Iodide Anion Enables a Reductive Cross-Electrophile Coupling for Preparing Tertiary Amines

The reducing power of iodide anion is an underexplored property that can be used for the cross-electrophile coupling of organic molecules. Herein we harness this trait for the preparation of tertiary amines through the combination of two simple reagents: an electrophilic-carbon precursor and an iminium iodide in a dual role - both as nitrogen-containing building block and as reducing agent. The underlying mechanism of this new C-C bond-formation paradigm is explored through a combination of experiment and quantum chemical calculations.

Copper-catalysed chemoselective C-OH bond activation of N-benzoyl cytosine: facile access to 2-(dimethylamino)pyrimidine

A novel method for the direct amination of N-benzoyl cytosine has been developed, giving access to 2-(dimethylamino)pyrimidine derivatives. A copper(II) catalyst and tert-butyl hydroperoxide easily promote the selective amination process that proceeds via C-OH bond activation. This practical approach can utilize different formamide molecules, N,N-dimethylformamide and N,N-diethylformamide, as efficient amino (-NMe₂, -NEt₂) sources. Moreover, the facile nature of the procedure, its broad tolerance of aliphatic and aromatic substrates, the high yields and ease of separation of the products, and the fact that it can be conducted under aerobic conditions are all notable advantages of the present protocol.

Cobalt-Catalyzed Chemoselective Reduction of N-Heteroaryl Ketones with N,N-Dimethylformamide as a Hydride Source

A method for chemoselective reduction of 2-pyridyl ketones and related N-heteroaryl compounds catalyzed by cobalt stearate using DMF as a hydride source is developed. The ketone substrate is activated by chelation with cobalt, which makes the present method highly chemoselective. A possible reaction mechanism is proposed on the basis of control experiments.

A Brief Review: Advancement in the Synthesis of Amine through the Leuckart Reaction

This review presents a summary of reactions that take place during the “Leuckart-type reaction”. The significance of, as well as recent advancements in, the synthesis of amines through simple and inexpensive methods using readily available raw materials is discussed. This review includes all catalytic and noncatalytic reactions that involve the Leuckart method. Recent studies have shown that at least a quarter of C–N bond-forming reactions in the pharmaceutical industry are occur with the support of reductive amination. Recently, experimental conditions have achieved excellent yields. The “Leuckart-type reaction” is technically associated with Eschweiler–Clarke methylation. Compounds are grouped in accordance with the precept of action. This includes drugs affecting the central nervous system, cardiovascular system and gastrointestinal tract; anticancer drugs, antibiotics, antiviral and antifungal drugs; drugs affecting anxiety; convulsant, biotic, and HIV drugs; and antidiabetic drugs. Therefore, this review supports the development of the Leuckart-type preparation of nitrogenous compounds, as well as their advancement in other areas of human development.

Room-Temperature Dialkylamination of Chloroheteroarenes Using a Cu(II)/PTABS Catalytic System

The dimethylamino functionality has significant importance in industrially relevant molecules and methodologies to install these efficiently are highly desirable. We report herein a highly efficient, room-temperature dimethylamination of chloroheteroarenes performed via the in-situ generation of dimethylamine using N,N-dimethylformamide (DMF) as precursor wiith a large substrate scope that includes various heteroarenes, purines as well as commercially relevant drugs such as altretamine, ampyzine and puromycin precursor.

Zirconium-Based Catalysts in Organic Synthesis

Zirconium is a silvery-white malleable and ductile metal at room temperature with a crustal abundance of 162 ppm. Its compounds, showing Lewis acidic behavior and high catalytic performance, have been recognized as a relatively cheap, low-toxicity, stable, green, and efficient catalysts for various important organic transformations. Commercially available inorganic zirconium chloride was widely applied as a catalyst to accelerate amination, Michael addition, and oxidation reactions. Well-designed zirconocene perfluorosulfonates can be applied in allylation, acylation, esterification, etc. N-Chelating oganozirconium complexes accelerate polymerization, hydroaminoalkylation, and CO₂ fixation efficiently. In this review, the applications of both commercially available and synthesized zirconium catalysts in organic reactions in the last 5 years are highlighted. Firstly, the properties and application of zirconium and its compounds are simply introduced. After presenting the superiority of zirconium compounds, their applications as catalysts to accelerate organic transformations are classified and presented in detail. On the basis of different kinds of zirconium catalysts, organic reactions accelerated by inorganic zirconium catalysts, zirconium catalysts bearing Cp, and organozirconium catalysts without Cp are summarized, and the plausible reaction mechanisms are presented if available.

Aerobic Allylic Amination Catalyzed by a Pd(OAc)2/P(OPh)3 System with Low Catalyst Loading

A Pd(OAc)₂/P(OPh)₃ combination catalyzed Tsuji-Trost-type allylic amination under aerobic conditions. Both aromatic and aliphatic secondary amines were transformed into the corresponding allylic amines with a tiny amount of the catalyst system (typically 0.02 mol % Pd), only when allylic phosphates were employed as electrophiles. Other typical electrophiles, such as allylic acetate and carbonate, were marginally reactive. A Pd(0) complex, Pd[P(OPh)₃]₃, formed in situ was suggested as an active species by mechanistic experiments.

One catalyst for two uses: TiOx–C acts as either a photocatalyst or thermocatalyst to promote reductive amination

Titanium oxide uniformly doped with carbon (TiOx–C) efficiently promotes the reductive amination of aliphatic aldehydes as a catalyst not only under visible light but also under heating conditions.

A Journey from June 2018 to October 2021 with N,N-Dimethylformamide and N,N-Dimethylacetamide as Reactants

A rich array of reactions occur using N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMAc) as reactants, these two amides being able to deliver their own H, C, N, and O atoms for the synthesis of a variety of compounds. This account highlights the literature published since June 2018, completing previous reviews by the author.

Earth-abundant Metal-catalyzed Reductive Amination: Recent Advances and Prospect for Future Catalysis

Nitrogen-containing compounds, as an important class of chemicals, have been used widely in pharmaceuticals, materials synthesis. Transition metal-catalyzed reductive amination of an aldehyde or a ketone with ammonia or an amine has been proved to be an efficient and practical method for the preparation of nitrogen-containing compounds in academia and industry for a century. Given the above, several effective methods using transition metals have been developed in recent years. Noble transition metals like Pd, Pt, and Au-based catalysts have been predominately used in reductive amination. Because of their high prices, strict official regulations of residues in pharmaceuticals, and deleterious effects on the biological system, their industrial applications are severely hampered. With the increasing sustainable and environmental problems, the Earth-abundant transition metals including Ti, Fe, Co, Ni, and Zr have also been investigated for the reductive amination reaction and showed great potential to the advancement of sustainable and cost-effective reductive amination processes. This critical review will mainly summarize the work using Earth-abundant metals. The effects of different transition metals used in catalytic reduction amination were discussed and compared, and some suggestions were given. The last section highlights the catalytic activities of bi- and tri-metallic catalysts. Indeed, this latter family is very promising and simultaneously benefits from increased stability, and selectivity, compared to monometallic NPs, due to synergistic substrate activation. Few comprehensive reviews focusing on Earth-abundant transition metals catalyst has been published since 1948, although several authors reported some summaries dealing with one or the other part of this aspect. It is hoped that this critical review will inspire researchers to develop new efficient and selective earth-abundant metal catalysts for highly, environmentally sustainable reductive amination methods, as well as improve the pharmaceutical industry and related chemical synthesis company traditional method with the utilization of the green method widely.

Zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source

The zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source and zinc as reductant was successfully conducted. The presented method provides a low-cost, environmentally friendly and practical preparation of α-aryl amino esters, α-hydroxyketones and phenylethylenes. By using D2O as deuterium source, the corresponding products were obtained in high efficiency with excellent deuterium incorporation rate, which gives a cheap and safe tool for access to valuable deuterium-labelled compounds.

Synthesis of tertiary amines by direct Brønsted acid catalyzed reductive amination

Tertiary amines are ubiquitous and valuable compounds in synthetic chemistry, with a wide range of applications in organocatalysis, organometallic complexes, biological processes and pharmaceutical chemistry. One of the most frequently used pathways to synthesize tertiary amines is the reductive amination reaction of carbonyl compounds. Despite developments of numerous new reductive amination methods in the past few decades, this reaction generally requires non-atom-economic processes with harsh conditions and toxic transition-metal catalysts. Herein, we report simple yet practical protocols using triflic acid as a catalyst to efficiently promote the direct reductive amination reactions of carbonyl compounds on a broad range of substrates. Applications of this new method to generate valuable heterocyclic frameworks and polyamines are also included.

Copper-Catalyzed Oxidative Synthesis of α-Ketoamides from Aryl Methyl Ketones and N-Bromobutanimide Using N,N-Dimethylformamide as Dimethylamine Source

A novel and practical Cu(OAc)2-catalyzed oxidative synthesis of α-ketoamides from aryl methyl ketones and N-bromobutanimide (NBS) using N,N-dimethylformamide (DMF) as dimethylamine (HNMe2) source and solvent has been developed under mild conditions. DMF was used as a HNMe2 source and can be easily converted into HNMe2 by acid hydrolysis. The mechanistic studies indicate that Cu(OAc)2 plays a dual role in providing both catalyst and oxidant.

An in situ approach to functionalize metal–organic frameworks with tertiary aliphatic amino groups

Tertiary aliphatic amino modified UiO-67/66(Zr), IRMOF-n(Zn) and MIL-101(Fe) were synthesized by a facile and efficient one-pot strategy under the corresponding metal catalysis.

Synthesis of Guerbet ionic liquids and extractants as β-branched biosourceable hydrophobes

This study investigates the synthesis of β-branched amines and β-branched quaternary ammonium chloride ionic liquids as novel extractants. The synthesis methodology was tailored to facilitate the reaction scale-up and the use of biorenewable starting materials. The developed process is an overall green, easy and straightforward synthesis of β-branched amines, and ammonium salts, starting from linear aldehydes. In order to evaluate the potential of the synthesised materials in applications, the rheology, density, thermal stability, chemical stability, phase transitions, and mutual solubility with water of the novel extractants was studied.

DMF/NaOH/H2O: a metal-free system for efficient and chemoselective reduction of α-ketoamides

A metal-free method for efficient and chemoselective reduction of α-ketoamides using DMF/NaOH/H₂O system has been developed.

Electrolysis promoted reductive amination of electron-deficient aldehydes/ketones: a green route to the racemic clopidogrel

An electrocatalytic reductive amination of electron-deficient aldehydes/ketones was developed, which could be used in the synthesis of functionalized tertiary amines and large scale preparation of racemic clopidogrel. A plausible mechanism involving an iminium cation intermediate was proposed.

The sustainable heterogeneous catalytic reductive amination of lignin models to produce aromatic tertiary amines

A sustainable and heterogeneous catalytic reductive amination process is developed in the presence of heterogeneous zirconium-based catalysts, in which N,N-dimethylformamide (DMF) is used as the solvent, the low-molecular-weight amine source, and the reductant.