Corinne Payrastre

A synthetic pathway to macrocyclic and optically active pentamethinium salts

Abstract The design of new types of azodyes with optical activity and macrocyclic structure was achieved by the generalization of the reaction of stabilized carboxonium ions with various primary and secondary amino compounds.

NEW DIAZA PENTADIENYLIUM SALTS (CYANINE DYES) DERIVED FROM N-SILYLATED PHOSPHINIMINES AND GUANIDINES

Abstract New synthetic methods for the preparation of pentadienylium cations (cyanine dyes) are developed in our laboratories. In particular the reaction of carboxonium derivatives on various primary and secondary amines is to be emphasized. This method is remarkably versatile to lead to new dyes hardly obtainable otherwise. It is applied here to the synthesis of previously unknown derivatives of N-silylated phosphinimines and guanidines where the conjugated polyenic system can be extended over the nitrogen atom on the phosphinimine or guanidine moiety. Spectrochemical results, mainly 31P, 13C NMR and UV are in accordance with these assumptions opening thus a new field of investigation for the reactivity of the aza-Wittig compounds and more generally for the physical applications (ie in optical devices).

Synthesis of new pentacarbon chain streptocyanines (pentamethinium salts)

Abstract Pentacarbon chain streptocyanines, symmetrical and dissymmetrical, mono- and dicationic are obtained by action of aliphatic mono- and diamines on pentacarbon carboxonium salts.

Derives organiques de l'arsenic dicoordine synthese et caracterisation de nouveaux cations arsenium possedant l'enchainement N-As-N

Abstract Four new cyclic and acyclic dicoordinated arsenium salts were obtained by action of AlCl3 and CF3SO3SiMe3 (or CF3SO3inAg) on tricoordinated chloroarsenic precursors.

Superoxide-induced bleaching of streptocyanine dyes: Application to assay the enzymatic activity of superoxide dismutases

With the aim of developing a novel superoxide dismutase (SOD) activity assay, a series of polymethinium salts (streptocyanines) were prepared and studied for their ability to be reduced by superoxide radical anion generated either from the pyrogallol autoxidation or by the xanthine oxidase-catalyzed oxidation of xanthine. The nonacarbon chain streptocyanine 9Cl(NEt(2))(2) was found to be relatively stable in neutral buffered aqueous solutions, to be reduced at a significant rate by superoxide, and addition of iron-dependent superoxide dismutase (Fe-SOD) prevented its bleaching, thus constituting a good candidate as a possible superoxide indicator in a spectrophotometric SOD assay. The values found to be optimal for a SOD assay were defined as pH 7.4, wavelength 728nm, xanthine and xanthine oxidase as superoxide source, and a reaction time of 5min. Based on the color change caused by the superoxide-induced bleaching of the streptocyanine, a qualitative colorimetric method for the SOD activity detection is proposed, enabling visual detection within a short time without any instrument.

Synthesis and Antimalarial Properties of Streptocyanine Dyes

Several streptocyanine dyes were synthesized that contain polymethine chains of varying length. Their in vitro antimalarial activities were evaluated against the virulent P. falciparum parasite. In addition to the influence of polymethine chain length, the effects of structural modifications at nitrogen end groups, para substitution of the phenyl groups, and counter‐anions were studied. The most potent antimalarial activities were found for heptacarbon chain streptocyanines, with an IC50 value of 60 nM. Interestingly, most of the compounds were less cytotoxic toward the mammalian cells tested. The best selective toxicity profiles were found for pentacarbon chain streptocyanines, which have a good in vitro specificity index.

SYNTHESIS OF PENTADIENYLIUM IONS WITH N-SILYLATED PHOSPHAIMINES, CHARACTERIZATION AND REACTIVITY

Abstract By condensation of a carboxonium salt with N-silylated phosphaimines new types of pentadienylium salts are obtained. These new compounds are characterized by NMR spectroscopy, UV and mass spectra. Their aza-Wittig reactivity towards isocyanides is described.

Dioxaphosphorinane-constrained nucleic Acid dinucleotides as tools for structural tuning of nucleic acids.

We describe a rational approach devoted to modulate the sugar-phosphate backbone geometry of nucleic acids. Constraints were generated by connecting one oxygen of the phosphate group to a carbon of the sugar moiety. The so-called dioxaphosphorinane rings were introduced at key positions along the sugar-phosphate backbone allowing the control of the six-torsion angles α to ζ defining the polymer structure. The syntheses of all the members of the D-CNA family are described, and we emphasize the effect on secondary structure stabilization of a couple of diastereoisomers of α,β-D-CNA exhibiting wether B-type canonical values or not.

REACTIVITY OF PHOSPHORYLATED PENTADIENYLIUM SALTS TOWARDS ISOCYANIDES: SYNTHESIS OF AMINOPYRIDINE PHOSPHONIUM SALTS

Abstract New cyanines dyes with phosphaimino substituents though engaged in delocalized system react with mono or diisocyanides in an aza-Wittig like reaction to give α-aminopyridines with phosphonium side chain. The final structure was determined by X ray.

Chlorodialkylaminoarsenium salts : synthesis and rirst arsenium reactivity examples

Abstract Chlorodialkylaminoarsenium trifluoromethanesulfonates are obtained by reaction of dichlorodialkylaminoarsanes (R 2 NAsCl 2 ) on silver trifluoromethanesulfonate (CF 3 SO 3 Ag). Their reactivity, (first example of arsenium one), with silylated reagents of the type Me 3 SiX leads either to neutral (X = CN) cyanodialkylaminochloroarsanes or to arsenium salts (X = NMe 2 ) like bis(dialkylamino)arsenium trifluoromethanesulfonates.