R. Spogliarich

Selective hydrogenation of unsaturated ketones by rhodium(I) complexes containing 2,2′-bipyridine ligand

Abstract The selective homogeneous reduction of CO groups in the presence of CC bonds with [Rh(Bipy)S 2 ] + or [Rh(Bipy) 2 ] + as catalyst was studied. Stereochemical features of the hydrogenation of substituted cyclohexanones with the two complexes are also reported.

Asymmetric transfer hydrogenation of ketones catalyzed by phosphine-rhodium(I) and -iridium(I) complexes

Abstract The asymmetric hydrogen transfer from propan-2-ol to prochiral ketones is effectively catalyzed by diphosphine complexes of iridium and rhodium. The influence of the reaction conditions on the activity and selectivity of the catalysts has been investigated.

Reduction of ketones via hydrogen transfer reactions catalyzed by rhodium(I) complexes

The reduction of ketones such as cyclohexanone or 4-t-butylcyclohexanone by hydrogen transfer from isopropanol is catalyzed by cationic rhodium complexes of the type [Rh(diene)P2]+ (diene = 1,5-cyclooctadiene or norbornadiene; P or P2 = mono or bidentate phosphine ligands) or by neutral Wilkinsons type compounds. Complexes containing chelating ligands show the highest activities.

Hydrogen transfer reactions catalyzed by rhodium(III)-and iridium(III)-tin(II) systems

Abstract The hydrogen transfer reaction from isopropanol to cyclohexanones is catalyzed by rhodium(III)-and iridium(III)-tin(II) systems. The influence of various parameters such as SnIII/MIII ratio,[H+] and [Cl-] on the reaction rate and on the stereoselectivity has been examined.

Homogeneous catalytic reduction of benzalacetone with carbon monoxide and water

Abstract The selective hydrogenation of benzalacetone to the corresponding saturated ketone PhCH 2 CH 2 COCH 3 with CO and water as the hydrogen source is catalyzed by [Rh(diene)L 2 ] + complexes (diene = 1,5-cyclooctadiene or norbornadiene; L 2 = mono- or bidentate phosphorous ligands) and by rhodium and iridium carbonyls. The effects of these catalysts in the water gas shift reaction are also reported.

Hydrogenation of ketones and olefins via hydrogen transfer catalyzed by rhodium and iridium phosphine complexes

Abstract The reduction of ketones and olefins by hydrogen transfer from isopropanol is catalyzed by tertiary phosphine complexes of rhodium and iridium. The influence of the nature of the ligands and of the reaction conditions on the catalytic activity has been investigated. The reduction of the carbonyl group in the presence of olefins is also reported.

Selective reduction of dienes to monoenes via hydrogen transfer reaction in the presence of carbonyl clusters

Abstract 1,5-Cyclooctadiene and 1,5-hexadiene are selectively reduced by hydrogen transfer from i-PrOH using Rh6(CO)16 as procatalyst. The first step of the reaction appears to be the formation of conjugated diene isomers, which are subsequently reduced to monoenes. Carbonyl clusters of Os, Ru and Ir can also be used, but their activities are lower and they predominantly catalyze isomerization.

Selective reduction of unsaturated ketones to unsaturated alcohols catalyzed by an iridium-phosphine system

Abstract The system formed in situ from [Ir(COD)Cl] 2 and P( o -MeOPh) 3 catalyzes the selective transfer hydrogenation of the carbonyl group in 5-hexen-2-one, the yield in unsaturated alcohol being maximum at high P/Ir ratios. This peculiar behavior is probably related to an intramolecular interaction between the substrate and the methoxy groups of the phosphine. The same system has also been tested with benzylidenacetone as substrate, yielding a certain amount of unsaturated alcohol together with saturated ketone and alcohol.

Selective hydrogenation of benzylideneacetone catalyzed by iridium diphosphine complexes

Hydrogenation of benzylideneacetone (PhCH=CHCOCH3) is catalysed by iridium diphosphine complexes of the type [Ir(P-P)2]+ (P-P = dpe, dpp, dpb, (S, S)-chiraphos, (R)-prophos,, (+)-diop and (S)-prolophos) and by systems formed in situ from [Ir(cod)Cl]2 or [Ir(cod)(OCH3)]2 (cod = 1,5-cyclooctadiene) and diphosphines. 1-Phenyl-1-buten-3-ol [PhCH=CHCH(OH)CH3] is selectively produced in high yields using [Ir(P-P)2]+ (P-P=diop, prolophos) as catalyst precursor or high P/Ir ratios in the systems prepared in situ. Optical yields up to 30% in the S(−)-unsaturated alcohol are obtained with chiral diphosphines as ligands. Catalytic results are given together with spectroscopie data and some equilibria are proposed to account for the different activities and selectivities observed in the hydrogenation. The length of the carbon atom chain in the diphosphine seems to play a crucial role in determining the distribution of products.

Water gas shift reaction homogeneously catalyzed by [Ir(diene)L2]+ complexes

Abstract The water gas shift reaction (WGSR) is homogeneously catalyzed by [Ir(diene)L2]+ (diene  1,5-cyclooctadiene, L and/or L2 are mono- or bi- dentate ligands with phosphorus or nitrogen as donor atoms). The catalytic activity is compared with that of other homogeneous systems.