M.-C. Senechal-Tocquer

Reactivity of carbanions of Fischer-type carbene complexes with pyrylium salts. Synthesis of new γ-methylenepyran carbene complexes via an addition-oxidation-deprotonation process

Abstract The condensation reaction between γ-unsubstituted pyrylium salts and carbanions of Fischer-type carbene complexes allowed the synthesis of new γ-methylenepyran carbene complexes. 13C NMR data and single cristal X-ray analysis suggest a delocalisation of the oxygene lone pair of the heterocycle.

Mono et dinitrosation en position benzylique des complexes du benz'ene chrometricarbonyle. Synth'ese directe d'oximes et d'hydroximates

Abstract In basic media, aromatic hydrocarbons and benzylmethylethers complexed by Cr(CO)3 units are readily nitrosated at the benzylic position bytBuONO, giving rise to Z and E oximes and hydroximates in moderate to excellent yields. With the meta-xylene and isochromane complexes it is possible to obtain a dinitrosation.

Synthèse directe de phénylpyruvates chromé tricarbonyle. Influences de la substitution sur la nature cétonique ou énolique des produits isolés, et du groupement Cr(CO)3 sur l'équilibre tautomère

Abstract Phenylpyruvate derivatives can be readily obtained as stable enols and ketones via a new functionalization of arene Cr(CO)3 complexes. An X-Ray structure and theoretical calculations indicate that conjugation stabilizes the enol forms. The complexation of phenylpyruvic acid lowers the conjugation and shifts the heto-enolic equilibrium to the ketonic form.

Addition de carbanions α benchrotréniques sur divers aldéhydes non énolisables; évolution des produits primaires d'addition par oxydation d'Oppenauer-Woodward, influence de la substitution

Abstract Aromatic hydrocarbons complexed with a Cr(CO) 3 unit react with benzaldehydes and furfural in THF and in the presence of t-BuOK at the benzylic position to give condensation products in good yields. Formation of ketones by “in situ Oppenauer-Woodward” oxidation is observed. Influence of ring substituents on this formation is discussed.

Formation et reactivite des carbanions benchrotreniques dans le thf. addition d'oxalate d'ethyle et de benzaldehyde. evolution des produits d'addition par oxydation d'oppenauer-woodward

Abstract Aromatic hydrocarbons complexed by a Cr(CO) 3 unit react in THF and in the presence of t-BuOK, at the benzylic position with (COOEt 2 and PhCHO to give good yields of condensation products. With PhCHO formation of ketone via “in situ” Oppenauer—Woodward oxidation, is observed.

Reaction of carbanion of Fischer-type carbene complexes with pyrylium salts. One pot substituted benzophenones formation by subsequent cyclization and double hydrogen β-elimination

Abstract Carbanions of Fischer-type carbene complex react with pyrylium salts. The unstable dienone formed gives substituted benzophenones after ring-closure and aromatization by double hydrogen β -elimination.

Acylation selon Friedel et Crafts de doubles liaisons carboncarbone, via des carbocations α-benchrotréniques

Abstract Friedel-Crafts acylation of several carboncarbon double bonds conjugated with a benzenechromium tricarbonyl group, proceeds via stabilised carbenium ions. Reactivity and structure of this intermediates have been investigated.

Voie d’accès aux sels de pyrylium γ-benchrotréniques synthèse des premiers sels de pyrylium organométalliques à cycles condensés Etude RMN et application à la synthèse de nouveaux complexes du benzène chrometricarbonyle

Resume Diacetylation of benehrotrenic alkenes by acetic anhydride and weak Lewis acid (ZnCl 2 , BF 3 -OEt 2 ) is reported. A series of γ-benchrotrenic pyrylium salis is obtained together with the mono and the diacetylated products. The first organometallic fused rings pyrylium salts are obtained. In connection with the electron donating effect of the Cr (CO) 3 group, the influence of rings deconjugation on NMR data is discussed. Finally the reaction of acyclic and cyclic γ-benchrotrenic pyrylium salts with nucleophiles is described.

Déprotonation des allylbenzènes chrometricarbonyle en milieu basique. Etude RMN 1H et 13C et réeactivité des anions allyliques: influence électronique et stérique du groupement chrometricarbonyle

Abstract 1H and 13C NMR study of allylic anions obtained in basic media from allylbenzene Cr(CO)3 and propenylbenzene Cr(CO)3 or [Cr(CO)32 is reported. A comparison with uncompleted anions literature results allows to specify the structure of the anion and the electronic effect of the Cr(CO)3 group. About NMR study of the diarylpropenide anions Cr(CO)3 or [Cr(CO)3]2 suggests that a Cr(CO)3 group migrates toward the allylic system. Finally the addition of RX derivatives on these anions is reported.

Action d'ylures de phosphore stabilisés sur divers aldéhydes α,β éthyléniques Fe(CO)4 et Fe(CO)3P(OMe)3. Synthèse de diènes Fe(CO)4 et Fe(CO)3P(OMe)3; influence de la substitution sur le site de complexation

Abstract α,β-Unsaturated aldehydes complexed at the CC bond with Fe(CO)3L units (L = CO, L = P(OMe)3), readily react with stabilized phosphoranes. When L = CO, butadieneiron tetracarbonyl complexes are formed in 30 minutes. This reactivity contrasts with previous reports on these complexes. When the starting α,β-unsaturated aldehyde complexes are β-monosubstituted the metallic group moves to the double bond formed.