Reductive Amination Of Carbonyl Compounds Research Articles

Hydrogen-Bond-Mediated Formation of C-N or C=N Bond during Photocatalytic Reductive Coupling Reaction over CdS Nanosheets.

Reductive amination of carbonyl compounds and nitro compounds represents a straightforward way to attain imines or secondary amines, but it is difficult to control the product selectivity. Herein, we report the selective formation of C-N or C=N bond readily manipulated through a solvent-induced hydrogen bond bridge, facilitating the swift photocatalytic reductive coupling process. The reductive-coupling of nitro compounds with carbonyl compounds using formic acid and sodium formate as the hydrogen donors over CdS nanosheets selectively generates imines with C=N bonds in acetonitrilesolvent; while taking methanol as solvent, the C=N bonds are readily hydrogenated to the C-N bonds viahydrogen-bonding activation. Experimental and theoretical study reveals that the building of the hydrogen-bond bridge between the hydroxyl groups in methanol and the N atoms of the C=N motifs in imines facilitates the transfer of hydrogen atoms from CdS surface to the N atoms in imines upon illumination, resulting in the rapid hydrogenation of the C=N bonds to give rise to the secondary amines with C-N bonds. Our method provides a simple way to control product selectivity by altering the solventsin photocatalytic organic transformations.

Electron-Rich Ru Supported on N-Doped Coffee Biochar for Selective Reductive Amination of Furfural to Furfurylamine.

Highly selective synthesis of primary amines from renewable biomass has attracted increasing attention, but it still faces great challenges in chemical industry applications. In this study, an electron-rich Ru catalyst was constructed by doping N into coffee biochar using a one-pot carbonization method (Ru/NCB-600). Ru/NCB-600 showed high catalytic activity and yield for the reductive amination of furfural with green and cheap NH3 and H2. The excellent catalytic performance of Ru/NCB-600 was closely correlated to the formation of electron-rich Ruδ- species (Ruδ--Nxδ+), which endowed Ru/NCB-600 with an enhanced H2 adsorption and activation ability. Ru/NCB-600 showed a high formation rate of 95.6 gfurfurylamine·gRu-1·h-1 and a high yield of furfurylamine (98.6%) at 50 °C. Ru/NCB-600 can also be used for the reductive amination of various carbonyl compounds in good to excellent yield (95.4-99%). This study thus provides a potential pathway for the highly selective reductive amination of carbonyl compounds by regulating the electron density of Ru.

Air-Stable and Highly Active Transition Metal Phosphide Catalysts for Reductive Molecular Transformations

This review introduces transition metal phosphide nanoparticle catalysts as highly efficient and reusable heterogeneous catalysts for various reductive molecular transformations. These transformations include the hydrogenation of nitriles to primary amines, reductive amination of carbonyl compounds, and biomass conversion, specifically, the aqueous hydrogenation reaction of mono- and disaccharides to sugar alcohols. Unlike traditional air-unstable non-precious metal catalysts, these are stable in air, eliminating the need for strict anaerobic conditions or pre-reduction. Moreover, when combined with supports, metal phosphides exhibit significantly enhanced activity, demonstrating high activity, selectivity, and durability in these hydrogenation reactions.

Valorization of Lignocellulosic Molecules through Homogeneous Ru‐Catalyzed C−C and C−N Bond Forming Reactions

AbstractA sustainable upgrading of renewable bulk materials, obtained by decomposition of biomass lignocellulose, could facilitate their use in the industrial production of chemicals. Homogeneous ruthenium catalysis plays a fundamental role in this area. The review deals with the upgradation of lignocellulosic molecules through the formation of new C−C and C−N bonds. Selected examples of catalytic bond forming reactions reported until mid of 2023, include: (a) dehydrogenative based couplings of alcohols, (b) reductive amination of carbonyl compounds, (c) direct C−H functionalization of (hetero)aromatic compounds. These approaches fulfill the requirements of sustainability: application occurs without any previous substrate activation, thus reducing the production of waste. New chemicals containing the intrinsic molecular structure of lignocellulose substrates, showed a broad range of applications: green fuels, hydrogen carriers, monomers of polymers, intermediates of fine chemicals and pharmaceuticals. The results discussed in the review could inspire the reader to improve the valorization process, in terms of bio‐substrate scope as well as product complexity, through more strategic applications of the catalytic methods.

Supported Ruthenium catalysts with electronic effect and acidity-basicity for efficient reductive amination of biomass-based carbonyl compounds

The efficiently reductive amination of carbonyl compounds to the corresponding primary amines under mild condition with NH3 and H2 as nitrogen and hydrogen sources is a challenging task in the chemistry community. Therefore, supported Ru catalysts with excellent catalytic activity for reductive amination of carbonyl compounds were synthesized in this work using a simple impregnation method. Among them, Ru/SBA-15 showed excellent catalytic performance for reductive amination of carbonyl compounds, and the yields were more than 91%. The Ru nanoparticles (Ru NPs) were uniformly dispersed on the support, and the structure of the support was not destroyed. The acidity-basicity and the appropriate electron density are the reasons for the high activity and selectivity of supported Ru catalysts. The catalyst design concept with both electronic effect and acidity-basicity combination provides a new strategy for the conversion of biomass-based carbonyl compounds.

General synthesis of secondary imines via reductive coupling of carbonyl and nitro compounds employing a reusable cobalt catalyst

Reusable nitrogen-doped carbon-encapsulated Co nanoparticle catalysts are found robust for the synthesis of secondary imines via the reductive amination of carbonyl compounds with NH3 or directly with nitro compounds.

Direct Synthesis of N-formamides by Integrating Reductive Amination of Ketones and Aldehydes with CO2 Fixation in a Metal-Organic Framework.

Formamides are important feedstocks for the manufacture of many fine chemicals. State-of-the-art synthesis of formamides relies on the use of an excess amount of reagents, giving copious waste and thus poor atom-economy. Here, we report the first example of direct synthesis of N-formamides by coupling two challenging reactions, namely reductive amination of carbonyl compounds, particularly biomass-derived aldehydes and ketones, and fixation of CO2 in the presence of H2 over a metal-organic framework supported ruthenium catalyst, Ru/MFM-300(Cr). Highly selective production of N-formamides has been observed for a wide range of carbonyl compounds. Synchrotron X-ray powder diffraction reveals the presence of strong host-guest binding interactions via hydrogen bonding and parallel-displaced π⋅⋅⋅π interactions between the catalyst and adsorbed substrates facilitating the activation of substrates and promoting selectivity to formamides. The use of multifunctional porous catalysts to integrate CO2 utilisation in the synthesis of formamide products will have a significant impact in the sustainable synthesis of feedstock chemicals.

Easy Access to Tertiary Amines from Carbonyl Compounds with Substituted Amine-Boranes: A Substrate, Catalyst, and Additive Free Approach Under Mild Conditions.

Tertiary amines are ubiquitous and play an essential role in organocatalysis, pharmaceuticals, and fine chemicals. Amongst various synthetic procedures known for their synthesis, the reductive amination of carbonyl compounds has been found to be a proficient method. Over the past few decades, different synthetic strategies for reductive amination have been developed. Most of them suffer from the use of transition metals and/or harsh reaction conditions. Herein, we present an efficient, operationally simple protocol for the chemoselective transformation of carbonyl compounds to tertiary amines under benign conditions. The strategy encompasses broad substrate scope under the metal-free condition at room temperature and does not require any solvent. A detailed mechanistic investigation was performed with the aid of control experiments and computational study to shed light on the reaction pathway.

Continuous reductive amination of carbonyl compounds with ammonia to synthesize secondary amines with high selectivity

Secondary amines are important compounds in the field of drug development. Applying reductive amination can conveniently synthesize secondary amines from carbonyl compounds. In this work, we propose an economical method for selective synthesis of secondary amines by using ammonia as a nitrogen source. A promising Pt/SiO2 (Pt loading 1 wt%) catalyst was designed for the continuous reductive amination of benzaldehyde (benchmark reaction), and effects of catalyst, solvent, temperature, the molar ratio of ammonia to benzaldehyde, pressure, concentration, liquid flow rate and gas flow rate are investigated. With the optimal reaction conditions, a high yield of dibenzylamine (95.5%) is obtained under very mild reaction temperature (30 ℃) and extremely short reaction times. Furthermore, a kinetic model for the formation of dibenzylamine is established, and corresponding kinetic parameters are obtained. Besides, many substrates, including aromatic aldehydes, biomass derivative furfural and even ketone, can all be smoothly converted into secondary amines.

Carbon Nitride Nanosheet-Supported Bismuth Nanoparticle Catalyst for Reductive Amination of Carbonyl Compounds with Nitroaromatics

Carbon Nitride Nanosheet-Supported Bismuth Nanoparticle Catalyst for Reductive Amination of Carbonyl Compounds with Nitroaromatics

Promoting Amination of Furfural to Furfurylamine by Metal-support Interactions on Pd/MoO3-x Catalysts.

The reductive amination of carbonyl compounds is one of the most straightforward protocols to construct C-N bonds, but highly desires active and selective catalysts. Herein, Pd/MoO3-x catalysts are proposed for furfural amination, in which the interactions between Pd nanoparticles and MoO3-x supports can be easily ameliorated via varying preparation temperature toward efficient catalytic turnover. Thanks to the synergistic cooperation of MoV-rich MoO3-x and highly-dispersed Pd, the optimal catalysts afford the high yield of furfurylamine (84%) at 80 oC. Thereinto, MoV species not only acts as the acidic promoter to facilitate the activation of carbonyl groups, but also interacts with Pd nanoparticles to promote the subsequent hydrogenolysis of Schiff base N-furfurylidenefurfurylamine and its germinal diamine. The good efficiency of Pd/MoO3-x within a broad substrate scope further highlights the key contribution of metal-support interactions to the refinery of biomass feedstocks.

One-pot protocol for the reductive amination of aldehydes using thiamine hydrochloride as a green catalyst under solvent-free condition

A novel, green, solvent-free, and efficient method has been developed for the one-pot reductive amination of carbonyl compounds using thiamin hydrochloride as a catalyst. This method has performed reductive amination on various functionalized amines and aldehydes, including aliphatic, aromatic, and heteroaromatic ones. The reductive amination of the carbonyl compounds occurred in a single step without any side reaction. The key benefits of this technique included its easiness, greener protocol, quick transformation, variety of substrates, outstanding yield, metal-free, and catalyst recyclability. This helps to make the procedure practical, affordable, and biodegradable.

Ruthenium‐Catalyzed Direct Reductive Amination of Carbonyl Compounds for the Synthesis of Amines: An Overview

AbstractReductive amination is a valuable method for amine synthesis that has been the topic of a century‘s worth of in‐depth study in both academia and industry. Amines and their derivatives serve as incredibly adaptable building blocks for a broad array of organic substrates and are significant precursors for a myriad of advanced chemicals, physiologically active compounds, agrochemicals, biomolecules, pharmaceuticals, and polymers. The creation of innovative catalytic processes for the long‐term and selective synthesis of amines from readily accessible and environmentally benign reagents remains a top priority in chemical research. Both heterogeneous and homogeneous catalysts have been designed with success to enable these reactions to explore new amines. Ruthenium catalysts are employed in reductive amination owing to their stability, selectivity, versatility, low toxicity, and high efficiency. This review comprehensively overviews the Ru‐catalyzed reductive amination processes and includes the literature from 2009 to 2022.

Discovery of an Imine Reductase for Reductive Amination of Carbonyl Compounds with Sterically Challenging Amines.

The synthesis of structurally diverse amines is of fundamental significance in the pharmaceutical industry due to the ubiquitous presence of amine motifs in biologically active molecules. Biocatalytic reductive amination for amine production has attracted great interest owing to its synthetic advantages. Herein, we report the direct synthesis of a wide range of sterically demanding secondary amines, including several important active pharmaceutical ingredients and pharmaceutical intermediates, via reductive amination of carbonyl substrates and bulky amine nucleophiles employing imine reductases. Key to success for this route is the identification of an imine reductase from Penicillium camemberti with unusual substrate specificity and its further engineering, which empowered the accommodation of a broad range of sterically demanding amine nucleophiles encompassing linear alkyl and (hetero)aromatic (oxy)alkyl substituents and the formation of final amine products with up to >99% conversion. The practical utility of the biocatalytic route has been demonstrated by its application in the preparative synthesis of the anti-hyperparathyroidism drug cinacalcet.

One-pot reductive amination of carbonyl compounds and nitro compounds via Ir-catalyzed transfer hydrogenation.

The formation of C-N bond is a vital synthetic tool for establishing molecular diversity, which is highly sought after in a wide range of biologically active natural products and drugs. Herein, we present a new strategy for the synthesis of secondary amines via iridium-catalyzed one-pot reductive amination of carbonyl compounds with nitro compounds. This method is demonstrated for a variety of carbonyl compounds, including miscellaneous aldehydes and ketones, which are compatible with this catalytic system, and deliver the desired products in good yields under mild conditions. In this protocol, the reduction of nitro compounds occurs in situ first, followed by reductive amination to form amine products, providing a new one-pot procedure for amine synthesis.

Sodium hypophosphite mediated reductive amination of carbonyl compounds with N,N-dialkylformamides

Herein we report a transition-metal- and acid-free protocol for the reductive amination of carbonyl compounds with DMF using a substoichiometric amount of NaH2PO2·H2O. The general trends and limitations of the method were explored.

Ionic polyamide boosting Ru efficiency in reductive amination of carbonyl compounds

Ionic polyamide-stabilized ruthenium nanoparticles for ultra-efficient reductive amination of carbonyl compounds to primary amines with NH3 and H2.

Selectivity tunable iron nanoparticles from lignocellulosic components for the reductive amination of carbonyl compounds towards switchable products

The regulatory mechanism of reductive amination by selectivity tunable iron nanoparticles, which enables the synthesis of various products from carbonyl compounds with excellent efficiency, was explored.

Palladium nanocatalyst assisted in situ regeneration of amino donor in a one-enzyme cascade

α-Chiral amines are key intermediates for scalable preparation of bioactive compounds; herein we present a novel palladium-based nanocatalyst capable of selectively catalyzing the reductive amination of carbonyl compounds, which enables the in situ regeneration of amino donors from wasteful co-products in a one-enzyme cascade using ω-transaminase, without the requirement of the expensive coenzyme NAD(P)H.

Reductive Amination of Carbonyl Compounds over a Ni2P/SiO2 Catalyst in a Flow Mode

Reductive Amination of Carbonyl Compounds over a Ni2P/SiO2 Catalyst in a Flow Mode