N-Alkylation of poor nucleophilic amine and sulfonamide derivatives with alcohols by a hydrogen autotransfer process catalyzed by copper(II) acetate

Direct Synthesis of Amides from Benzonitriles and Benzylic Alcohols via a KOt-Bu-Mediated MPV-type Hydrogen Transfer Process

Meerwein-Ponndorf-Verley (MPV)-type reduction between benzonitriles and benzylic alcohols under transition-metal-free conditions has been demonstrated for the first time. Using simple KOt-Bu as the base, various benzonitriles can be efficiently reduced by benzylic alcohols via hydrogen transfer reduction, and the resultant phenyl imine can react further with benzylic alcohols to give amides as the final product in which both the alcohols and the nitriles are incorporated. Preliminary mechanistic investigations indicated that the reaction may go through multiple MPV-type hydrogen transfer processes.

Solvent/metal-free benzimidazolium-based carboxyl-functionalized porphyrin photocatalysts for the room-temperature alkylation of amines under the irradiation of visible light

The improvement of novel sustainable catalytic methods for green chemical production is an emergent area in chemical science.

Visible-light-promoted iron catalyzed C‒H functionalization of 1,4-naphthoquinones via oxidative coupling with sulfoximines

A catalytic oxidative addition of sulfoximines to naphthoquinones via its C-H functionalization has been achieved using iron catalytic system, which exhibits good reactivity and high regioselectivity in presence of visible...

Synthesis and identification of heteroaromatic N-benzyl sulfonamides as potential anticancer agents

Sulfonamides are a crucial class of bioisosteres that are prevalent in a wide range of pharmaceuticals, however, the available methods for their production directly from heteroaryl aldehyde reagents remains surprisingly limited. A new approach for regioselective incorporation of a sulfonamide unit to heteroarene scaffolds has been developed and is reported within. As a result, a variety of primary benzylic N-alkylsulfonamides have been prepared via a two-step (one pot) formation from the in situ reduction of an intermediate N-sulfonyl imine under mild, practical conditions. The compounds have been screened against a variety of cell lines for cytotoxicity effects using a Cell Titer Blue assay. The cell viability investigation identifies a subset of N-benzylic sulfonamides derived from the indole scaffold to be targeted for further development into novel molecules with potential therapeutic value. The most cytotoxic of the compounds prepared, AAL-030, exhibited higher potency than other well-known anticancer agents Indisulam and ABT-751.

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.

N-Monomethylation of Aromatic Amines with Methanol via PNHP-Pincer Ru Catalysts

The use of methanol for the selective methylation of aromatic amines with RuHCl(CO)(PN^HP) (PN^HP = bis(2-diphenylphosphinoethyl)amine) is reported. Various aromatic amines were transformed into their corresponding monomethylated secondary amines in high yields at 150 °C with a very low catalyst loading (0.02-0.1 mol %) in the presence of KO ^tBu (20-60 mol %). The catalyst precursor, RuHCl(CO)(PN^HP), was converted to [RuH(CO)₂(PN^HP)]⁺ under the catalytic conditions and also serves as a highly effective catalyst. The robustness of this catalyst contributes to its outstanding catalytic activity, even under reaction conditions, in which CO is liberated from methanol.

Gold(I)/Gold(III)-Catalyzed Selective Synthesis of N-Sulfonyl Enaminone Isomers from Sulfonamides and Ynones via Two Distinct Reaction Pathways

Au-catalyzed chemoselective methods for synthesizing N-sulfonyl enaminones are developed. Two different isomers are obtained in a chemocontrolled manner by employing the different properties of Au(I) and Au(III) catalysts. Hydroamidation and proton-assisted carbonyl activation followed by Meyer-Schuster rearrangement are proposed as the working mechanisms for the reactions. A wide range of substrates afforded moderate to excellent yields and selectivities. These reactions represent the first examples of transition-metal-catalyzed enamine synthesis from sulfonamides and alkynes.

Hydrogen autotransfer and related dehydrogenative coupling reactions using a rhenium(i) pincer catalyst

A novel rhenium complex bearing a non-innocent PNP pincer ligand was prepared.

Iron-Mediated Annulation between Methylene Ketones and Diethanolamines: A Sustainable and Scalable Procedure toward N-(2-Hydroxyethyl) Pyrroles

An iron-mediated direct annulation between methylene ketones and diethanolamines was developed for the efficient synthesis of N-(2-hydroxyethyl) pyrroles. This protocol shows high efficiency, operational simplicity, good functional group compatibility as well as broad substrates scope.

Pd@[nBu₄][Br] as a Simple Catalytic System for N-Alkylation Reactions with Alcohols

Palladium nanoparticles, simply and briefly generated in commercial and cheap onium salts using supercritical carbon dioxide, have been found to be an effective catalytic system for additive free N-alkylation reaction using alcohols via cascade oxidation/condensation/reduction steps.

Ruthenium-Catalyzed Amination of Secondary Alcohols using Borrowing Hydrogen Methodology

A new ruthenium complex catalyzes the amination of primary and secondary alcohols and the regioselective mono- and sequential diamination of diols via the borrowing hydrogen pathway. Several variations on new intra- and intermolecular cyclizations of aminoalcohols, diols and diamines lead to heterocyclic ring systems.

Mechanistic insight into Cu/Ag-cocatalyzed C–H activation of arenes with oxygen as the terminal oxidant

The possible transition states of C–H activation on the dehydrogenate coupling of arenes with alcohols employing Ag(i) additives were investigated using B3LYP density functional theory.

Iron-catalyzed amination of alcohols assisted by Lewis acid

An efficient Lewis acid-assisted, iron-catalyzed amination of alcohols using borrowing hydrogen methodology was developed. In particular, silver fluoride was identified to be a highly effective additive to overcome the low efficiency in the amination of secondary alcohols catalyzed by Knölker's complex.

Carbon-catalysed reductive hydrogen atom transfer reactions

Generally, transition metal catalysts are essential for the reductive hydrogen atom transfer reaction, which is also known as the transfer hydrogenation reaction or the borrowing-hydrogen reaction. It has been reported that graphene can be an active catalyst in ethylene and nitrobenzene reductions, but no report has described carbon-based materials as catalysts for alcohol amination via the borrowing-hydrogen reaction mechanism. Here we show the results from the preparation, characterization and catalytic performance investigation of carbon catalysts in transition metal-free borrowing-hydrogen reactions using alcohol amination and nitro compound/ketone reduction as model reactions. XPS, XRD, SEM, FT-IR and N2 adsorption-desorption studies revealed that C=O group in the carbon catalysts may be a possible catalytically active site, and high surface area is important for gaining high activity. The activity of the carbon catalyst remained unchanged after reuse. This study provides an attractive and useful methodology for a wider range of applications.

Mechanistic study on the Cp*iridium-catalyzed N-alkylation of amines with alcohols

Using DFT methods and the energetic span model, the most favorable hydrogen autotransfer pathway for the [Cp*IrCl₂]₂/K₂CO₃-catalyzed N-alkylation of amines with alcohols has been found.

An efficient heterogenized palladium catalyst for N-alkylation of amines and α-alkylation of ketones using alcohols

Silica supported palladium–NiXantphos complex is an efficient and high turnover heterogeneous catalyst for N-alkylation of amines and α-alkylation of ketones using alcohols under neat conditions at 120–140 °C following hydrogen borrowing strategy.

A conjugated ketone as a catalyst in alcohol amination reactions under transition-metal and hetero-atom free conditions

A molecular-defined conjugated ketone can be an active catalyst for alcohol amination reactions with up to 98% isolated yields for the desired products.

Substitution of alcohols by N-nucleophiles via transition metal-catalyzed dehydrogenation

This review summarizes the recent advances in transition metal-catalyzed dehydrogenative substitution of alcohols by N-nucleophiles since 2009.

New iridium catalysts for the selective alkylation of amines by alcohols under mild conditions and for the synthesis of quinolines by acceptor-less dehydrogenative condensation

A novel family of iridium catalysts stabilised by P,N-ligands have been introduced. The ligands are based on imidazo[1,5-b]pyridazin-7-amines and can be synthesised with a broad variety of substitution patterns. The catalysts were synthesised quantitatively from the protonated ligands and a commercially available iridium precursor. The catalysts mediate the alkylation of amines by alcohols under mild conditions (70 °C). In addition, the synthesis of quinolines from secondary or primary alcohols and amino alcohols is reported. This sustainable synthesis proceeds through the liberation of two equivalents of water and two equivalents of dihydrogen. The investigations indicate that catalysts suitable for hydrogen autotransfer or borrowing hydrogen chemistry might also be suitable for acceptor-less dehydrogenative condensation reactions.

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.