Michel Sanchez

Spirophosphoranylation d'α-aminoacides—I : Preparation et tautomerie1

Resume Une vingtaine de spirophosphoranes nouveaux (Tableaux 1 et 2) ont ete prepares en faisant reagir les &alpha-aminoacides sur des composes du phosphore tricoordine possedant un groupement partant convenable. Dans le cas du compose 1i , un equilibre chaǐne-cycle P III P v a ete mis en evidence.

A new synthesis of 1-phosphaalkyne via phosphaalkene with palladium(O) complex

Reaction of the readily available phosphaalkene ArP=CCl2 (1; Ar = 2,4,6-t-Bu3C6H2) with tetrakis(triphenylphosphine)palladium(O) affords the phosphaalkyne Ar-CP (3) in almost quantitative yield. The observed transformation was interpreted as a multi-step process including the generation of the phosphaisocyanide Ar-PC and its subsequent rearrangement into phosphaalkyne Ar-CP.

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 .

Synthesis of 2-(diphenylphosphino)phenolato and 2-(diphenylphosphinomethyl)-4-methylphenolato complexes of titanium and zirconium. X-ray characterization of [(η5-C5H5)2ZrCl(OC6H4PPh2] and [(η5-C5H5)2 Zr(OC6H4PPh2)2]

Abstract Complexes [(C 5 H 5 ) 2 MCl 2 ] (MTi, Zr) react with the 2-(diphenyl-phosphino)phenol HO(C 6 H 4 )PPh 2 in the presence of imidazole to give the corresponding complexes [Cp 2 ZrCl(OC 6 H 4 PPh 2 )], 1 and [Cp 2 M(OC 6 H 4 PPh 2 ) 2 ] ( 2 : MTi; 3 : MZr). Under the same experimental conditions, the bulkier ligand 2-(diphenylphosphinomethyl)-4-methylphenol HO(C 6 H 3 -(CH 3 )CH 2 PPh 2 failed to react with [Cp 2 MCl 2 ] (Ti or Zr) but with Cp 2 Zr(CH 3 ) 2 gives the methyl complex [Cp 2 Zr(CH 3 ){O(C 6 H 3 )(CH 3 )CH 2 PPh 2 }], 4 and [Cp 2 Zr[O(C 6 H 3 )(CH 3 )CH 2 PPh 2 ] 2 ], 5 . Compounds 1 and 3 crystallize from CH 2 Cl 2 solution, and their structures have been determined. The relatively short ZrO bond distance of 1.979(7) A, and the ZrOC bond angle of 160.2(5)°, in one phenoxy ligand of 3 suggest significant double bonding between Zr and O atoms. Chemical reduction of 1 with Na/Hg gives the expected cyclic P -metallated Zr III species characterized by EPR ( g = 1.976; a( 31 P ) = 14.6 G ). Preliminary data indicate that 3 acts as a diphosphine ligand upon reaction with [{Rh(CO) 2 Cl} 2 ].

Synthesis, structure and bonding properties of 3-phosphoindoles analogues of group 15

Abstract We present the synthesis and the characterization of new benzazadiphospholes 3, 4 and the parent compounds 5 and 6 with a P=As and a P=Sb double bond. The theoretical calculations, the photoelectron spectra and the reactivity of 2 are also discussed.

Structure of the Cycloaddition Products of Pyrido[2,1-a]isoindole with Maleimide Derivatives: X-ray Diffraction Analysis and1H NMR Variable-Temperature Spectra

Investigation of the cycloaddition reaction under thermodynamic control of pyrido[2,1-a]isoindole with maleimide derivatives revealed a new rearrangement leading to 2-{2′-[(1R)2,5-dioxopyrrolidinylidene]-2′-[(1R)-2,5-dioxopyrrolidinyl)methyl]}phenylpyridine. Their structure was confirmed by X-ray diffraction analysis. The atropisomeric properties of the obtained compounds were examined in a detailed NMR spectroscopic study. Dependence of the spectra on temperature was investigated, and coalescence temperatures and conversion barriers between the corresponding atropisomers determined.

EXTENSION OF THE STAUDINGER REACTION TO THE PHOSPHENIUM CATION [—P—]+: SYNTHESIS OF A NEW CLASS OF TETRAVALENT TRICOORDINATED PHOSPHORUS CATIONS

Abstract Three types of P[dbnd]N phosphazene bonds are known: and R3 P[dbnd]N—R. here classified according to the coordination numbers: 2,3,4 and valences 3,5,5, respectively. In this communication we describe a new phosphazene bond in a cation having a coordination number three and valence four:

Newly substituted pentamethine merocyanines. Part 1: Synthesis, physical properties, and synthetic applications

Abstract New 1,5-substituted pentamethine merocyanine dyes were synthesised in high yields. Their reaction towards acid chlorides or anhydrides leads to new hemicarboxonium salts with enhanced reactivity due to their better leaving groups. They are able to combine with soft nucleophiles to obtain a new cyanine dyes series. Thus, these merocyanines may be used as stable intermediate reagents in cyanine synthesis. Moreover, from a theoretical point of view, the synthesis of substituted derivatives of the well-known polyenic donor acceptor models for non-linear optics, opens the route to physicochemical determinations of their effects on the polarisation of the chain and the bond length alternation (Part 2 of study in progress).

The phosphaalkene-phosphenium cations (R2N)2C=P-P+-NR′2 a route towards diphosphenes and phosphaallylic cations

Abstract Phosphaalkene-phosphenium cations (R2N)2C=P-P+-NR′2 4a,b have been generated by halide abstraction from the corresponding chlorophosphines 2a,b or direct condensation of phosphaalkenes (R2N)2C=P-SiMe3 1 with chlorophosphenium cation 3a. The fast valence isomerization of 4a,b towards diphosphenes 5a,b and the unexpected formation of 2-phosphaallylic salts 7a,d via 1,3-tetraalkylformamidinium substituted cyclotetraphosphanes 6a,d have been observed.

Nouveaux Cations Phosphores A Enchainement P—N—PN+ (N = 1.2) Comportant Les Coordinences 2,3 Et 4 Du Phosphore

Abstract Novel recent results with mono- and bisphosphocations of P—N—-P compounds are reported.