Denis Neibecker

Rhodium-catalysed hydroamination-hydroarylation of norbornene with aniline, toluidines or diphenylamine

Abstract The condensation of aniline, toluidines or diphenylamine with norbornene tetrahydrofuran is promoted by a system generated from Li n Bu, ArNH 2 and [(PEt 3 ) 2 RhCl 2 ]. Aniline and m - and p -toluidines lead to a mixture of hydroamination and hydroarylation products whereas o -toluidine and diphenylamine lead to the hydroarylation product only. When conducted in the amine as solvent, the reaction is catalytic with respect to both lithium and rhodium.

Synthesis and evaluation of the catalytic properties of homo- and hetero-bimetallic complexes containing bridging diphenylphosphido ligands

The bimetallic complex [(CO)3Ru(μ-PPh2)2Ru(CO)3] (1) has been prepared in 42% yield by the reaction of [Ru3(CO)12] with t

Phospholes as ligands for rhodium systems in homogeneously-catalysed hydroformylation reactions: Part 1. Stereoelectronic properties of the ligands and hydroformylation of 1-hexene

Abstract The stereoelectronic properties of various phospholes were determined and discussed in terms of Tolmans electronic ν and steric θ parameters. The selected phospholes, associated with rhodium, were used in the catalytic hydroformylation of 1-hexene and compared to triphenylphosphine under typical hydroformylation conditions (80 °C, 20 bar syngas). One phosphole, namely 1,2,5-triphenylphosphole (TPP), has been found to be by far superior to triphenylphosphine (about 10 times more active and 10% more selective). Most importantly, the rhodium-TPP system does not seem to be sensitive to the P/Rh ratio.

Iron pentacarbonyl-catalysed aminomethylation of alkenes: Some intriguing observations

Abstract The reaction of piperidine with ethylene in the presence of Fe (CO) 5 affords a mixture of N -ethyl- (minor product) and N - n -propylpiperidine (major product). Reactions conducted for 14 h at 170°C in the presence of Fe (CO) 5 , and water afford N - n -propylpiperidine with a turnover of 3.3 in the absence of an external source of carbon monoxide.

Expedient synthesis of (Ph3P)2Fe(CO)3

Abstract A one-step, high yield synthesis of highly pure (Ph 3 P) 2 Fe(CO) 3 from KHFe(CO) 4 and Ph 3 P in ethanol is described.

Improved synthesis of KHCr(CO)5 and comparative coordination chemistry from KHCr(CO)5 and KHFe(CO)4

Abstract A practical procedure for the selective preparation of KHCr(CO)5 is described. The use of a potassium cation in the coordination chemistry of the [HFe(CO)4]− anion is completed and extended to the coordination chemistry of the [HCr(CO)5]− anion: CO-substitution by phosphites, phosphines and phosphinites, and H-abstraction by aminophosphines. Most of the observed differences in reactivity between KHFe(CO)4 and KHCr(CO)5 can be rationalized by the stronger acidity of KHFe(CO)4.

Coordination chemistry of mononuclear iron carbonyl complexes

Abstract This review is devoted to recent advances in mononuclear iron carbonyl coordination chemistry starting from M+[EFe(CO)4]− complexes (E=H, RCO) easily obtained from Fe(CO)5. E=H. The reaction of K+[HFe(CO)4]− with phosphines, phosphites and phosphinites (abbreviated “P”) allows selective syntheses for a large range of (phosphane)iron carbonyl complexes such as Fe(CO)3P2, Fe(CO)2P3, H2Fe(CO)2P2, K+[HFe(CO)3P]− and K+[HFe(CO)2P2]−. In the special case of the new optically active phosphinite–ammonium ligands P–(*)–N+ named “ephosium” and “valphosium”, optically active zwitterionic complexes [HFe(CO)3P]−–(*)–N+ have been obtained, the structures of which have been studied both in the solid state and in solution. The above reactions have been shown to involve first a CO substitution, generating [HFe(CO)3P]− species which then react further, the final product depending on both the nature of the solvent (protic or not) and the steric and electronic properties of the phosphane. In contrast, reaction with tri(amino)phosphines proceeds by substitution at the phosphorus atom, affording the Collman dianion [Fe(CO)4]2− and [(R2N)2PH]Fe(CO)4 complexes the reactivities of which with KH have been studied. E=RCO. The reaction of lithium aldimines such as [t-BuNue605C(t-Bu)]Li with Fe(CO)5 generates lithium (α-iminoacyl)tetracarbonylferrates, which are imino-protected equivalents of the rare [(CO)4Fe–CO–CO–Z]− sequence. Alkylation with Me3OBF4 yields the corresponding α,β-unsaturated Fischer carbene complexes. The reaction of RCO(Li)Fe(CO)4 (R=alkyl) with PPh2Cl (or PPhCl2) cleanly proceeds by a tandem acylation–complexation to afford the complexed acylphosphines [RCOPPh2]Fe(CO)4 (or [RCOPPhCl]Fe(CO)4) in good yield.

Variable temperature multidimensional NMR study of anionic Rh(I) anilido [(R3P)2Rh(NHPh)2]−, M+ complexes

Variable temperature multidimensional NMR studies of [(R3P)2Rh(NHPh)2]−, Li+ complexes enabled the detection of activation of one aromatic ortho proton of each anilido ligand. This activation is not attributable to a Cue5f8Houe5f8Rh agostic interactions, but rather to interaction with lithium, resulting from a short distance between the lithium atom and one of the aromatic ortho hydrogens of each anilido ligand.

Highly regioselective iron-promoted hydrocarboxylation of styrene

Abstract The reaction of Li[HFe(CO)4] with styrene under carbon monoxide (1 atm) in a H2O / iPrOH / LiOH system promotes a highly regioselective (98%) hydrocarboxylation to 2-phenylpropionic acid. In contrast, when conducted under argon, the reaction predominantly (90%) leads to 3-phenylpropionic acid.

SYNTHESIS OF 1, n-BIS (2,5–DIPHENYLPHOSPHOL-1-YL) ALKANES

Abstract 1, n-bis (2,5-diphenylphospholyl)alkanes (n = 2–6) are easily prepared in a one pot high-yield reaction and fully characterized by multinuclear NMR spectroscopy.