Water-soluble constituents of cumin: monoterpenoid glucosides

From the water-soluble portion of the methanol extract of cumin (fruit of Cuminum cyminum L.), which has been used as a spice and medicine since antiquity, sixteen monoterpenoid glucosides, including twelve new compounds, were isolated. Their structures were clarified by spectral investigation.     

Electron scattering from tetrafluoroethylene

We report experimental results for electron scattering from tetrafluoroethylene, C2F4, obtained from measurements in two laboratories. An extensive set of differential, integral, and momentum transfer cross sections is provided for elastic scattering for incident electron energies from 1 to 100 eV and inelastic (vibrational excitation) scattering for incident electron energies at 3, 6, 7.5, 8, and 15 eV, and for scattering angles ranging from 10 degrees to 130 degrees. To highlight the role of intermediate negative ions (resonances) in the scattering process we have also measured excitation functions for elastic scattering and vibrational excitation of the ground electronic state of C2F4 for incident energies between 1.5 and 20 eV. Our results are compared with recent theoretical calculations and a limited number of other experimental results.     

First asymmetric total syntheses of cernuane-type Lycopodium alkaloids, cernuine, and cermizine D

The first total syntheses of two cernuane-type Lycopodium alkaloids, (-)-cernuine and (+)-cermizine D, were accomplished starting from (+)-citronellal. The syntheses involved organocatalytic alpha-amination to afford oxazolidinone, which is used for diastereoselective allylation, and asymmetric transfer aminoallylation followed by stereoselective construction of an aminal moiety as key steps.     

GaCl3- and TiCl4-catalyzed insertion of isocyanides into a C-S bond of dithioacetals

The insertion reaction of isocyanide into a C-S bond of dithioacetals is catalyzed by GaCl3 or TiCl4 to afford thioimidates containing an alpha-alkylthio group. Balanced thiophilicity of these Lewis acids is critical for efficient catalysis.     

Violation of the Franck-Condon principle due to recoil effects in high energy molecular core-level photoionization

Carbon 1s photoelectron spectra of methane are measured over a photon energy range between 480 eV and 1200 eV. Additional components appear between the individual symmetric stretching vibrational components and are attributed to the excitations of asymmetric stretching and bending vibrations due to recoil of the high-energy photoelectron emission. This recoil effect is the evidence for the violation of the Franck-Condon principle which states that neither the positions nor the momenta of the nuclei change during the ionization event.     

Efficient and stereoselective installation of isoquinoline: formal total synthesis of cortistatin A

The highly stereoselective attachment of isoquinoline onto the steroidal framework of cortistatin A has been achieved. Our strategy features a Ce-mediated nucleophilic addition of an isoquinoline unit to the sterically congested ketone followed by formation of the phenyl thiocarbamate, and subsequent stereoselective radical reduction. The new method results in a formal total synthesis of cortistatin A.     

Ten new fawcettimine-related alkaloids from three species of Lycopodium

Ten new fawcettimine-related alkaloids, i.e., lycopoclavamines, lycoposquarrosamine-A, and other hydroxylated fawcettimine derivatives, were isolated from three species of Lycopodium (Lycopodium clavatum, Lycopodium serratum, and Lycopodium squarrosum). The structures of the new alkaloids were elucidated by spectroscopic methods and chemical correlation.     

Optical control and mode selective excitation of coherent phonons in YBa2Cu3O7−δ

Femtosecond time-resolved reflectivity measurement is performed on Y Ba₂Cu₃O_7?δ films. Coherent phonons of both the Ba–O and Cu–O modes are observed at frequencies of 3.4 and 4.3 THz, respectively. Amplitudes of both Ba–O and Cu–O modes are optically manipulated by using a pair of femtosecond pulses, the separation time of which is controlled. Coherent phonons of the Ba–O and Cu–O modes are completely suppressed at the double-pulse separation times of 135.0 and 108.5 fs and those amplitudes are enhanced at 270 and 217 fs, respectively.     

Dynamical suppression of dephasing for Markov processes

It is shown that the dephasing of a qubit caused by a Markov process can be suppressed by a successive application of π-pulses if two-time conditional probability of the stochastic variable depends only on the time-difference. The several types of the π-pulse sequence are compared in the case of the two-state jump Markov process.