New proline analogues for organocatalysis

This paper describes an anomalous behaviour of the Sharpless dihydroxylation of a terminal olefin. The synthesis of a new chiral pyrrolidine and its application as an organocatalyst in the Michael addition of cyclohexanone into nitrostyrenes are described.     

Studies on pyrrolidinones: Some attempts to improve the synthesis of methyl n‐(3,4,4′,5‐tetramethoxybenzhydryl)pyroglutamate (hei 81) by using n‐acyl iminium salts methodologies

Some ways to use the N‐acyl iminium salt methodologies to synthesize a new inhibitor of tubulin polymerization, methyl N‐(3,4,4′,5‐tetramethoxybenzhydryl)pyroglutamate (HEI 81) were studied. The most interesting reactions utilize a new pyroglutamic lactone (3‐(3,4,5‐trimethoxyphenyl)dihydropy‐rrolo[1,2‐c]oxazole‐1,5‐dione).     

An heuristic derivation for the rate of change of the orbital period of a relativistic binary system

We present an heuristic derivation for the rate of change of the orbital period (at the post-newtonian level) of a semi-relativistic binary as due to emission of gravitational radiation. We assume a couple of physically reasonable hypotheses taking into account the literature on the subject.     

Li ion mobility in TeO2---LiO0.5---LiX (X = F, Cl) glasses determined by Li NMR and impedance spectroscopy

NMR and impedance spectroscopies have been used to study the Li⁺ ion mobility in the TeO₂---LiO_0.5---LiX (X = F, Cl) glasses. Activation energies determined from the temperature dependence of dc conductivity data decrease as the lithium or halogen content increases. Activation energies deduced from the analysis of the ac conductivity data in the complex modulus formalism and corresponding to the true one-particle energy barrier of ionic motion according to the coupling model, have been compared to those deduced from NMR data (T₁⁻¹ relaxation time): a good agreement is obtained. Finally, the influence of the glass composition and ion distribution on Li⁺ ion mobility has been discussed.     

A convenient synthesis of spherical cryptands by a quaternization-dealkylation procedure.

The construction of spherical cryptands has been accomplished from $\text{bis}$-diamines by a stepwise quaternization-demethylation sequence. Cryptands with diverse bridges can be easily prepared by this procedure.