Nucleophilic addition reaction of 2-trimethylsilyloxyfuran to N-gulosyl-C-alkoxymethylnitrones: synthetic approach to polyoxin C

[reaction: see text] The stereoselectivity of nucleophilic addition of 2-trimethylsilyloxyfuran to N-gulosyl-C-alkoxymethylnitrones was investigated. It was found that the selectivity was highly dependent on the bulkiness of the C-substituent of the nitrone. The major adducts were elaborated into the key intermediate of polyoxin C.     

Hypernuclear fine structure in (9)(lambda)Be

With a germanium detector array (Hyperball), we observed two gamma-ray peaks corresponding to the two transitions (5/2(+)-->1/2(+) and 3/2(+)-->1/2(+)) in the (9)(Lambda)Be hypernucleus which was produced by the 9Be(K-,pi(-)) reaction. The energies of the gamma rays are 3029 +/- 2 +/- 1 keV and 3060 +/- 2 +/- 1 keV. The energy difference was measured to be 31.4(+2.5)(-3.6) keV, which indicates a very small Lambda-spin-dependent spin-orbit force between a Lambda and a nucleon. This is the smallest level splitting by far ever measured in a hypernucleus.     

Conversion of quassinoids for enhancement of inhibitory effect against Epstein-Barr virus early antigen activation. Introduction of lipophilic side chain and esterification of diosphenol

Introduction of a senecioyl group into shinjulactones B and C, and esterification of the diosphenol moiety in brusatol and brucein A enhanced inhibitory effect against Epstein-Barr virus early antigen activation.     

Photochemistry of N-acylimino-isoquinolinium and -quinolinium betaines

The photochemical behavior of N-acyliminoisoquinolinium and -quinolinium betaines has been investigated. In contrast to pyridinium betaines, the principal course of reaction is the 1,2-migration of N-acylamino groups. Substituent effects as well as solvent effects are observed. The results are rationalized in terms of diaziridine intermediates.     

Selective absorption

Summary Some organic acids, alcohol and amine which have an asymmetric carbon atom were used for an investigation of asymmetric absorption on wool. Racemic mixture of hydratropic acid, mandelic acid andα-phenethylamine have shown the selective absorption on wool from their aqueous and alcoholic aqueous solutions and S-form of their diastereoisomers preferentially absorbed on wool. According to the results we obtained so far, it is concluded that the preferential absorption strongly depends on the configuration of the substance of which wool is composed.     

Phonon modes in mass-defect disordered alloy NiPt

The phonon dispersion relations of 00σT branch were measured for Ni₉₅Pt₅ and Ni₇₀Pt₃₀. The dispersion curves breaks up into two branches. Th general shape and its concentration dependence can be explained qualitatively by Taylor's coherent potential approximation theory.     

On the miscibility gap in liquid bismuth-bismuth tribromide system

We have determined the location of the miscibility gap in liquid Bi-BiBr₃ system in the concentration-temperature, x?T, plane from the measurement of the electrical conductivity. The measurements have been done in the concentration range between 30.5 and 92.5 mol.% Bi and in the temperature range between 300 and 600°C. It is found that the temperature dependence of the conductivity of the mixture changes near the retrograde solubility region.