Louis Giral

Reactivite des carbanions benzyliques : VIII. Etude de la structure d'alkyl-9 lithio-10 dihydro-9,10 anthracenes par rmn du proton et spectrometrie d'absorption electronique; influence du substituant, du solvant et de la temperature

Abstract The structure of the 9,10-dihydroanthracenyl anion and of a series of 9-alkyl-10-lithio-9-10-dihydroanthracenes (9-R-10-LiDHA, I–V where R = H, Me, Et, i-Pr, t-Bu) was studied in solution by electronic absortion spectrometry and proton magnetic resonance. Our electronic absorption results, in addition to those of other authors, show that the contact ion pairs (c.i.p.) have an absorption at λ max }- 400 nm (I–III) and 415 nm (V) whereas the loose ion pairs (l.i.p.) absorb at λmax}- 450 nm (I–V). In the NMR the chemical shift of the proton para with respect to the carbanionic center was examined as a function of solvent (THF, THF/HMPA, and in some cases ether or pure HMPA) and temperature (+20 to −40°C). The para proton is shielded significantly with regard to the aromatic protons of the hydrocarbon (Δδ(H para ) ca. 1–1.7 ppm). The weakest shielding was observed in ether, in agreement with the existence of c.i.p. The largest shielding (THF/HMPA or pure HMPA) is in connection with the presence of l.i.p. where the negative charge is less localised at position 10. Moreover, in the same solvent, and at the same temperature, Δδ(H para ) was observed to increase with the substituent bulk, up to the point that there are only l.i.p. present. As found previously (namely for the fluorenyl anion) the l.i.p./c.i.p. ratio increases when temperature decreases. The results of this structural study allow to rationalize the protonation stereochemistry of 9-alkyl-10-lithio-9,10-dihydroanthracenes in the above-mentioned solvents.

New radical-cation salts containing an unsymmetrically substituted TTF or TSF type π -donor. Synthesis and characterization

Abstract A number of unsymmetrically substituted tetraheterofulvalenes have been prepared. Their half wave potentials have been measured by cyclic voltammetry and compared with that of TTF. Their perchlorate and hexafluorophosphate salts have been electrochemically synthesized and their electrical properties studied. Some structural data are also given.

Nouveaux sels d'ions radicaux dans la famille de “TTF”.

Abstract We describe the synthesis of a new series of radical cation salts : (TTTF)2X : X = BF4, ClO4, PF6, AsF6, NO3, Br. The electrical properties and the preliminary structural data are given, specially for (TTTF)2BF4.

Some Observations About Polysilane Synthesis

Abstract Three polysilanes have been synthesized by Wurtz coupling of various organomethyl dichlorosilanes, GPC, u.v. and i.r. analyses were performed. The i.r. spectra reveal hydrosilanes and siloxanes groups in the oligomer fractions. Possible sources of these unusual groups are discussed.

Preparation et caracteristiques d'un nouveau sel de transfert de charge conducteur electrique : TMTTF3-DETCNQ2 ☆

Abstract A new organic conductor TMTTF 3 - DETCNQ 2 of unusual stoichiometry and structure is described and its spectral properties and electrical conductivity between 300 - 100°K studied.

Basic biochemical investigations as rationale for the design of original antimalarial drugs. An example of phospholipid metabolism

The future of antimalarial chemotherapy is particularly alarming in view of the spread of parasite cross-resistances to drugs that are not even structurally related. Only the availability of new pharmacological models will make it possible to select molecules with novel mechanisms of action, thus delaying resistance and allowing the development of new chemotherapeutic strategies. We reached this objective in mice. Our approach is hunged on fundamental and applied research begun in 1980 to investigate the phospholipid (PL) metabolism of intraerythrocytic Plasmodium. This metabolism is abundant, specific and indispensable for the production of Plasmodium membranes. Any drug able to interfere with this Plasmodium membranes. Any drug able to interfere with this metabolism blocks parasitic development. The most effective interference yet found involves blockage of the choline transporter, which supplies Plasmodium with choline for the synthesis of phosphatidylcholine, its major PL, this is a limiting step in the pathway. The drug sensitivity threshold is much lower for the parasite, which is more dependent on this metabolism than host cells. The compounds show in vitro activity against P. falciparum at 1 to 10 nM. They show a very low toxicity against a lymphoblastoid cell line, demonstrating a total absence of correlation between growth inhibition of parasites and lymphoblastoid cells. They show antimalarial activity in vivo, in the P. berghei or P. chabaudi/mouse system, at doses 20- to 100-fold lower than their acute toxicity limit. The bioavailability of a radiolabeled form of the product seemed to be advantageous (slow blood clearance and no significant concentration in tissues). Lastly, the compounds are inexpensive to produce. They are stable and water-soluble.

STEREOCHEMISCHE UNTERSUCHUNG DER CYCLISIERUNG VON DIBROMDERIVATEN MIT PHENYLACETONITRIL UND PHENYLACETON

Die Kondensation von 1,4-Dibrom-pentan (I) mit den Acetonitrilen (II) ergibt in Gegenwart von Na-amid bei 80°C die beiden stereomeren Nitrile (III) und (IV).