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A unique 1,7-S- and Se-shift reaction under Pummerer reaction conditions of 4-alkenyl-3-sulfinyl- and seleninylpyrroles was described. The usual Pummerer reaction of 4-(alkenylaminomethyl)-3-phenylsulfinylpyrroles and a successive reaction with tetrabutylammonium hydroxide (TBAH) yielded either pyrrolo[3,2-c]azepines or N-pyrrol-3-ylmethyl-N-(4-hydroxy-3-sulfanylpropyl)-p-toluenesulfonamides (diols). Seleno-Pummerer reactions of 3-selanylmethylpyrroles also proceeded via in situ generation of selenoxides, followed by a treatment with TBAH.

Quantum Chemistry Literature Data Base (QCLDB, http://qcldb2.ims.ac.jp) is a database of those papers published after 1978 which treat only ab initio calculations of atomic and molecular electronic...

A protocol for the direct synthesis of azepines using a hafnium(III)-catalyzed [6 + 1] annulation of N-tethered ynenitriles with Reformatsky reagents is reported. A broad range of 3-amino-2,7-dihydro-1H-azepine-4-carboxylates 4aa-4he were obtained in high yields and with excellent functional group tolerance. The copper-mediated reactions of isolable Blaise intermediates (enamino esters 3), uniquely underwent 5-endo cyclization to afford the β-2,5-dihydropyrrolyl α,β-unsaturated esters 5aa-5fc, which exhibit anticancer activity.

4-Hydroxy-2-nonenal (HNE), a major racemic product of lipid peroxidation, reacts with histidine to form a stable HNE-histidine Michael addition-type adduct possessing three chiral centers in the cyclic hemiacetal structure. In the present study, we characterized configurational isomers of a HNE-N α-acetylhistidine adduct by NMR spectroscopy and by molecular orbital calculations. In addition, we raised monoclonal antibodies against (R)-HNE-histidine and (S)-HNE-histidine adducts, characterized their specificities, and examined in vivo localizations of each adduct under oxidative stress. To facilitate structural characterization of the configurational isomers of an HNE-histidine adduct, we prepared the (R)-HNE-histidine and (S)-HNE-histidine adducts by incubatingN α-acetylhistidine with each HNE enantiomer, both of which provided two peaks (Ra and Rb from (R)-HNE-histidine and Sa and Sb from (S)-HNE-histidine adducts) in reversed-phase high-performance liquid chromatography. The NMR analysis showed that each peak was a mixture of two diastereomers. In addition, the analysis of the nuclear Overhauser effect enabled the determination of configurations of the eight isomers. The relative amounts of these isomers in the NMR analysis correlated with the relative energies calculated by molecular orbital methods. On the other hand, using (R)-HNE-modified and (S)-HNE-modified keyhole limpet hemocyanins as the antigens, we raised the monoclonal antibodies, mAbR310 and mAbS412, which enantioselectively recognized the (R)-HNE-histidine and (S)-HNE-histidine adducts, respectively. Among the mixtures (Ra, Rb, Sa, and Sb) of diastereomers, mAbR310 showed the highest immunoreactivity to Rb (the mixture of 2R,4S,5R and 2S,4S,5R isomers), whereas mAbS412 preferentially recognized Sa (the mixture of 2R,4S,5S and 2S,4S,5S isomers). The presence of (R)-HNE and (S)-HNE epitopes in vivo was immunohistochemically examined in the kidney of rats exposed to the renal carcinogen, ferric nitrilotriacetate, by which nuclear and cytosolic stainings with mAbR310 and mAbS412, respectively, were detected.

The thermochemical stabilities of gas phase cluster ions C 2 H 5 +(Sol) n , s-C 3 H 7 +(Sol) n , and t-C 4 H 9 +(Sol) n (Sol = CO 2 and N 2 O) were determined using a pulsed electron beam high-pressure mass spectrometer. The stabilities and structures of those cluster ions were studied theoretically by density functional theory calculations. For the free C 2 H 5 + ion, not the classical but the nonclassical bridged form is likely to be the major component. B3LYP/6-311+G(2d,p) calculations showed that the classical structure is absent. In the clustering reaction of C 2 H 5 + with Sol, a hydrogen bond type loose complex of the nonclassical C 2 H 5 + with Sol is initially formed, which is followed by the intramolecular isomerization of C 2 H 5 + to the classical structure forming the stronger bond with Sol. Surprisingly small bond energies of 4-5 kcal/mol for s-C 3 H 7 +Sol and t-C 4 H 9 +Sol arise from the hyperconjugation effect of methyl groups.

The structure parameters around the Cu(I) ion in pyridine (PY), 4-methylpyridine (4MPY), 2-methylpyridine (2MPY), 2,6-dimethylpyridine (26DMPY), and acetonitrile (AN) were determined by the extended X-ray absorption fine structure (EXAFS) method. The solvation structures of the Cu(I) ion in PY, 4MPY, and AN are 4-coordinate tetrahedral with Cu-N bond lengths of 205, 205, and 200 pm, respectively. In the case of 2MPY and 26DMPY, the Cu(I) ion has a 3-coordinate triangular structure with a Cu-N bond length of 201 pm. Such a decrease in the coordination number was interpreted in terms of the bulkiness of the solvent molecules. In order to clarify the most stable solvation structure of the Cu(I) ion, we carried out ab initio molecular orbital calculations for the solvation system of [Cu(NCH)n]+ (n = 1 - 6 ) where the steric effect is negligible. The Gibbs free energy of solvation was the smallest in the case of n = 4 and the 4-coordinate tetrahedral solvation of the Cu(I) ion was theoretically evaluated as most stable. The enthalpy of solvation monotonously decreases with increasing n, while the entropy of solvation proportionally increases. Although a larger gain of enthalpy is observed for the octahedral structure rather than the tetrahedral one, the entropic loss for the former overcomes the enthalpic gain.

Structure parameters of solvated silver(I) ions in eight neat solvents were determined by extended X-ray absorption fine structure spectroscopy. The coordination geometry of the solvated silver(I) ion is four-coordinate tetrahedral at the Ag−O bond distances of 239 pm in trimethylphosphate, 239 pm in N,N-dimethylformamide, 238 pm in 1,1,3,3-tetramethylurea, and 238 pm in dimethyl sulfoxide as oxygen-donating solvents, and at the Ag−N bond distances of 229 pm in acetonitrile, 230 pm in 2-methylpyridine, 229 pm in n-propylamine, and 231 pm in ethylenediamine as nitrogen-donating solvents. According to our present ab initio molecular orbital calculations concerning the structure of the silver(I) ion bound by n molecules of hydrogen cyanide (n = 1−6) and acetonitrile (n = 1−5) in the gas phase, the maximal stabilization for the solvation is observed at n = 4. The results of the theoretical calculations in the gas phase are consistent with the experimental observations in solution.

4-Hydroxy-2-nonenal (HNE), a major racemic product of lipid peroxidation, reacts with histidine to form a stable HNE-histidine Michael addition-type adduct possessing three chiral centers in the cyclic hemiacetal structure. In the present study, we characterized configurational isomers of a HNE-N(alpha)-acetylhistidine adduct by NMR spectroscopy and by molecular orbital calculations. In addition, we raised monoclonal antibodies against (R)-HNE-histidine and (S)-HNE-histidine adducts, characterized their specificities, and examined in vivo localizations of each adduct under oxidative stress. To facilitate structural characterization of the configurational isomers of an HNE-histidine adduct, we prepared the (R)-HNE-histidine and (S)-HNE-histidine adducts by incubating N(alpha)-acetylhistidine with each HNE enantiomer, both of which provided two peaks (Ra and Rb from (R)-HNE-histidine and Sa and Sb from (S)-HNE-histidine adducts) in reversed-phase high-performance liquid chromatography. The NMR analysis showed that each peak was a mixture of two diastereomers. In addition, the analysis of the nuclear Overhauser effect enabled the determination of configurations of the eight isomers. The relative amounts of these isomers in the NMR analysis correlated with the relative energies calculated by molecular orbital methods. On the other hand, using (R)-HNE-modified and (S)-HNE-modified keyhole limpet hemocyanins as the antigens, we raised the monoclonal antibodies, mAbR310 and mAbS412, which enantioselectively recognized the (R)-HNE-histidine and (S)-HNE-histidine adducts, respectively. Among the mixtures (Ra, Rb, Sa, and Sb) of diastereomers, mAbR310 showed the highest immunoreactivity to Rb (the mixture of 2R,4S,5R and 2S,4S,5R isomers), whereas mAbS412 preferentially recognized Sa (the mixture of 2R,4S,5S and 2S,4S,5S isomers). The presence of (R)-HNE and (S)-HNE epitopes in vivo was immunohistochemically examined in the kidney of rats exposed to the renal carcinogen, ferric nitrilotriacetate, by which nuclear and cytosolic stainings with mAbR310 and mAbS412, respectively, were detected.

Hydrogenated nanostructured graphite has been reported to exhibit a characteristic peak at around 600–800 K in thermal desorption spectroscopy (TDS). The origin of this peak is still controversial. We have reexamined it based on a combination Fourier transform infrared (FT-IR), electron diffraction, and electron energy-loss spectroscopy (EELS) study. The FT-IR spectrum of HNG exhibited an unknown broad absorption band at very low frequencies around 660 cm^{−1}, which almost disappeared by annealing up to 800 K. Electron diffraction as well as plasmon peaks in EELS detected unusual shrinkage and subsequent expansion of the graphene interlayer distance by hydrogen incorporation and desorption with annealing, which were well correlated with the change in intensity of the 660 cm^{−1} IR band. An energetically stable configuration was found by theoretical model calculations based on GAUSSIAN03. All the present results are consistent with our previous studies, which suggested that hydrogen is loosely trapped between graphene layers.