Three-component cyclization of hydroxylamino-substituted quinoline with reactive methylene compounds and formaldehyde: new method for the synthesis of 7-(isoxazolidin-2-yl)-6-fluoroquinolones

A one-step procedure was developed for the synthesis of new 6-fluoro-7-(isoxazolidin-2-yl)-4-oxo-1,4-dihydroquinolines. The procedure is based on the 1,3-dipolar cycloaddition of the azomethine oxide and 1,1-disubstituted alkenes, which are generated in situ from 6-fluoro-7-hydroxylamino-4-oxo-1,4-dihydroquinoline-3-carboxylic acid and CH-active compounds (dialkyl malonates, ethyl acetoacetate), respectively, in the presence of formaldehyde at 100—120 °C.     

Synthesis of Cholesteryl Esters of Heterocyclic Analogs of Cinnamic Acid and Hetaroyloxycinnamic Acids by the Wittig Reaction

The reaction of cholesteryl triphenylphosphonioacetate chloride with heterocyclic aldehydes and hetaroyloxyarenecarbaldehydes in the presence of base gave the corresponding cholesteryl esters of substituted propenoic acids possessing liquid crystal properties.     

Reaction of dibenzylphosphine oxide with α,β-unsaturated O-methyloximes

The reaction of dibenzylphosphine oxide with O-methyloximes of some w0557276558/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">,w0557276558/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-unsaturated ketones results in the phosphorylation at the w0557276558/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of w0557276558/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">,w0557276558/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-unsaturated aldehydes affords aminodihydrophosphole oxides.     

The Comparison of the Orientation of Sodium 3-Hydroxy-2-Naphthalenecarboxylate in the Cavity of β-Cyclodextrin and Heptakis-(2,3,6-Tri-O-Methyl)-β-Cyclodextrin

Conformational analysis of inclusion complexes of sodium 3-hydroxy-2-naphthalenecarboxylate with w8k080n5454487v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin and heptakis-(2,3,6-tri-o-methyl)-w8k080n5454487v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin in D₂O was investigated by 1D and 2D ¹HNMR measurements. The results show that part of the naphthyl group of sodium 3-hydroxy-2-naphthalenecarboxylate is situated in the 2,3-OH side of the w8k080n5454487v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin cavity asymmetrically while the whole naphthyl group is included in the heptakis-(2,3,6-tri-o-methyl)-w8k080n5454487v2/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin cavity with the caboxylate and hydroxy group close to the 6-OCH₃ group.     

Gas chromatographic and IR spectroscopic characteristics of tri- and tetramethylcyclohexenyl butenyl ketones

Infrared spectroscopic characteristics and gas chromatographic retention indices of tri- and tetramethylcyclohexenyl butenyl ketones were determined at different temperatures of analysis. Thermodynamic characteristics of sorption on the apolar stationary phase were calculated. The sorption characteristics of tri- and tetramethylcyclohexenyl butenyl ketones show that under conditions of capillary gas chromatography these compounds are retained due to the dispersive energy. It was shown by FTIR spectroscopy that the formation of conjugation systems of double bonds is responsible for the higher retention of the w05x44128gv97637/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-isomers compared with that of the w05x44128gv97637/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-isomers. The shortening of the distance between the carbonyl and trimethylcyclohexenyl groups was found to be accompanied by a decrease in the retention of the isomeric compounds.     

Inclusion of Polyphenol Oxidase Substrates in β-Cyclodextrin: A 1 H-NMR Study

A ¹H-NMR study of the interactionsbetween w8k4783416/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (w8k4783416/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD) and included phenolic molecules (chloragenic acid and caffeic acid ) in aqueous medium is reported. The results confirm that inclusion occurs. Data analysis by the continuous variation method shows that all the complexes have 1 : 1 stoichiometries. Values for the apparent association constants of the inclusion compounds are estimated and compared with previously reported values.     

Analysis of nitro-PAHs in diesel exhaust particulate extracts with multicolumn HPLC

Summary A method is described for the determination of nitrated polynuclear aromatic hydrocarbons (nitro-PAHs), in particular 1-nitropyrene, in diesel particulate extracts. The method employs a multidimensional HPLC (column switching) technique with final on-line peak identification by UV-VIS spectral comparison with standards. To achieve exceptional chromatographic selectivity for nitro-PAHs, a new pyrene butyric acid amide phase has been prepared which is capable of forming donor-acceptor complexes with them. With this technique it is possible to confirm the presence of 1-nitropyrene in the range 3–100 ng/mg on filter-collected diesel soot. Its utility was demonstrated with diesel exhaust extracts spiked with varying levels of 1-nitropyrene and proved to be highly selective.Parts of this work have been presented at the w6w4t8/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">15th International Symposium on Chromatographyw6w4t8/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0">, Nürnberg, October 1984.Dedicated to Prof. J. F. K. Huber at the occasion of his 60th birthday.     

Synthesis and ozonization of (+)-4α-(1-trimethylsilyloxyethen-1-yl)-2-carene

(+)-4w3/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-(1-Trimethylsilyloxyethen-1-yl)-2-carene was synthesized, and the products of its ozonization were identified.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1984–1987, October, 1995.     

Application of solvent extraction and synchronous spectrofluorimetry to the determination of the formation constant for a 1:1 complex of carbazole withβ-cyclodextrin in water-dimethyl sulfoxide medium

Extraction of carbazole in heptane was performed at 25±1°C with an aqueous dimethyl sulfoxide (DMSO) medium containing w41pr63p0g110850/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (w41pr63p0g110850/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CD) at consecutive concentrations in the range of 0–10 mM. The fluorescence intensity of carbazole remaining in the heptane phase was measured by synchronous scanning fluorimetry. The apparent formation constant (K _f) for a 1:1 carbazole: w41pr63p0g110850/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CD inclusion complex in water-DMSO medium was determined by using a linear plot of the distribution ratio calculated from the fluorescence intensities vs. the w41pr63p0g110850/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD concentration. The values thus obtained ranged from 477 M^–1 in a 10% v/v DMSO medium to 12.1 M^–1 in a 60% v/v medium. Good linear relationships were observed between logK _f and the DMSO concentration ([DMSO]), and also between logK _f and the logarithm of the distribution coefficient (K _d) for carbazole. The formation constant in 100% water was estimated to be approximately 1.0×10³ M^–1 on the basis of the logK _f vs. [DMSO] and the logK _f vs. logK _d correlations.     

Photochemically induced fluorescence investigation of aβ-cyclodextrin: Azure A inclusion complex and determination of analytical parameters

The photooxidation of Azure A and fluorescence properties of Azure A and its photoproduct have been investigated in aqueous media and in the presence ofw330h5325n6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (w330h5325n6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD). The fluorescence intensity of the complex formed between the photoproduct and w330h5325n6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD was found to be three times higher than that of the uncomplexed Azure A photoproduct. A complex formation constant of 110±40 M^–1 was calculated using the Benesi-Hildebrand treatment of the fluorescence emission data. Although the stoichiometry of the Azure A photoproduct: w330h5325n6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD complex was found to be 1: 1, it seems that the Azure A structure is only partially included. Calibration graphs were plotted for the free Azure A photoproduct and the photogenerated product included in w330h5325n6/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CD. The analytical parameters and quantification limits were determined.