Synchronizing Steric and Electronic Effects in {Ru II (NNNN,P)} Complexes: The Catalytic Dehydrative Alkylation of Anilines by Using Alcohols as a Case Study

Synthesis and catalytic activity of well-defined Co(I) complexes based on NHC-phosphane pincer ligands

A new methodology for the preparation of Co(I)-NHC (NHC = N-heterocyclic carbene) complexes, namely, [Co(PCNHCP)(CO)2][Co(CO)4] (1) and [Co(PCNHCP)(CO)2]BF4 (2), has been developed (PCNHCP = 1,3-bis(2-(diphenylphosphanyl)ethyl)-imidazol-2-ylidene). Both complexes can be straightforwardly prepared by direct reaction of their parent imidazolium salts with the Co(0) complex Co2(CO)8. Complex 1 efficiently catalyses the reductive amination of furfural and levulinic acid employing silanes as reducing agents under mild conditions. Furfural has been converted into a variety of secondary and tertiary amines employing dimethyl carbonate as the solvent, while levulinic acid has been converted into pyrrolidines under solventless conditions. Dehydrocoupling of the silane to give polysilanes has been observed to occur as a side reaction of the hydrosilylation process.

Copper-catalyzed three-component N-alkylation of quinazolinones and azoles

A Cu-catalyzed three-component N-alkylated coupling reaction of N-heteroarenes with methyl ketones and one carbon source has been developed. Using methyl ketones as alkylation reagent and DMPA (N,N’-dimethylpropionamide) as one carbon...

Base-Free Synthesis of Furfurylamines from Biomass Furans Using Ru Pincer Complexes

We report the first example of employing homogeneous organometal-catalyzed transfer hydrogenation for the selective reductive amination of furfurals to furfurylamines. An efficient, chemoselective, and base-free method is described using Ru-MACHO-BH as catalyst and iPrOH as H donor. The method tolerates a range of substituents affording moderate to excellent yields.

Brønsted acid/visible-light-promoted Markovnikov hydroamination of vinylarenes with arylamines

A Brønsted acid/visible-light-promoted Markovnikov hydroamination of vinylarenes with arylamines in the presence of TPT and CF₃CO₂H has been developed. This transformation provides a green approach to alpha-amino-substituted arylalkanes under metal-free conditions.

The N-alkylation of sulfonamides with alcohols in water catalyzed by a water-soluble metal–ligand bifunctional iridium complex [Cp*Ir(biimH2)(H2O)][OTf]2

A water-soluble dinuclear Cp*Ir complex bearing 4,4′,6,6′-tetrahydroxy-2,2′-bipyrimidine as a bridging ligand was found to be a highly effective catalyst for the N-alkylation of ketones with alcohols in water.

A General Palladium-Phosphine Complex To Explore Aryl Tosylates in the N-Arylation of Amines: Scope and Limitations

The scope and limitations of the monoselective N-arylation of various amines by using aryl and hetaryl tosylates are presented. The air-stable and easily accessible Pd(OAc)₂ /CM-phos {CM-phos=2-[2-(dicyclohexylphosphino)phenyl]-1-methyl-1H-indole}catalyst system was able to deal with a wide range of aryl tosylate substrates as well as amine nucleophiles, including primary and secondary cyclic/acyclic aliphatic amines and anilines. NH-Bearing heterocycles such as indole, carbazole, pyrrole, 10-phenothiazine, and 10-phenoxazine were shown to be feasible coupling partners under this catalytic system. The described reaction conditions tolerate a wide range of functional groups and allow an array of aromatic amines as well as unsymmetrical amine products to be easily accessed from the various phenolic derivatives. Interestingly, this catalyst system even offers the opportunity to perform the reaction in water medium. We also report the intermolecular coupling of optically active α-central chiral amines with aryl tosylates without erosion of the enantiomeric purity.

Facile access to N-substituted anilines via dehydrogenative aromatization catalysis over supported gold–palladium bimetallic nanoparticles

In the presence of a gold–palladium alloy nanoparticle catalyst (Au–Pd/Al₂O₃) and styrene, various kinds of structurally diverse N-substituted anilines (twenty three examples) could be synthesized starting from cyclohexanones and amines.

Intermolecular hydroaminoalkylation of alkenes and dienes using a titanium mono(formamidinate) catalyst

An easily accessible formamidinate ligand-bearing titanium complex initially synthesized by Eisen et al. is used as catalyst for intermolecular hydroaminoalkylation reactions of unactivated, sterically demanding 1,1- and 1,2-disubstituted alkenes and styrenes with secondary amines. The corresponding reactions, which have never been achieved with titanium catalysts before, take place with excellent regioselectivity (up to 99 : 1) and in addition, corresponding reactions of 1,3-butadienes with N-methylbenzylamine are also described for the first time.

Palladium-catalyzed reductive coupling of phenols with anilines and amines: efficient conversion of phenolic lignin model monomers and analogues to cyclohexylamines

A highly efficient Pd-catalyzed direct coupling of phenolic lignin model monomers and analogues with anilines to give cyclohexylamines using sodium formate as hydrogen donor is described.

Phenols, being readily available from naturally abundant lignins, are important future feedstocks for the renewable production of fuels, chemicals, and energy. Herein, a highly efficient Pd-catalyzed direct coupling of phenolic lignin model monomers and analogues with anilines to give cyclohexylamines using cheap and safe sodium formate as hydrogen donor is described. A variety of secondary and tertiary substituted cyclohexylamines can be synthesized under convenient conditions in moderate to excellent yields.

Benzimidazolin-2-ylidene N-heterocyclic carbene complexes of ruthenium as a simple catalyst for the N-alkylation of amines using alcohols and diols

Simple non-chelating ruthenium benzimidazolin-2-ylidene complexes as efficient N-alkylation catalysts using alcohols and diols following a hydrogen borrowing strategy.

Supported gold–palladium alloy nanoparticle catalyzed tandem oxidation routes to N-substituted anilines from non-aromatic compounds

In the presence of a supported gold–palladium alloy nanoparticle catalyst (Au–Pd/Al₂O₃), various kinds of N-substituted anilines can be synthesized from non-aromatic compounds.

Ruthenium-catalyzed N-alkylation of amines with alcohols under mild conditions using the borrowing hydrogen methodology

Using a simple amino amide ligand, ruthenium-catalyzed one-pot alkylation of primary and secondary amines with simple alcohols was carried out under a wide range of conditions. Using the alcohol as solvent, alkylation was achieved under mild conditions, even as low as room temperature. Reactions occurred with high conversion and selectivity in many cases. Reactions can also be carried out at high temperatures in organic solvent with high selectivity using stoichiometric amounts of the alcohol.

Selective transfer hydrogenation and hydrogenation of ketones using a defined monofunctional (P^N(Bn)^N(Bn)^P)-Ru(II) complex

A defined (P^N^N^P)-Ru complex possessing tertiary amines within the ligand backbone proved to be highly active both in transfer hydrogenations and hydrogenations of a variety of ketones. As compared to the existing catalytic systems, no bifunctional activation of H2 or of the substrate by the metal center and a secondary amine within the ligand backbone is required to obtain high activities at catalyst loadings of down to 10 ppm.