Ptychanolide, a sesquiterpenoid with a new type skeleton from the liverwort ptychanthus striatus (lehm. et lindenb.) nees

The structure of ptychanolide, isolated from the liverwort Ptychanthus striatus, has been determined by spectroscopic analysis and chemical transformation.     

On the single-site spin fluctuation theory for finite temperature magnetism

Some alternative schemes in the static functional-integral method combined with the alloy-analogy approximation are discussed. It is shown that the four-field method employed by Hubbard yields formally the same self-consistency equations as the two-field method used by Hasegawa for the paramagnetic state within the single-site coherent potential approximation.     

Intensified copper signal observed in the osmium-fixed cell of P. ochro-chloron by X-ray microanalysis

In a study of the metal distribution in a heavy metal tolerant fungus by means of X-ray microanalysis, the intensities of copper X-rays in a semi-thin section specimen of the cell cultivated in high copper concentration medium were found to be different between various fixation methods: glutaraldehyde fixation, glutaraldehyde-osmium vapor fixation and glutaraldehyde-osmium solution fixation. The copper content in the cell samples and the used fixative after the fixations were determined by atomic absorption spectrometry. After the fixations, the cell samples had approximately the same copper content. A copper signal was always detected together with an osmium signal. It was suggested that Kα X-ray emission of copper might be increased by Lβ₁ X-ray and the atomic number effect of osmium.     

Novel thermostable polymers from bis-o-aminophenylbenzimidazoles and aromatic tetracarboxylic dianhydrides

Novel aromatic hetero polymers, polybenzoylenebenzimidazoquinazolines, were prepared. These polymers were synthesized by the polymerization of bis-o-aminophenylbenzimidazoles with aromatic tetracarboxylic dianhydrides in organic solvents, followed by cyclocondensation of the polyamic acids in polyphosphoric acid. In the resulting polymers the o-phenylenediamine component behaved trifuntionally and the connecting groups were tricyclic fused rings that contained seven-membered rings. These polymers some of which has a ladder-type structure, exhibited excellent thermal properties.     

Collision and magnetic field effects on time-resolved fluorescence of D2CO excited by a N2 laser

Time-resolved fluorescence spectra of D₂CO were measured as a funtion of sample pressure. The result indicates the occurence of rotational and vibrational relaxation between excited states. The Magnetic field effect on fluorescence from D₂CO excited by a N₂ laser depends on the nature of the vibronic levels.     

The matrix effect on stereoselectivity of olefin cyclopropanation by arylcarbene

Temperature studies of additon of phenylcarbene to styrene showed that stereoselectivity changed rather dramatically as the reaction phase changed.     

A palladium catalyzed conversion of halohydrins to ketones

Pd(OAc)₂ combined with P(o-Tol)₃ catalyzes the conversion of halohydrins to ketones in the presence of K₂CO₃. Various halohydrins, which are easily available from olefins, can be converted to ketones in high yields.     

Structure of thalictoside

Thalictoside (I), a novel glycoside containing a nitro group, has been isolated from Thalictrum aquilegifolium and the structure has been established by chemical transformations, spectral analysis and synthesis.