene and N,N-dialkyl-1,1,3,3,3-pentafluoropropylamine) in different ratios. Those reaction mixtures, however, were found to be efficient fluorinating agents replacing hydroxyl groups in alcohols into fluorine. In general, they react with alcohols yielding corresponding fluorides, equimolar amounts of appropriate 3,3,3-trifluoropropionamide and hydrogen fluoride. Aliphatic primary alcohols including octanol and benzylic alcohol yield only alkyl fluorides. The secondary and tertiary alcohols, beside the desired fluorides, give usually considerably amount of alkenes.     

A facile stereoselective synthesis of (E)-1,2-disubstituted vinylstannanes via hydromagnesiation of alkylarylacetylenes

Hydromagnesiation of alkylarylacetylenes 1 in diethyl ether gave (E)-α-arylvinyl Grignard reagents 2, which reacted with trialkylstannyl chlorides 3 in diethyl ether to afford stereoselectively (E)-1,2-disubstituted vinylstannanes 4 in high yields.     

Spectrofluorimetric Determination of Cu2＋ Using New Fluorogenic Reagent

A new synthesized fluorogenic reagent,8-[(2-pyridine)methylideneamino] quinoline (PMAQ), was utilized for spectrofluorimetric determination of Cu(II) at trace levels. PMAQ, a good fluorogenic reagent, though insoluble in water, but is soluble in ethanol and 20% ethanol-water. The excitation and the fluorescence wavelengths of PMAQ were 310 and 434 nm respectively. When the reagent was complexed with Cu(II), the fluorescence intensity decreased proportionally with the concentration of Cu(II) at pH 4.5 by a static quenching effect. The highest sensitivity to Cu^2＋ determination was shown to be at PMAQ concentration of 1.0×10^－5mol•L^－1. In order to enhance the quenching effect, the Cu(II)-PMAQ complex solution was kept at 22 ℃ for 20 min. Though the interferences by Co(II) and Fe(III) were very serious, they were however, completely eliminated by being masked with oxalate and ascorbate ions respectively. The linear dynamic range for Cu(II) determination was between 25—441 µg•L^－1 with the detection limit of 18 µg•L^－1 (RSD＝3.7%, n＝6). The proposed method was successfully applied to the determination of Cu(II) in real samples including human blood serum, commercial tea and wheat flour.     

有机膦、胂试剂的化学及其应用的进展

本文简要地介绍近年来膦、胂叶立德,PO 稳定的碳阴离子的化学及其应用的新进展。     

Simple and convenient synthesis of tertiary benzanilides using dichlorotriphenylphosphorane

Various tertiary benzanilide derivatives were effectively synthesized from substituted benzoic acid and N-monoalkylated aniline using dichlorotriphenylphosphorane in chloroform. Yields were generally high, even when an electron-withdrawing group substituted the aromatic ring of aniline, or when an electron-donating group substituted the aromatic ring of benzoic acid. Allyl, Boc, MPM and the Z group were unaffected under these conditions.