Jean-Jacques Brunet

Cobalt carbonyl catalyzed sRN1 carbonylation of aryl and vinyl halides by phase transfer catalysis

Abstract The phase transfer catalyzed, cobalt carbonyi catalyzed carbonylation (1 atm. P.) of aryl and vinyi bromides under photostimulation (350 nm) affords the corresponding unsaturated acids in high yield.

Activation of reducing agents. Sodium hydride containing complex reducing agents : XIV. NaCoCO4 as an SRN1 nucleophile in the carbonylation of aryl halides by CoCRACO at atmospheric pressure. New preparation of NaCoCO4 by NaH reduction of dicobalt octacarbonyl

Abstract The only detectable cobalt carbonyl species present in CoCRACO (NaH/t-AmONa/Co(OAc) 2 /CO) (t-Am = tert-amyl) is NaCoCO 4 . The simultaneous presence of NaH, t-AmONa, NaCoCO 4 and some soluble, non-carbonyl, cobalt species allows highly catalytic carbonylation of C 6 H 5 Br under very mild conditions, while NaCoCO 4 alone can carbonylate C 6 H 5 Br under irradiation (350 nm). In the presence of t-AmONa, the reaction is highly catalytic with respect to cobalt. These results strongly suggest a S RN 1 mechanism. It is suggested that catalytic carbonylations with CoCRACO take place by a S RN 1, electron-initiated, reaction. A new, very convenient method of preparation of NaCoCO 4 by quantitative reduction of Co 2 CO 8 with NaH is also described.

Activation of reducing agents: sodium hydride containing complex reducing agents. XIX: Homo coupling of aryl and vinyl halides promoted by ligand modified NiCRA (NaH-RONa-Ni(OAc)2)

Abstract The preparation of NiCRA (NaH-t-AmONa-Ni(OAc) 2 ) in the presence of 2,2′-bipyridine (bpy) leads to a new reagent (termed NiCRA-bpy) which is shown to be one of the most efficient Ni based reagents reported so far for the homocoupling of aryl and vinyl halides (including chlorides). The homo coupling of cis - and trans -β-bromostyrenes is shown to be stereospecific.

Rhodium-mediated 100% regioselective oxidative hydroamination of α-olefins.

The system generated from lithium anilide and [(Et3P)2RhCl]2 catalyses (turnover 21) the regioselective condensation of aniline with styrene to give a mixture of PhNH-CH(CH3)Ph (hydroamination product) and PhNue5fbC(CH3)Ph (oxidative hydroamination product) in c.a. 1/2 ratio. This 100% regioselective oxidative hydroamination has been confirmed in the case of 1-hexene.

Activation of reducing agents. Sodium hydride containing complex reducing agents : VIII. New complex reducing agents

Abstract Activated sodium hydride (NaHue5f8RONa) was treated with Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Zr, Mo, Pd, W salts to give the new complex reducing agents NaHue5f8RONaue5f8MX n (CRA). Their reactivities were examined for reduction of 1-bromonaphthalene. In most cases, the CRA exhibited very good reducing abilities, which can be varied by changing the solvent, the alkoxide, or the temperature. Moreover, some CRA act as coupling agents for aromatic halides. Easy to prepare and handle on a preparative scale, CRA must be regarded as very promising tools for organic synthesis.

Alkylation des énolates de cétones par les alkyl chlorocyclohexenes: Intervention de cyclohexynes et/ou de cyclohexadiènes-1,2☆

Resume Les bases complexes “NaNH2-enolates” dans le THF sont capables dengendrer, a partir de chlorocyclohexenes a halogǹe vinylique, des cycloalcynes aussi bien que des cycloalcadienes-1,2. Les enolates de cetones se condensent sur ces deux types dintermediaires; les cyclohexadienes-1,2 conduisent a des alcools alkylidene cyclobutaniques; dans certains cas, les cyclohexynes conduisent a des cyclobutenols. De plus, ces reactions donnent aisement acces a un certain nombre de cetones nouvelles peu accessibles par ailleurs. Le sens de lelimination depend a la fois de la structure du derive halogene et du milieu “base-nucleophile-solvant”.

“Methyldiopium” and “methylbinapium”, chiral phosphoniumphosphine ligands

Abstract Monomethylphosphoniums derived from ( R,R )-diop (“methyldiopium” 2·I ) and ( R )-binap (“methylbinapium” 7·I ) are described. The crystal structure of 7·I is given, and 2·I is shown to act as a ligand of carbonyliron.

Regioselective dechlorination of 2,3-dichloronitrobenzene into 3-chloronitrobenzene and regioselective dechlorination–hydrogenation into 3-chloroaniline

Abstract Tetrakis(triphenylphosphine)palladium, Pd(PPh 3 ) 4 , is an efficient catalyst for the selective dechlorination of 2,3-dichloronitrobenzene into 3-chloronitrobenzene. During the reaction the selectivity is over 90% in a very reproducible manner and the reaction can be stopped at the maximum selectivity. Pd(PPh 3 ) 4 is also a catalyst for the one-pot transformation of 2,3-dichloronitrobenzene into 3-chloroaniline (selectivity >60%).

Chiral diphospholes: III. Improved synthesis and coordination chemistry of (R,R)-DIPPOP

Abstract An improved, 90% yield synthesis of the chiral diphosphole, (R,R)-DIPPOP (1) is reported. The reactions of 1 with nickel, palladium, platinum and rhodium complexes are examined. 1 does not react with NiCl2. With PdCl2 and PtCl2 it forms various cis and trans diphosphine-bridged cyclooligomers of undetermined ring size. The rhodium complexes [Rh(cod)2]BF4, [Rh(acac) (cod)] and {Rh(μ-CI)(cod)}2 are good precursors for the synthesis of [Rh(cod){(R,R)-DIPPOP}]BF4, (8), [Rh(acac) {(R,R)-DIPPOP}],(9), and {Rh(cod)Cl}2{μ-P,P′-(R,R)-DIPPOP}, (10), which are fully characterized by multinuelear NMR spectroscopy.

Condensations en milieu aprotique d'enolates de cetones sur le chloro-1 cycloheptene en presence de bases—II : Synthese de bicyclo[5.2.0]Nonene-1 ols-8

Resume La condensation en milieu aprotique des enolates de la diisopropyl et de la methyl phenyl cetone sur le chloro-1 cycloheptene, conduit essentiellement a des bicyclo [5.2.0] nonene-1 ols-8. Lorientation de ces reactions en fonction du solvant est etudiee et le mecanisme de ces reactions est discute.