Heterocycles from substituted amides. VI. A new carbostyril synthesis from alpha-substituted acetamides and the vilsmeier reagent

Reaction of tertiary α-substituted acetanilides with Vilsmeier reagent has been found to give 1,3-disubstituted-carbostyrils, 1. α-Chloro-N-(1-cyclohexen-1-yl) acetamides are similarly converted to tetrahydro carbostyrils 2 and 3. The method appears useful for the preparation of a variety of 1,3-substituted 2(1H) quinolinones. The scope and mechanism of the reaction has been investigated, with evidence presented to indicate the ring-closure proceeds via electrophilic attack of Vilsmeier reagent on intermediate chlorenamine.     

HPLC of 9-fluorenylmethylchloroformate-polyamine derivatives with fluorescence detection

Summary There are a number of reagents available for fluorescent labelling of primary amines. These include dansyl chloride, o-phthalaldehyde, fluorescamine, and a new reagent, 9-fluorenylmethylchloroformate (FMOC), reported recently. This paper describes a reversed-phase HPLC procedure for the separation and fluorescence detection of polyamines following pre-column derivatization with FMOC. The polyamines studied by this method include putrescine, cadaverine, spermidine, and spermine. Experiments were carried out to determine maximum fluorescence excitation and emission wavelengths, optimum reaction pH, linear ranges, and minimum detection limits for each of the polyamines. The HPLC method includes a gradient program which provides complete separation from serum hydrolysate components and specificity for the four polyamines with detection limits ranging from 2 to 9 pg. This procedure was applied to hydrolyzed serum samples.     

C2-symmetric bis(oxazolinato)lanthanide catalysts for enantioselective intramolecular hydroamination/cyclization

C(2)-symmetric bis(oxazolinato)lanthanide complexes of the type [(4R,5S)-Ph(2)Box]La[N(TMS)(2)](2), [(4S,5R)-Ar(2)Box]La[N(TMS)(2)](2), and [(4S)-Ph-5,5-Me(2)Box]La[N(TMS)(2)](2) (Box = 2,2'-bis(2-oxazoline)methylenyl; Ar = 4-tert-butylphenyl, 1-naphthyl; TMS = SiMe(3)) serve as precatalysts for the efficient enantioselective intramolecular hydroamination/cyclization of aminoalkenes and aminodienes. These new catalyst systems are conveniently generated in situ from the known metal precursors Ln[N(TMS)(2)](3) or Ln[CH(TMS)(2)](3) (Ln = La, Nd, Sm, Y, Lu) and 1.2 equiv of commercially available or readily prepared bis(oxazoline) ligands such as (4R,5S)-Ph(2)BoxH, (4S,5R)-Ar(2)BoxH, and (4S)-Ph-5,5-Me(2)BoxH. The X-ray crystal structure of [(4S)-(t)BuBox]Lu[CH(TMS)(2)](2) provides insight into the structure of the in situ generated precatalyst species. Lanthanides having the largest ionic radii exhibit the highest turnover frequencies as well as enantioselectivities. Reaction rates maximize near 1:1 BoxH:Ln ratio (ligand acceleration); however, increasing the ratio to 2:1 BoxH:Ln decreases the reaction rate, while affording enantiomeric excesses similar to the 1:1 BoxH:Ln case. A screening study of bis(oxazoline) ligands reveals that aryl stereodirecting groups at the oxazoline ring 4 position and additional substitution (geminal dimethyl or aryl) at the 5 position are crucial for high turnover frequencies and good enantioselectivities. The optimized precatalyst, in situ generated [(4R,5S)-Ph(2)Box]La[N(TMS)(2)](2), exhibits good rates and enantioselectivities, comparable to or greater than those achieved with chiral C(1)-symmetric organolanthanocene catalysts, even for poorly responsive substrates (up to 67% ee at 23 degrees C). Kinetic studies reveal that hydroamination rates are zero order in [amine substrate] and first order in [catalyst], implicating the same general mechanism for organolanthanide-catalyzed hydroamination/cyclizations (intramolecular turnover-limiting olefin insertion followed by the rapid protonolysis of an Ln-C bond by amine substrate) and implying that the active catalytic species is monomeric.     

Effects of digestion,chemical separation,and deposition on Po-210 quantitative analysis

The purpose of this work was to determine polonium losses from a variety of sample types (soil, cotton fiber, and air filter) due to digestion technique, chemical separation, and deposition method for alpha energy analysis. Results demonstrated that yields from a perchloric acid wet-ash (87 ± 5 %) were similar to that from a microwave digestion (100 ± 7 %), but both were greater than the dry-ash procedure (38 ± 5 %). The polonium was separated from an SRM soil using an AG1X8 ion exchange column and deposited on a Ag disk with a recovery of 83 ± 7 % of polonium-209 (Po-209). Deposition yields without chemical separation averaged 90 ± 5 % of Po-209. The polonium-210 content was successfully measured in the three matrix types and quantitated using alpha spectroscopy.     

微乳液的热力学性质 I: 芳烃类的侧链链长对微乳液热力学函数影响

本文研究以非离子型表面活性剂-正辛醇-水-芳烃类所组成的微乳液, 探讨醇从油相转移到界面相时的自由能变化, 以及温度对自由能的影响。计算出熵和焓的变化, 发现在实验范围内, 上述热力学函数的对数值与芳烃侧链的碳原子数(n)呈线性关系。这些关系式对微乳液的构成和稳定性的讨论是重要的, 还对几种芳烃异构体所构成的微乳液的热力学函数进行了实验和讨论。