Carbonatation de divers organocuivreux

Various saturated, α- or β- ethylenic, or arylic organocopper compounds have been carboxylated under conditions very similar to those used with vinyl-copper compounds. We discuss the positive influence of a catalytic amount of triethyl phosphite, whereas the use of a stoichiometric quantity, or the presence of metallic halides, decreases the yields of insertion. Carboxylic acids are obtained with excellent yields.     

Additions radicalaires du tétrahydrothiophène à des dérivés éthyléniques: Préparation de tétrahydrothiophènes substitués en 2

Di-t-butyl peroxide induces a free radical addition of tetrahydrothiophene to ethylenic compounds. The main products arise from an α-attack of the substrate. This reaction seems to be an interesting synthesis of these heterocycles.     

Composés de solvatation des halogenures de mercure II avec quelques amines aliphatiques

Addition compounds of anhydrous mercury(II) halides were prepared with propylamine, isopropylamine, butylamine and isobutylamine. These solyates have the general formula HgX₂, 2RNH₂. A study of their thermal stability by TG and DTA methods has shown that some stable intermediates are produced in the course of decomposition. The standard enthalpies of formation have been determined by dissolution in acidic medium and the variation of enthalpy based on the evolution of the molecules of amine was determined by this way and by means of a differential enthalpic analyser. The interpretation of their infrared spectra is discussed.     

Molecular orbital studies on the conformation of GABA (γ-aminobutyric acid)

In distinction to Extended Hückel Theory which predicts as the most stable conformation of free zwitterionic GABA a totally extended form, PCILO and SCF ab initio studies show that the intrinsically preferred conformation of the isolated molecule is a highly folded one, resulting from strong interactions between the two charged ends. Computations are also carried out for hydrated GABA in the supermolecule approach allowing moreover for the flexibility of binding of some of the water molecules of the first hydration shell. They predict the coexistence in solution of a large number of conformations showing different degrees of folding (or extension), a result confirmed by recent NMR studies. This and a number of similar results show that we have to adapt our thinking on the role of conformations in pharmacological activity to this situation, which was frequently obscured by the more abundant results of X-ray crystallography yielding a single conformation.     

(1-Adamantanethio)pyridines and tetrahydropyridines from the reaction of 1-adamantanethiol with pyridine I-oxide in acetic anhydride

The reaction of pyridine 1-oxide with 1-adamantanethiol in acetic anhydride produced a mixture of 2- and 3-(1-adamantanethio)pyridines, 1-aeetyl-2-(1-adamantanethio)-3-hydroxy-4-acetoxy-1,2,3,4-telrahydropyridine and the corresponding 3-acetoxyderivative. Pure substances were separated by means of column chromatography on alumina. The tetrahydropyridines were identified by means of their proton magnetic and mass spectra. 4-(1-Adamantanethio)pyridine was synthesized from 4-chloropyridinc and 1-adamantanethiol. The three isomeric (1-adamantanethio)-pyridines were, each, cleaved by concentrated hydrochloric acid to give 1-chloroadamantane and the corresponding pyridinethiol.     

General theoretical study of the stepwise coupling methods:: Part I. Determination of the generalised valence force field in the n-order cases and the matrix polynomial expansion of the eigenvector method

In the n-order general cases the Eigenvector Method of Becher and Mattes is shown to have an equivalent form: The Matrix Polynomial Expansion Method which is much simpler for computational procedures and has none of the inconvenience of the previous stepwise coupling methods (e.g., the Fadini's methods, the Eigenvector Method and the Logarithmic Steps Method of Wendling and Mahmoudi). It is also shown that the Eigenvector Method and the Matrix Polynomial Expansion Method correspond to the “closest solution” to the complete uncoupled initial solution, thereby justifying the method and giving application limits.