Jean-Pierre Majoral

Synthesis of the first stable metadithiophosphonate

Synthese du dithioxo tri-t-butyl-2,4,6 phenyl phosphorane par reaction de la dimethylaminomethylene tri-t-butyl-2,4,6 phenyl phosphine avec le soufre S 8

Mannodendrimers prevent acute lung inflammation by inhibiting neutrophil recruitment

Mycobacterium tuberculosis mannose-capped lipoarabinomannan inhibits the release of proinflammatory cytokines by LPS-stimulated human dendritic cells (DCs) via targeting the C-type lectin receptor DC-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN). With the aim of mimicking the bioactive supramolecular structure of mannose-capped lipoarabinomannan, we designed and synthesized a set of poly(phosphorhydrazone) dendrimers grafted with mannose units, called mannodendrimers, that differed by size and the number and length of their (α1→2)-oligommanoside caps. A third-generation dendrimer bearing 48 trimannoside caps (3T) and a fourth-generation dendrimer bearing 96 dimannosides (4D) displayed the highest binding avidity for DC-SIGN. Moreover, these dendrimers inhibited proinflammatory cytokines, including TNF-α, production by LPS-stimulated DCs in a DC-SIGN–dependent fashion. Finally, in a model of acute lung inflammation in which mice were exposed to aerosolized LPS, per os administration of 3T mannodendrimer was found to significantly reduce neutrophil influx via targeting the DC-SIGN murine homolog SIGN-related 1. The 3T mannodendrimer therefore represents an innovative fully synthetic compound for the treatment of lung inflammatory diseases.

Photochemical reactions of phosphaalkenes

Abstract Photolysis of phosphaalkenes leads to an inversion of polarity of the phosphorus carbon double bond and to a cleavage into transient phosphinidene and carbene ; unexpected alcoholysis of a P III -C bond and the [4+2] cycloaddition of a linear phosphaalkine on a diene are also reported.

A new route to bis(2,4,6-tri-tert-butylphenyl)diphosphene via silylated compound

Abstract A new synthesis of stable diphosphene is reported. δ 31 P value is reinvestigated.

Reactivite de quelques phosphor(III)adamantanes et de quelques analogues tricycliques

Abstract The reactivity of some phosphor(III)adamantans has been investigated. New ways of obtention of P(V)derivatives are described.

Photolytic rearrangement of phosphorus azide : evidence for a transient metaphosphonimidate.

Durch Photolyse von Diphenyl-phosphorylazid (I) entsteht intermediar das Metaphosphonimidat (II), das in Abwesenheit von reaktiven Komponenten zum Dimeren (III) abreagiert.

Chlorophosphéniums, précurseurs de nouveaux cations du phosphore dicoordonné

Abstract This paper reports the reaction of chlorophosphenium cations R2N-P+-Cl AlCl4- (R = iPr, Et) with silyl reagents Me3SiX (X = -NMe2, -CN, -NP(NMe2)3, -NCS, and OCH2t-Bu) leading to 10 new mixed phosphenium cations ( 3 to 12 ). Five of them ( 3 to 8 ) are stable, in particular with the phosphazenyl group : iPr2N-P+ -NP(NMe2)3 (7) the stability is due to the delocalization of the positive charge on the [-P-N-P] system. Trimethylsilyl trifluoro methane sulfonate acts as a versatile reagent towards chlorophosphines ; it reacts with (R2N)2PCl leading to the corresponding phosphenium cation with the triflate anion CF3SO3- , as counter ion, but not with iPr2NPCl2. Nevertheless the mixture iPr2NPCl2 Me3SiOSO2CF3 generates the chlorophosphenium cation in presence of Me3SiX giving rise to iPr2N-P+ -X CF3SO3 in a one pot reaction. Surprisingly, the chlorophosphenium (Me2N)3PN-P+ -Cl undergoes a charge transfer with the transient generation of a functionalized dicoordinated phosphorus derivative (Me2N)3P+-NPCl which dimerizes into the corresponding diazadiphosphetidine 21 .

Les dithiaphospho(III)lanes-1,3,2, noveaux precurseurs de derives du phosphore penta- et dicoordine

Abstract The synthesis of new spirodithiaphospholans is described. Lability of these compounds allows to obtain by an orginally way dicoordinated phosphorus derivatives.

Hétérocycles contenant du phosphore—XIII. Etude par spectrographie infrarouge de quelques dioxaphosphorinanes-1,3,2

Abstract The i.r. spectra of forty-one 1,2,3-dioxaphophorinans have been studied. The dependence of the phosphoryl frequency upon the conformation of the heterocycle is discussed. The characteristic absorption frequencies associated with P → S, P—Cl, P—C 6 H 5 and P—O—C 6 H 5 bonds are given.

Low temperature synthesis of ordered mesoporous stable anatase nanocrystals: the phosphorus dendrimer approach

The scarcity of low temperature syntheses of anatase nanocrystals prompted us to explore the use of surface-reactive fourth generation phosphorus-dendrimers as molds to control the nucleation and growth of titanium-oxo-species during the sol-gel mineralization process. Unexpectedly, the dendritic medium provides at low temperature, discrete anatase nanocrystals (4.8 to 5.2 nm in size), in marked contrast to the routinely obtained amorphous titanium dioxide phase under standard conditions. Upon thermal treatment, heteroatom migration from the branches to the nanoparticle surface and the ring opening polymerization of the cyclophosphazene core provide stable, interpenetrating mesoporous polyphosphazene-anatase hybrid materials (-P[double bond, length as m-dash]N-)n-TiO2. The steric hindrance of the dendritic skeleton, the passivation of the anatase surface by heteroatoms and the ring opening of the core limit the crystal growth of anatase to 7.4 nm and prevent, up to 800 °C, the commonly observed anatase-to-rutile phase transformation. Performing this mineralization in the presence of similar surface-reactive but non-dendritic skeletons (referred to as branch-mimicking dendrimers) failed to generate crystalline anatase and to efficiently limit the crystal growth, bringing thus clear evidence of the virtues of phosphorus dendrimers in the design of novel nanostructured materials.