Formation of Tertiary 3-Nitro Allylic Alcohol by Condensation of 2-Chloroiso- butyrophenone with Nitromethanide Anion: Estimation of Gibbs Free Enthalpies of Reaction in Solution for the Reaction Mechanism [1]

Summary. The reaction of 2-chloroisobutyrophenones and nitromethanide anion gives stereoselectively (E)-3-nitro allylic alcohols. The Gibbs free enthalpies of reaction in DMSO for carbanion addition, epoxide formation, and rearrangement to 3-nitro allylic alcohol, as elementary steps for the reaction, were estimated from corresponding neutral gas reactions and using a thermodynamical approach to the transfer of gaseous compounds to DMSO. A criterion for assigning the sign of affinity of liquid compounds to DMSO was developed on the basis of the Gibbs enthalpies of liquefaction. The information obtained on reaction rate and thermodynamic viability of the steps indicates that carbanion addition is the rate-determining step.In memory of Prof. Dr. M. Ballester, deceased on April 6, 2005     

LiBF4: a mild and novel reagent for the OH insertion reactions of α-diazoketones

Lithium tetrafluoroborate (10 mol%) is found to catalyze efficiently the OH insertion reactions of α-diazoketones with various alcohols including benzylic, allylic, propargylic and cyclopropyl carbinols to produce the corresponding α-alkoxy ketones in excellent yields with high selectivity. A solution of 10 mol% of LiBF₄ in acetonitrile provides a convenient reaction medium to carry out the OH insertion reactions under mild and neutral conditions.     

Chemoselective synthesis of multiple epoxy-bridged tetrahydropyranone ring systems

Bis- as well as tris-tetrahydropyranone ring systems were obtained via multiple tandem cyclization-1,3-dipolar cycloaddition reactions of α-diazo ketones with ketone as well as aldehyde functional groups in a chemoselective manner.     

A novel deacylation during the amination of trifluoromethyl β-dicarbonyl compounds

Starting from trifluoromethyl β-dicarbonyl compounds, a rare loss of CF₃CO was observed in the amination reactions performed under heterogeneous conditions using NsONHCO₂Et as the aminating agent and CaO or NaH as the base, while corresponding nonfluorinated β-dicarbonyl compounds under analogous conditions give non deacylated aminated compounds. This reaction can facilitate a direct synthesis of N-substituted α-amino esters or α-amino ketones.     

Effective synthesis of 5-aryl-3-ethylidene-3H-pyrrol-2-ones

Substituted 5-aryl-3-ethylidene-3H-pyrrol-2-ones were synthesized by the reaction of the corresponding 4-aryl-4-oxobutanoic acids with ketones in the presence of aminating agents. The conditions of this reaction were developed with the use of both the conventional condensation technique and microwave activation. The structures of the reaction products were con-firmed by elemental analysis, IR spectroscopy, and ¹H NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 693–696, April, 2006.     

手性试剂TMPEA用于手性酮对映体纯度测定的研究

β-三氟甲基-β甲氧基β-苯基乙胺（TMPEA）是含氨基功能团的手性试剂[1]．由于胺可将按酸转变成酸胺，该试剂已成功地用于手性有机酸对映体的纯度测定[2]．考虑到胺同样可将醛酮转变成亚胺，本文进一步探讨了TMPEA用于手性醒酮对映体纯度测定的可行性．用R－（－）－TMPEA及dl－TMPAE分别与下列4种手性酮反应，制备相应的非对映异构亚胶：比较光活亚胺及相应的非对映异构体混合物亚腔的NMR谱，可确定各组非对映异构亚胺‘HNMR位移差（以OCH为探针基团）和’‘FNMR的位移差（以CF为探针基团）（表1）．TablelCheffiicalshif…     

Trace analysis of volatile polar organics by direct aqueous injection gas chromatography

Summary Procedures for the quantitative analysis of industrial effluents which involve concentration by solvent extraction or the purge-and-trap method are time-consuming, labor-intensive, and prone to error. Direct aqueous injection gas chromatography using an electron-capture detector for the analysis of volatile halocarbons at the ppb level is in routine use in many laboratories. We now discuss the development of a similar protocol for the analysis of volatile polar organics such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and tretrahydrofuran using a flame-ionization detector.     

Effect of 4f-shell excitation of Eu(fod)3 on its complex formation with alicyclic ketones

The complex formation of alicyclic ketones, viz., camphor, cyclohexanone, menthone, and cytisine, with the Eu(fod)₃ chelate (fod is 7,7-dimethyl-1,1,1,2,2,3,3-heptafluorooctane-4,5-dione) in the ground and excited states was studied by chemiluminescence and kinetic luminescence spectroscopy, respectively. The stability constants and thermodynamic parameters of complex formation were determined. An increase in the stability of the electron-excited complexes [Eu(fod)₃*·Ketone] is explained by the enhancement of the acceptor ability of the Eu³⁺ chelate due to an increase in the fraction of the covalent component caused by the involvement of 4f-orbitals. The results obtained give direct evidence for the effect of the 4f-shell excitation of Eu(fod)₃ on complex formation due to the involvement of f-electrons in the chemical bonds.     

Synthesis of β-amino carbonyl compounds via a Zn(OTf)2-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds

A Zn(OTf)₂-catalyzed cascade reaction of anilines with aromatic aldehydes and carbonyl compounds was described. This one-pot three-component reaction afforded the corresponding β-amino carbonyl compounds, β-amino esters, and β-amino ketones in good to excellent yields. The reaction was also applied for the liquid-phase synthesis of β-amino carbonyl compound library using PEG as a support.     

Gas chromatography-mass spectrometry coupled with pseudo-Sadtler retention indices, for the identification of components in the essential oil of Curcuma longa L.

Gas chromatography-mass spectrometry was applied to the cyclohexane extract of Curcuma longa L. The chromatographic conditions generated retention indices very close i.e., greater than 99.9%, to those reported for structures in the Sadtler Standard Gas Chromatography Retention Index Library. In addition to the extensively reported sesquiterpene ketones, this essential oil extract contained a series of saturated and unsaturated fatty acids. Wiley mass spectra library matching for the free fatty acids, their trimethylsilyl esters and methyl esters narrowed their identity down to a few candidates. Combining this information with the retention indices of the fatty acid methyl esters in the Sadtler library allowed the identification of some of the double bond positions.