Synthesis, including asymmetric synthesis, of 1-substituted cyclopentenes from cyclobutanones with one-carbon ring-expansion by 1,2-carbon-carbon insertion of magnesium carbenoids

Treatment of 1-chlorovinyl p-tolyl sulfoxides, which were derived from cyclobutanones and chloromethyl p-tolyl sulfoxide, with lithium enolate of tert-butyl carboxylates, amides, lithium α-sulfonyl carbanions, and lithium α-carbanion of acetonitrile gave adducts in high to quantitative yields. The adducts were treated with Grignard regents, such as i-PrMgCl and EtMgCl in toluene to afford 1-substituted cyclopentenes in good to high yields with one-carbon ring-expansion via 1,2-carbon-carbon (1,2-CC) insertion reaction of the generated magnesium carbenoid intermediates. The magnesium carbenoid 1,2-CC insertion was found to be highly stereospecific. When optically pure chloromethyl p-tolyl sulfoxide was used in this procedure, optically active 1-substituted cyclopentenes were obtained in high optical purity.     

Synthesis,Crystal Structures,and Properties of 6,12‐Diaryl‐Substituted Indeno[1,2‐b]fluorenes

Fused polycyclic indeno[1,2‐b]fluorene derivatives with aryl substituents at the 6,12‐positions have been prepared as a potential antiaromatic 20π electronic system. They showed strong absorptions in the visible region and amphoteric redox properties. The quinoid‐type molecular structures were revealed by X‐ray crystal‐structure analysis, which indicated that the bond lengths of the quinoid unit depend on the aryl substituents. Whereas nucleus‐independent chemical shift NICS(1) calculations indicate the antiaromatic nature of the s‐indacene core, they have higher stability than substituted acene derivatives. The derivatives with difluorophenyl or anthryl groups were stable in solution. Vapor‐deposited thin films showed ambipolar carrier transportation in the field‐effect transistor devices.     

The first example of regiospecific magnesium carbenoid 1,3-CH insertion: its mechanism and stereochemistry

Addition reaction of two geometrical isomers of 1-chlorovinyl p-tolyl sulfoxides, derived from unsymmetrical ketones and chloromethyl p-tolyl sulfoxide, with lithium enolate of tert-butyl acetate gave single isomers of the adduct, respectively. Treatment of each diastereomer with i-PrMgCl resulted in the formation of magnesium carbenoids. Highly regiospecific 1,3-CH insertion reaction was found to take place from the magnesium carbenoids to afford cyclopropanes in high yields. Stereochemistry of the adducts, reaction mechanism, and origin of the regiospecificity are discussed.     

Intermittent transport associated with the geodesic acoustic mode near the critical gradient regime

Turbulent transport near the critical gradient in toroidal plasmas is studied based on global Landau-fluid simulations and an extended predator-prey theoretical model of ion temperature gradient turbulence. A new type of intermittent transport associated with the emission and propagation of a geodesic acoustic mode (GAM) is found near the critical gradient regime, which is referred to as GAM intermittency. The intermittency is characterized by new time scales of trigger, damping, and recursion due to GAM damping. During the recursion of intermittent bursts, stationary zonal flow increases with a slow time scale due to the accumulation of undamped residues and eventually quenches the turbulence, suggesting that a nonlinear upshift of the critical gradient, i.e., Dimits shift, is established through such a dynamical process.     

First results from KamLAND: evidence for reactor antineutrino disappearance

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.     

Preparation, structure, and properties of metal nanocomposites in lithium niobate

Crystals of lithium niobate LiNbO₃ are implanted with 60-keV Cu^? ions at different ion fluxes to a fluence of 2 × 10¹⁷ ions/cm². The structure and the linear and nonlinear optical properties of the implanted layers are investigated. The optical transmission and ion-induced photon spectra of the LiNbO₃ crystals are measured in the course of implantation. It is revealed that the implantation brings about the formation of complex nanocomposites consisting of metallic copper nanoparticles and nanodomains of the matrix. The distributions of nanoparticles and nanodomains in the implanted layers do not correlate with each other. It is shown that the variations in the linear and nonlinear optical absorption of the nanocomposites are predominantly determined by the changes in the chemical composition and the structure of the matrix.     

Boson description of nuclear collective motion

Nuclear system with octupole-octupole interaction is studied by means of the boson expansion method. Expressions of the fourth-order collective Hamiltonian and third-order octupole moment operator are derived. For¹¹²Cd and¹⁴⁸Sm, characteristics of octupole vibrational spectra are discussed in comparison with the quadrupole vibration.     

Boson description of nuclear collective motion. I

As the first part of the series on the application of the boson expansion method to the nuclear collective motion, the method of Kishimoto and Tamura is illustrated by taking a simple case of boson expansion up to second order. By taking into account the effect of particle channel by the projection technique, the lowest mode is shown to have the same property as the RPA phonon.