A simple and easy access to 3-N-alkyl-5-vinyloxazolidinones mediated by palladium-phosphine catalysts

A new entry for the synthesis of 3-alkyl substituted 5-vinyloxazolidin-2-one derivatives 2 from cis-2-butenylene-1,4-dicarbonate 1 and primary amines mediated by palladium-phosphine catalysts is described. The scope and limitation, a plausible mechanism, and an asymmetric version of the reaction are also discussed.     

Transition metal carbene chemistry 2: kinetic studies on the nucleophilic substitution reactions of (CO)5MC(SCH3)CH3 (M = Cr and W) with morpholine in aqueous acetonitrile

Kinetic studies of the aminolysis of [methyl(thiomethyl)carbene]pentacarbonyl chromium(0),(CO)₅CrC(CH₃)(SCH₃) (1-Cr(S)) and [methyl(thiomethyl)carbene]pentacarbonyltungsten(0), (CO)₅WC(CH₃)(SCH₃) (1-W(S)), with morpholine, a secondary amine, in 50% acetonitrile-50% H₂O (v/v at 25 °C) is reported. The second-order rate constant (k_A in m⁻¹ s⁻¹) increases with amine concentration, giving a linear dependence with an intercept on the rate axis and a tendency towards leveling off at higher amine concentration. The reaction was found to undergo general base catalysis. The mechanism proposed is very similar to those for ester reactions, involving a nucleophilic addition of amine to the substrate to yield a zwitterionic tetrahedral intermediate in the first step, followed by deprotonation to form in the second step, which, in the third step, converted to product by H₂O and/or conjugate acid of the base (BH⁺), assisted MeS⁻ expulsion. The reactivity (k₁) of 1-W(S) was found to be higher than that of 1-Cr(S), whereas, comparable , water catalyzed and , BH⁺ catalyzed, leaving group departure were found for both the carbenes complexes. All these observations have been explained successfully.     

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

Neutral forms of hydroxylamine, N-methylhydroxylamine, and N,N-dimethylhydroxylamine are typical α-nucleophiles in water. In comparison with aryl anions of similar basicity their rate of reaction in the decomposition of 4-nitrophenyl diethylphosphonate is increased by about 10² times. Decomposition of the substrate is accelerated in cetyltrimethylammonium bromide micelles (about 4 to 30 fold). Hydroxylamine and its N-alkyl derivatives are the most effective low basicity nucleophiles. The sole factor responsible for the micellar effects is the concentration of the reagent in the surfactant micelles. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 231–236, July–August, 2007.     

杂原子Y分子筛的二次合成及其吸附脱硫性能

采用液-固相同晶取代反应制备了骨架含Ga的Y型分子筛, 并对其吸附脱硫性能进行了研究. 在室温, 空速为7 h−1的条件下, 镓化Y型分子筛([Ga]AlY)处理噻吩、四氢噻吩、4,6-二甲基二苯并噻吩(4,6-DMDBT)正壬烷溶液(硫含量500 μg•g−1), 每克吸附剂吸附硫的量分别为7.7、17.4、14.5 mg. 采用密度泛函理论(DFT)中的广义梯度近似方法(GGA)计算各分子中硫原子上的电荷数, 噻吩中硫原子的电荷数为−0.159, 而4,6-DMDBT和四氢噻吩分别为−0.214、0.298. 四氢噻吩和4, 6-DMDBT中硫原子上的电子密度大于噻吩中硫原子上的电子密度, 这就使得四氢噻吩和4,6-DMDBT中的硫原子与吸附位间的作用会远大于噻吩中的硫原子与吸附位间的作用, 吸附容量必然会大很多. 采用[Ga]AlY处理抚顺石油二厂的催化裂化汽油(硫含量：299 μg•g−1), 每克吸附剂处理2.1 mL汽油时, 处理后汽油的硫含量为54.8 μg•g−1, 说明[Ga]AlY对汽油脱硫有一定的效果.     

A new method for the synthesis of CF3-containing aminovinyl ketones

A new method for the synthesis of aminovinyl trifluoromethyl ketones was developed. The method is based on the reactions of 4-sulfonyl-1,1,1-trifluorobut-3-ene-2,2-diols with various alkyl-, aryl-, dialkyl-, and alkylarylamines. The stereochemistry of the compounds obtained was studied.     

Additions- und SubstitutionsReaktionen an Tetrafluor- und Tetrachlordiboran(4)

Addition and Substitution Reactions at Tetrafluoro- and Tetrachlorodiborane(4) From equimolar mixtures of B₂F₄ and Me_nN(SiMe₃)_3-n (n = 0–3) the mono-addition products 1–4 are formed at low temperatures. By elimination of Me₃SiF the adduct 2 gives the dimeric monosubstituted diborane 8 , which slowly decomposes at room temperature to the aminoborane 6 and (BF)_n. The course of the reactions was studied by means of ¹¹B and ¹⁹F NMR spectroscopy and by measuring the vapor pressures. According to the ¹¹B and ³¹P NMR spectra the reaction of B₂Cl₄ with PCl₅ or [Me₄N]Cl in liquid hydrogen chloride at 0°C does not yield [PCl₄]₂⁺[B₂Cl₆]^2? or [Me₄N]₂⁺[B₂Cl₆]^2? but gives [PCl₄]⁺[BCl₄]^?, PCl₃ and BCl₃ or [Me₄N]⁺[BCl₄]^? and BCl₃ besides (BCl)_n.     

A New 4.0-Generation Dendrimer Phosphorescence Labeling Reagent and Its Application to Determination of Trace Alkaline Phosphatase by Affinity Adsorption Solid Substrate-room Temperature Phosphorimetry

A Triton X-100-4.0G-D （4.0G-D refers to a 4.0-generation dendrimer） was brought forward as a new phosphorescence labeling reagent. Two types of specific affinity adsorption （AA） reactions （direct method and sandwich method） were carried out between the labeling product of Triton X-100-4：0G-D-Wheat germ agglutinin （WGA） and alkaline phosphatase （ALP）, the product of AA reaction preserved the good characteristics of room temperature phosphorescence （RTP） of 4.0G-D and △Ip of the product was proportional to the content of ALP. According to the fact stated above, a new method for the determination of trace ALP by affinity adsorption solid substrate-room temperature phosphorimetry （AA-SS-RTP） was established on the basis of WGA labeled with the Triton X-100-4.0G-D. The detection limits were 0.20 ag·spot^-1 （corresponding concentration： 5.0×10^-16 g·mL^-1, namely 5.0×10^-18 mol·L^-1） for a direct method and 0.14 ag·spot^-1 （corresponding concentration： 3.5×10^-16 g·mL^-1, namely 3.5×10^-18 mol·L^-1） for a sandwich method, respectively. For their high sensitivity, good repeatability and high accuracy, the direct method and sandwich method have been successfully appfied to determine the content of ALP in human serum, and the results were coincided with the clinical detection results of the enzyme-linked immunosorbent assay method by the Zhangzhou Hospital of Traditional Chinese Medicine. Meanwhile, the mechanism for the determination of trace ALP by AA-SS-RTP was discussed.     

On the reaction of 4-substituted trimethyltin aromatics with perchlorylfluoride

To evaluate the suitability of [¹⁸F]perchorylfluoride [¹⁸F]FClO₃ as an electrophilic fluorination agent for the preparation of radiopharmaceuticals, the reactivity non-radioactive FClO₃ towards 4-substituted trimethyltin aromatic compounds was studied. Contrary to the expectation, an electrophilic fluorination of the aromatic nucleus did not occur. The reaction of perchlorylfluoride with aromatic trimethylstannyl compounds resulted in the formation of trimethyltin fluoride and the respective destannylated aromatics in variable yields.     

Electrochemical Amination in the System Ti(IV)–NH2OH–C6H6: The Efficiency of the Process in a Sulfuric Acid Solution Containing an Organic Solvent

Electrolysis of the system Ti(IV)–NH₂OH–C₆H₆ in an 11 M H₂SO₄ solution shows that using an organic solvent (acetic acid, acetonitrile) during cathodically initiated amination of aromatic substrates permits the production of aromatic amines with the overall yield by hydroxylamine reaching 91%. Due to a chain mechanism of radical substitution, the benzene amination in electrolytes containing 5 M CH₃COOH and 5.5 M CH₃CN terminates largely upon consuming 70–75 and 50–55% of the charge required theoretically for a one-electron process. The maximum efficiency of electrochemical amination is observed at low hydroxylamine conversions and the overall current efficiency for mono- and disubstituted products of the benzene amination may exceed in these conditions 750%.     

Reactions of 5-dialkylamino-1,2,3-thiadiazole-4-carbaldehydes with amines as a method for the synthesis of 1,2,3-triazole-4-carbothioamides

A method for the synthesis of previously inaccessible 5-dialkylamino-substituted 1,2,3-thiadiazole-4-carbaldehydes was developed. Ring transformation in these compounds induced by primary aliphatic and aromatic amines, hydroxylamines, and N-substituted hydrazines resulted in the synthesis of a broad range of 1,2,3-triazole-4-carbothioamide.