André Mortreux

Metathesis of alkynes by a molybdenum hexacarbonyl–resorcinol catalyst

A mixture of molybdenum hexacarbonyl and a phenol reagent is an active and selective homogeneous catalyst for the metathesis of aromatic disubstituted alkynes.

Palladium-catalyzed carbonylative coupling of pyridine halides with aryl boronic acids

Abstract The carbonylative Suzuki cross-coupling of a variety of mono-iodopyridines and bromopyridines ( 1a,b , 3a–c , 5 ) catalyzed by palladium-phosphane systems has been studied to prepare benzoylpyridine derivatives ( 2 , 4 , 6 ). The selectivity and the rate of the reaction are highly dependent on the reaction conditions, i.e. nature of the palladium catalyst precursor, solvent, temperature and CO pressure. The main side-products arise from direct, non-carbonylative cross-coupling. Under optimized conditions, benzoylpyridines are recovered in high yields (80–95%). The order of reactivity decreases from iodo- to bromopyridines and from 2-, 4- to 3-substituted halopyridines. The reactivity of dihalopyridines has been investigated; 2,6-dibromopyridine ( 7 ) and 3,5-dibromopyridine ( 11 ) are selectively transformed into either the corresponding benzoyl-phenylpyridine ( 8 , 12 ) or the corresponding dibenzoylpyridine ( 9 , 13 ). Dissymmetric 2,5-dihalopyridines ( 15a,b ) are transformed into 2-benzoyl-5-bromopyridine ( 16 ) or 2,5-dibenzoylpyridine ( 17 ) in high yields.

A further breakthrough in biphasic, rhodium-catalyzed hydroformylation: the use of Per(2,6-di-O-methyl)-β-cyclodextrin as inverse phase transfer catalyst

Abstract Solvent free biphasic hydroformylalion of various water-insoluble terminal olefins can be achieved in high yields and sclcctivitics by using a water-soluble rhodium/triphenylphosphine trisulfonate catalyst and per(2,6-di-o-mclhyl)-β-cyclodcxtrin as inverse phase transfer catalyst. The catalytic activities were up to ten times higher than those observed without pcr(2,6-di-o-methyl)-β-cyclodextrin.

The aminophosphine-phosphinites and related ligands: synthesis, coordination chemistry and enantioselective catalysis

Abstract The synthesis and coordination chemistry of aminophosphine-phosphinites (AMPP) and closely related ligands is reviewed. Asymmetric catalytic reactions involving organometallic-AMPP complexes are presented. Examples of enantioselective C–C bond formation in the presence of nickel- (dienes and diene-olefins dimerization, allylic substitution) and palladium-AMPP catalysts (nucleophilic addition to allylic substrates), hydroformylation based on platinum and rhodium complexes, rhodium-based hydrosilylation, hydrogenation of CC and CO bonds in the presence of rhodium and ruthenium complexes and homo Diels-Alder catalyzed by cobalt species are presented.

Palladium-catalyzed carbonylative cross-coupling reactions of pyridine halides and aryl boronic acids: a convenient access to α-pyridyl ketones

Abstract The proper choice of solvent, catalyst precursor and CO pressure enables the easy and selective transformation of mono- and dihalopyridines into phenyl pyridyl ketones in 81–95% yields.

Rhodium catalyzed hydroformylation of water insoluble olefins in the presence of chemically modified β-cyclodextrins: evidence for ligand-cyclodextrin interactions and effect of various parameters on the activity and the aldehydes selectivity

Abstract The biphasic rhodium catalyzed hydroformylation of water insoluble olefins in the presence of chemically modified β-cyclodextrins has been investigated. The influence of various parameters, such as the nature of the β-cyclodextrin, the concentrations of phosphine or cyclodextrin and the temperature is illustrated using 1-decene as a model substrate. The formation of inclusion complexes between the different components of the system is also discussed on the basis of NMR experiments. The results indicate that the chemically modified cyclodextrins (CyDs) must not be considered only as inverse phase transfer catalysts but also as compounds which, by trapping the water soluble ligand, can modify the equilibria between the different catalytic species.

(β-Amino alcohol)(arene)ruthenium(II)-Catalyzed Asymmetric Transfer Hydrogenation of Functionalized Ketones − Scope, Isolation of the Catalytic Intermediates, and Deactivation Processes

The asymmetric transfer hydrogenation of functionalized ketones with (β-amino alcohol)(arene)RuII catalysts using 2-propanol as the hydrogen source has been studied. The structure of the catalyst has been systematically screened using a wide variety of [(η6-arene)RuCl2]2 complexes and β-amino alcohols R1CH(OH)CHR2NHR3, some of which were specifically designed for optimized performance, e.g. (1S,2R)-N-(4-biphenylmethyl)norephedrine (9o). The efficiencies of the catalytic combinations have been evaluated in the reduction of β-oxo esters and ketones bearing heteroatoms at the α-position. The catalyst precursor [{η6-p-cymene}{η2-N,O-(9o)}RuCl] (35), the 16-electron true catalyst [{η6-p-cymene}{η2-N,O-(9o1−)}Ru] (36), and the hydride [{η6-p-cymene}{η2-N,O-(9o)}RuH] (37) involved in the reduction process have been isolated, characterized by NMR and ESI-MS, as well as by X-ray crystallography in the case of 35, and their reactivities have been investigated. The results reveal two general trends regarding this catalytic process: (1) the apparent reaction rate and the enantioselectivity are largely controlled by the nature of the amine functionality of the chiral ligand and the arene ring of the RuII precursor; (2) side reactions occur between the ketone substrate and the active catalytic species that affect the concentration of the latter and consequently the apparent rate; the formation of inactive (β-diketonato)RuII complexes is demonstrated in the case of β-oxo esters.

A novel and convenient method for palladium-catalysed alkoxycarbonylation of aryl and vinyl halides using HCO2R/NaOR system

Abstract Aryl iodides, vinyl bromides and tricarbonyl(chloroarene)chromium complexes react under mild conditions with sodium alkoxides and alkyl formates as source of carbon monoxide in the presence of dichlorobis(triphenylphosphine)-palladium as catalyst to give the corresponding carboxylic esters in high yields.

17O NMR gives unprecedented insights into the structure of supported catalysts and their interaction with the silica carrier.

Flame silica was surface-labeled with (17)O, through isotopic enrichment of both siloxanes and silanols. After heat treatment at 200 and 700 °C under vacuum, the resulting partially dehydroxylated silica materials were investigated by high-field solid-state (1)H and (17)O NMR. More specifically, MQ MAS and HMQC sequences were used to probe the (17)O local environment. In a further step, these (17)O-tagged supports were used for the preparation of supported catalysts by reaction with perhydrocarbyl transition metal derivatives (zirconium tetraalkyl, tantalum trisalkyl-alkylidene, and tungsten trisalkyl-alkylidyne complexes). Detailed (17)O 1D and 2D MQ and HMQC MAS NMR studies demonstrate that signals in the Si-OH, Si-O-Si, and Si-O-metal regions are highly sensitive to local structural modifications, thanks to (17)O wide chemical shift and quadrupolar constant ranges. Experimental results were supported by DFT calculations. From the selective surface labeling, unprecedented information on interactions between supported catalysts and their inorganic carrier has been extracted.

Unprecedented dual behaviour of a half-sandwich scandium-based initiator for both highly selective isoprene and styrene polymerisation

Highly cis-1,4 polymerisation of isoprene and syndiospecific polymerisation of styrene were conducted using the same borohydrido half-sandwich scandium pre-initiator.