(De)hydrogenation reactions catalyzed by manganese(I) complexes

Pour répondre aux enjeux économiques et sociaux modernes, le développement de catalyseurs organométalliques à base de métaux abondants et bon marché, comme alternatives aux catalyseurs historiques basés sur les métaux précieux, connaît un essor constant depuis deux décennies. L’objectif du présent travail doctoral a été de développer des catalyseurs à base de manganèse, troisième métal de transition le plus abondant après le fer et le titane, et précédemment principalement utilisé en oxydation, pour les réactions de (dé)-hydrogénation.To meet modern economic and social challenges, the development of inexpensive and abundant metal-based organometallic catalysts, as alternatives to historical catalysts based on precious metals, has been growing steadily for two decades. The aim of this doctoral work was to develop catalysts based on manganese, which is the third most abundant transition metal after iron and titanium, and previously mainly used in oxidation, for (de)-hydrogenation reactions

Réactions de (dé)hydrogénation catalysées par des complexes de manganèse(I)

To meet modern economic and social challenges, the development of inexpensive and abundant metal-based organometallic catalysts, as alternatives to historical catalysts based on precious metals, has been growing steadily for two decades. The aim of this doctoral work was to develop catalysts based on manganese, which is the third most abundant transition metal after iron and titanium, and previously mainly used in oxidation, for (de)-hydrogenation reactions.Pour répondre aux enjeux économiques et sociaux modernes, le développement de catalyseurs organométalliques à base de métaux abondants et bon marché, comme alternatives aux catalyseurs historiques basés sur les métaux précieux, connaît un essor constant depuis deux décennies. L’objectif du présent travail doctoral a été de développer des catalyseurs à base de manganèse, troisième métal de transition le plus abondant après le fer et le titane, et précédemment principalement utilisé en oxydation, pour les réactions de (dé)-hydrogénation

Practical (asymmetric) transfer hydrogenation of ketones catalyzed by manganese with (chiral) diamines ligands

International audienceThe reduction of ketones with 2-propanol as reductant was achieved using an in-situ generated catalytic system based on manganese pentacarbonyl bromide, as metal precursor, and ethylenediamine as ligand. The reaction proceeds in high yield at 80 °C, in 3 h, with 0.5 mol% of catalyst. In the presence of chiral (1R,2R)-N,N′-dimethyl-1,2-diphenylethane-1,2-diamine, as the ligand, sterically hindered alcohols were produced with enantiomeric excess up to 90%

Copper-Catalyzed Carbonylative Cross-Coupling of Alkyl Iodides and Amines

A general copper-catalyzed carbonylative cross-coupling between amines and alkyl iodides is reported. Using a simple combination of catalytic amounts of copper(I) chloride and N,N,N’,N”,N”-pentamethyldiethylenetriamine in the presence of sodium hydroxide under carbon monoxide pressure, a broad range of alkyl iodides and amines can be efficiently coupled to the corresponding amides that are obtained in good to excellent yields. Notable features of this process – the first one relying on a base metal catalyst – include the availability and low cost of the catalytic system, its successful use with primary, secondary, tertiary alkyl iodides and all classes of amines – with no or limited competing nucleophilic substitution without CO incorporation – as well as its efficiency with complex alkyl iodides and amines. Mechanistic studies demonstrated that a radical pathway is operative and the key role of CO.info:eu-repo/semantics/publishe

Copper-Catalyzed Carbonylative Cross-Coupling of Alkyl Iodides with Alcohols and Sodium Hydroxide: Synthesis of Esters and Carboxylic Acids

A general and inexpensive catalytic system is reported for the copper-catalyzed carbonylative coupling between alkyl iodides and alcohols or sodium hydroxide. Upon reaction with catalytic amounts of copper(I) chloride and N,N,N’,N”,N”-pentamethyldiethylenetriamine under a mild pressure of carbon monoxide (5 bar), a range of secondary and tertiary alkyl iodides are readily converted to the corresponding esters and carboxylic acids without competing direct nucleophilic substitution. Main advantages of this procedure include its broad applicability, the use of an especially inexpensive and available catalytic system and its user-friendliness.info:eu-repo/semantics/publishe

Hydrogenation of ketones with a manganese PN3P pincer pre-catalyst

International audienceA catalytic hydrogenation of carbonyl derivs. with a manganese pre-catalyst has been developed. The key feature is the use of an air stable cationic manganese pre-catalyst bearing a tridendate ligand with a 2,6-(diaminopyridinyl)diphosphine scaffold. Under 50 bar of H2, at 130°, various ketones were reduced to the corresponding alcs. with moderate to good yield

Manganese catalyzed reductive amination of aldehydes using hydrogen as a reductant

International audienceA one-pot two-step procedure was developed for the alkylation of amines via reductive amination of aldehydes using molecular dihydrogen as a reductant in the presence of a manganese pyridinyl-phosphine complex as a pre-catalyst. After the initial condensation step, the reduction of imines formed in situ is performed under mild conditions (50-100 degrees C) with 2 mol% of catalyst and 5 mol% of tBuOK under 50 bar of hydrogen. Excellent yields (>90%) were obtained for a large combination of aldehydes and amines (40 examples), including aliphatic aldehydes and amino-alcohols

Manganese catalyzed α-methylation of ketones with methanol as a C1 source

International audienceThe direct α-methylation of ketones with methanol under hydrogen borrowing conditions using a well-defined manganese PN3P complex as a pre-catalyst was, for the first time, achieved. The reactions typically proceed at 120 °C for 20 h with 3 mol% pre-catalyst loading and in the presence of NaOtBu (50 mol%) as base. The scope of the reaction was extended to the α-methylation of esters

Asymmetric transfer hydrogenation of ketones promoted by manganese(I) pre-catalysts supported by bidentate aminophosphines

International audienceA series of commercially available chiral amino-phosphines, in combination with Mn(CO)5Br, has been evaluated for the asymmetric reduction of ketones, using isopropanol as hydrogen source. With the most selective ligand, the corresponding manganese complex was synthesized and fully characterized. A series of ketones (20 examples) was hydrogenated in the presence of 0.5 mol% of the manganese pre-catalyst at 30 °C, affording the chiral alcohols in high yields with enantiomeric excesses up to 99%

Manganese-Catalyzed Transfer Hydrogenation of Aldimines

International audienceThe reduction of imines to amines via transfer hydrogenation was achieved promoted by phosphine‐free manganese(I) catalyst. Using isopropanol as reductant, in the presence of tBuOK (4 mol %) and manganese complex [Mn(CO)3Br(κ2N,N‐PyCH2NH2)] (2 mol %), a large variety of aldimines (30 examples) were typically reduced in 3 hours at 80 °C with good to excellent yield