Programmable Mono-/Di-alkylation of Amines with Aldehydes Over a Pdδ --H Electrocatalyst

Programmable amine N-alkylation provides a new method to combine the required alkyl groups with amine molecules according to actual demand and to precisely regulate the biological and pharmaceutical properties of life science amine molecules. However, only the electrochemical mono-methylation of amines has been achieved via C─N coupling with CO2 accompanied by an unsatisfactory Faraday efficiency (FE) lower than 10%. Herein, we developed programmable electrocatalytic N-alkylation of amines with two controllable alkyl groups and one methyl group. Both experimental characterization and density functional theory (DFT) calculations have demonstrated the critical role of electron-enriched Pd metals in transforming amines into alkylamines with two chosen alkyl groups and a methyl group. Moreover, the electrocatalytic transformation of amines to alkylamines with satisfactory FE values (86%-96%) has been achieved, further expanding the scope of electrochemical C─N coupling and possibly opening a new world of electrochemical amine N-alkylation.

Role of Spectator Species for Amine-Surface Chemistry: Reactions of Amines and Alkenes on Pt(111)

This study investigates the roles of ethylene and ethylidyne in the surface chemistry of N-methylaniline (NMA) on Pt(111). Using X-ray photoelectron spectroscopy, temperature-programmed desorption, and density functional theory calculations, we demonstrate that ethylidyne is not merely a passive spectator species but actively contributes to hydroamination. It facilitates C-N bond formation by transferring a methyl group to NMA, leading to the formation of N,N-dimethylaniline. Additionally, it stabilizes reaction intermediates and suppresses the decomposition of NMA. This works demonstrates, in contrast to the widely accepted notion, that ethylidyne is not just an inert spectator species; rather, it plays a dual role as both an active reaction partner and a stabilizer. In addition, the coadsorption of ethylene on an NMA-precovered surface shows a side reaction of ethylene with the decomposition products of NMA.

Phase-Separated Multienzyme Condensates for Efficient Synthesis of Imines from Carboxylic Acids with Enhanced Dual-Cofactor Recycling

Enzyme catalysis represents a promising approach for sustainable chemical synthesis, yet its industrial applications face limitations due to the inefficient regeneration and high cost of essential cofactors, such as adenosine-5'-triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). While natural metabolic systems efficiently recycle cofactors through spatially organized enzymes, replicating this efficiency in vitro remains challenging. Here, we prepare a five-enzyme condensate system using liquid-liquid phase separation (LLPS) mediated by intrinsically disordered proteins (IDPs). By colocalizing a carboxylic acid reductase from Norcadia iowensis (NiCAR) with a reductive aminase from Aspergillus oryzae (AspRedAm) and three cofactor-regenerating enzymes, we generated a phase-separated catalytic condensate that enhanced ATP and NADPH recycling efficiency by 4.7-fold and 1.9-fold relative to free enzymes, respectively. Catalytic performance was correlated with the extent of phase separation, as confirmed by fluorescence microscopy, which revealed clear enrichment of ATP and NADPH within the condensates. This proximity effect enabled efficient cofactor turnover in the one-step reaction, achieving substrate conversion above 90% within 6 h and enhancing the space-time yield (STY) of the chiral imines 1.6-fold, with only one-fifth of the standard cofactor load. This approach creates a scalable and economic tool for performing multienzyme cascade reactions in vitro that are driven by the efficient recycling of multiple cofactors.

Engineering Atomic Sites and Proton Transfer Microenvironments for Bioinspired Photocatalytic Alcohol-Amine Coupling

Achieving a precise understanding and accurate design of heterogeneous catalysts based on bioinspired principles is challenging yet crucial to digging out optimal materials for artificial catalysis. Here, an ADH-mimicking dual-site photocatalyst (YCuCdS) is developed, and demonstrates the powerful effects of atomic site configuration and proton transfer environments on alcohol-amine coupling. Mechanism studies reveal that the alcohol substrate is effectively dehydrogenated at the Y sites, forming the carbonyl intermediates that rapidly experience condensation with the amine. Meanwhile, the released hydrogen species (Hads) migrate from adjacent Cu sites to active S atoms, promoting H2 production and hindering the over-hydrogenation of imine. As a result, a high imine yield of 92% is achieved, along with an H2 production rate of 7400 µmol g-1 h-1. This work showcases an effective strategy for the design of heterogeneous catalysts with bioinspiration.

Recent developments in polymer chemistry, medicinal chemistry and electro-optics using Ni and Pd-based catalytic systems

Catalysis is the fastest and continuously growing field in chemistry. A key component of this process is catalytic systems, which result in increased reaction rates and yields, as well as the ability to tailor the properties of products to the final application. With the development of catalysis, the requirements for catalysts used in these processes have also grown rapidly. Modern catalytic materials should overcome the challenges posed by the modern world of chemistry. They should be durable, and stable, have good catalytic properties, and allow catalytic processes to be carried out under mild and environmentally friendly conditions. In this article, we provide an overview of recent reports on the use of catalytic systems based on nickel and palladium ions in catalytic reactions, leading to functional materials used in the fields of medicinal chemistry, polymer chemistry and electro-optical materials chemistry. Research on the optimization and modification of existing synthetic methods, reports on the synthesis of new functional materials, and articles on new, more efficient catalytic systems that overcome the drawbacks of existing catalysts are described. The presented article reviews current knowledge, providing the newest information from the world of catalysis and synthesis of advanced functional materials, presenting potential directions for further development in these fields.

Highly Active and Air-Stable Iron Phosphide Catalyst for Reductive Amination of Carbonyl Compounds Enabled by Metal-Support Synergy

Iron has long been recognized as an ideal catalytic material for sustainable chemistry. However, conventional iron catalysts employed in liquid-phase hydrogenation reactions suffer from poor activity and air instability, severely restricting their wide applicability in practical use. Herein, we present the development of highly active and air-stable iron phosphide nanocrystal immobilized on zirconia (Fe2P NC/ZrO2) for the reductive amination of aldehydes and ketones. The Fe2P NC/ZrO2 catalyst demonstrated broad substrate applicability, high recyclability, and scalability in both gram-scale and continuous-flow processes. This catalyst leverages the synergistic metal-support effect of Fe2P NCs and ZrO2 support, leading to activity 313 times higher than that of conventional iron nanoparticle catalysts. In-depth mechanistic studies elucidated that the distinctive interplay between Fe2P and ZrO2 significantly accelerates ammonolysis of Schiff bases, a key step for boosting reaction efficiency. This study sets a new benchmark for iron-based catalysis, offering a robust alternative to precious metals, thereby contributing significantly to sustainable chemical manufacturing and green organic synthesis.

Kinetic Resolution to Simultaneously Access Both Primary and Secondary NH-Unprotected Chiral Amines via Ir-Catalyzed Asymmetric Reductive Amination

This report describes a new kinetic resolution-asymmetric reductive amination strategy to collectively gain access to both primary and secondary chiral NH-unprotected amines. Catalyzed by the complex of iridium and bulky and tunable phosphoramidite ligands, various ketones and racemic primary amines could be smoothly converted to two different types of amine products. Bronsted acids as additives play triple roles, decreasing the inhibitory effect, promoting the formation of the imine intermediates, and guiding the reaction to proceed through "outer-sphere" H-addition along with the bulky ligand.

Rapid Fluorochromic Sensing of Tertiary Amines and Opioids via Dual-Emissive Ground and Excited Charge-Transfer States

The recognition and differentiation of organic amines are crucial for applications in drug analysis, food spoilage, biomedical assays, and clinical diagnostics. Existing luminescence-based recognition methods for amines predominantly rely on fluorescence quenching, limiting the scope of sensitive and selective detection. Here, we present a fluorochromic approach for rapidly distinguishing different organic amines based on their unique excited-state and ground-state interactions with a naphthalimide derivative under ultraviolet light. Our findings reveal that the photoluminescence quantum yield and emission color are significantly influenced by the substituent group and the molecular flexibility of the amine. Specifically, primary amines, together with other common lone-pair donors, such as alcohol, ether, thiol, thioether, and phosphine, did not exhibit photoluminescence changes, while secondary amines exhibited only weak emission. For tertiary amines, however, bright green photoluminescence activation was rapidly produced for molecules containing at least one methyl group; red-shifted yellow emission was observed for ones with bulkier side groups other than methyl; and for conformationally locked bicycloamines, no emission was observed. In addition, this fluorochromic process of the naphthalimide derivative not only depends on tertiary amine substituent groups but also shows distinctly different ground- and excited-state photoluminescence dynamics in time-resolved spectroscopy. Based on these differences, a qualitative method is developed for visual recognition of natural and synthetic opioids, including heroin, fentanyl, and metonitazene, which is more facile and rapid compared to current methods such as the Marquis reagent kit, and could facilitate onsite testing, real-time monitoring, and streamlined workflows in both laboratory and field settings.

Cobalt-Catalyzed Asymmetric Hydrogenation of α-Hydroxy Ketones Enabled by a Carboxylic Acid Additive Promotion Strategy

Highly enantioselective hydrogenation of α-hydroxy ketones was achieved by applying the catalytic combination of cobalt acetate and chiral Ph-BPE ligand, supplemented by a carboxylic acid additive promotion strategy. The carboxylic acid additive significantly increases both reactivity and enantioselectivity, allowing for the highly efficient generation of chiral 1,2-diols with up to 99% ee. The application utility is proved through derivations and a total synthesis of (R)-(-)-eliprodil. Mechanistic studies, including control experiments and DFT calculations, support the proposed catalytic mechanism and explain the origin of enantioselectivity.

Unveiling Coverage-Dependent Interactions of N-Methylaniline with the Pt(111) Surface

This study aims to elucidate the adsorption and surface chemistry of N-methylaniline (NMA) on Pt(111), using it as a model molecule to probe the activation mechanisms of aromatic amines on catalytic surfaces. Through a combination of density functional theory (DFT) calculations and experimental techniques such as temperature-programmed X-ray photoelectron spectroscopy (TP-XPS), temperature-programmed desorption (TPD), and Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS), we explored the coverage-dependent behavior of NMA on Pt(111) to identify key steps in the activation process. The population of certain reaction paths is driven by a coverage-dependent balance between molecule surface charge transfer and intermolecular interactions, dictating the selective activation of specific bonds. Our findings reveal how coverage influences the orientation and bonding of NMA on the Pt(111) surface. At lower coverages, the molecule binds to the surface through the phenyl ring and activation, facilitating C-N bond cleavage to the ring under HCN formation. In comparison, at higher coverages, the molecule binds only through the nitrogen atom and desorbs intact. These insights into variable bond activation lay the groundwork for understanding the fundamental processes involved in potential heterogeneously catalyzed reactions of aromatic amines, contributing to the development of new catalytic strategies.

Regulating the production distribution in Ni-Cu nanoparticle mediated nitrile hydrogenation

The selective hydrogenation of nitrile compounds represents a pivotal area of research within both industrial and academic catalysis. In this study, we prepared Ni-Cu bimetallic catalysts through a co-deposition-crystallization sequence, aimed at the efficient production of primary and secondary amines. The enhanced selectivity for primary amines is attributed to the downshift of the d-band center of Ni0.1Cu, which weakens the adsorption of key imine intermediates. Consequently, the synthesized Ni-Cu catalysts demonstrated exceptional catalytic performance in the selective hydrogenation of nitrile compounds, including those with reduction-sensitive functional groups such as -Cl and -Br, achieving 100 % conversion efficiency and significant yields ranging from 80 % to 99 %. The reaction conditions were comprehensively optimized, taking into account factors such as temperature, solvent, time, additives, and hydrogen pressure. Furthermore, the catalytic performance of Ni0.1Cu and Ni0.4Cu in the selective hydrogenation of nitriles was sustained over at least five reaction cycles. Temperature-programmed desorption results elucidated the structure-activity relationship, revealing that a strong interaction site prevails in Ni0.4Cu, while a weaker or moderate interaction site in Ni0.1Cu is responsible for the formation of primary amines. Theoretical calculations indicate that the reaction proceeds via an imine mechanism, with benzylideneimine serving as a key intermediate. This work may stimulate further research into the development of bimetallic nano-catalysts for selective nitrile hydrogenation in industrial catalytic processes.

A well-defined phosphine-free metal-ligand cooperative route for N-alkylation of aromatic amines via activation of renewable alcohols catalyzed by NNN pincer cobalt(II) complexes

This study presents the direct N-alkylation of aromatic amines using greener primary alcohols as alkyl donors, catalyzed by base metal-derived Co(II) catalysts via the borrowing hydrogen (BH) method. Two well-defined phosphine-free NNN-type pincer ligands (L1 and L2) were synthesized and utilized to prepare cobalt(II) catalysts C1 and C2. The catalysts were well characterized by UV-vis, IR, HRMS, and single-crystal X-ray diffraction studies. The catalysts C1 and C2 were utilized for the N-alkylation of various aromatic, heteroaromatic as well as aromatic diamines, and a wide substrate scope total of 30 derivatives was explored with isolated yields up to 95%. Two antihistamine drug precursors for tripelennamine and mepyramine were synthesized on a gram scale for the large-scale applicability of the current protocol. Various control experiments were also performed to explore the possible reaction intermediates and reaction pathway. Cobalt(II) intermediates involved in the catalytic cycle were also characterized by the HRMS study.

Unexpected activity of MgO nanoclusters for the reductive-coupling synthesis of organonitrogen chemicals with C = N bonds

Reductive-coupling of nitro compounds and alcohols is a sustainable route for constructing C = N bonds in organonitrogen chemicals, yet challenging due to the inertness of α-Csp3-H bond in alcohols and the vulnerability of C = N bonds towards hydrogenation. Here, we report the surprising catalytic activity of ultrafine alkaline-earth metal oxide MgO nanoclusters (0.9 ± 0.3 nm) that efficiently activate α-Csp3-H bonds, facilitating the transfer hydrogenation and synthesis of value-added chemicals bearing C = N bonds with high to excellent yields (86-99%). Controlled experiments and characterizations showed the crucial role of oxygen vacancies (Ov) and local Mg environment (Mg-O bond) in MgO for substrate adsorption and activation via electronic interactions between substrate's negatively charged oxygen atoms and Ov sites in MgO nanoclusters. Theoretical calculation further confirmed that Ov significantly lowered the energy barrier of the hydrogen atom transfer from α-Csp3-H in ethanol to the nitro group in nitrobenzene (29.3 vs. 52.9 kcal/mol), which is the rate-determining step with the highest energy barrier in reductive-coupling reactions. Our method not only provides an efficient and sustainable pathway for synthesizing organonitrogen chemicals with C = N bonds but also inspires the exploration of main group element catalysts as alternatives to transition metal and noble metal catalysts for organic transformations.

Electrocatalytic Reductive Amination of Aldehydes and Ketones with Aqueous Nitrite

The electrocatalytic utilization of oxidized nitrogen waste for C-N coupling chemistry is an exciting research area with great potential to be adopted as a sustainable method for generation of organonitrogen molecules. The most widely used C-N coupling reaction is reductive amination. In this work, we develop an alternative electrochemical reductive amination reaction that can proceed in neutral aqueous electrolyte with nitrite as the nitrogenous reactant and via an oxime intermediate. We develop a selection criterion for nitrite reduction electrocatalysts suited for oxime electrosynthesis and, in doing so, find Pd to be a highly efficient catalyst for this reaction, reaching an oxime Faradaic efficiency of 82% at -0.21 V vs the reversible hydrogen electrode. The aliphatic or aromatic structure of the carbonyl reactant impacts the efficacy of the catalyst, with aromatic substrates leading to suppressed oxime formation and detrimental reduction of the carbonyl to the alcohol. We developed a Pb/PbO electrocatalyst that selectively performs oxime reduction in the neutral aqueous electrolyte. With acetone as a model substrate, we demonstrate an efficient one-pot, two-step electrochemical reaction for the conversion of acetone to isopropyl amine with 85% yield and 50% global Faradaic efficiency.

Magnetic Hollowed CoFe Alloy@C Prism Catalyst for N-Alkylation of Alcohols and Amines

A novel magnetic hollowed CoFe@C-650 prism catalyst has been successfully prepared and applied in the N-alkylation of alcohols and amines through a hydrogen borrowing strategy. The catalyst demonstrates good to excellent activities in the reaction with a broad substrate scope to afford up to a 99% yield of target products. A preliminary mechanistic study reveals that a high valent Co species in the catalyst may promote the adsorption and conversion of alcohols, while the Fe species assists in hydrogenating the imine intermediates.

Reduction-Interrupted Tandem Reaction for General Synthesis of Functional Amino Acids by a Heterogeneous Cobalt Catalyst

Despite their significant importance in numerous fields, the challenges in direct and diverse synthesis of γ-amino-α-hydroxybutyric acids (AHBAs) pose substantial obstacles to explore their functions. Here, by preparation of a N-doped carbon-supported bifunctional cobalt catalyst (Co-DAPhen/C), it was applied to develop a reductive tandem reaction for general synthesis of AHBA derivatives from cheap and abundant nitroarenes, formaldehyde, and acrylates. This catalytic three-component reaction features broad substrate and functionality tolerance, an easily accessible and reusable catalyst, and high step and atom economy. The active Co sites of the catalyst are involved in the mild reduction processes with formic acid, whereas the N-doped carbon support enriches the HCHO and acrylates by physical adsorption, thus favoring the capture of hydroxylamine and nitrone intermediates via condensation and 1,3-dipolar cycloaddition, respectively. Such a metal-support synergy interrupts the conventional reduction of nitroarenes into anilines and results in a novel tandem reaction route. In this work, the concept merging mild reduction and effective intermediate transformations is anticipated to develop more useful tandem reactions by rational catalyst design.

Thermally Triggered In Situ Template-Escape Strategy for Controlled Construction of Hollow MOFs

Hollow spherical structures can endow metal-organic framework (MOF) materials with new capabilities. However, devising an uncomplicated synthesis method for hollow MOF spheres remains a formidable challenge. Here, the green hydrothermal method is employed to drive the polymer template, inducing a thermal transition (viscous flow state) that facilitates escape and enables the construction of a series of hollow MOF spheres. The hollow MIL-101(Cr) spherical capsules (Void@MIL-101) with high stability and well-defined morphology are synthesized as the first example. After encapsulating Pd nanoparticles, it exhibits an accelerated mass transfer effect and superior catalytic selectivity in synthesizing secondary aromatic amines. Furthermore, the versatility of this in situ template-escape strategy is demonstrated through the successful construction of hollow CPM-243(Cr) and SiO2 spheres. This innovative approach opens new avenues for the development of various hollow materials with enhanced properties.

A Highly Dispersed Heterogeneous Cobalt Catalyst for Efficient Domino Hydroformylation Reductive Amination of Olefins

The hydroaminomethylation of alkenes using CO and H2 proceeds efficiently in the presence of a heterogeneous Co-N/C catalyst with highly dispersed metal centers. Various secondary and tertiary amines can be effectively synthesized from cyclic and linear aliphatic alkenes using this specific material. The active sites of the optimal catalyst result from the synergistic effect of atomically dispersed Co sites with their surrounding N atoms, and the high surface area as well as structural defects of the NC support. The broad applicability (>54 examples), including pharmaceutically relevant molecules, together with the high activity and reusability, underline the general applicability of this catalytic system.

Tandem reductive amination and deuteration over a phosphorus-modified iron center

Deuterated amines are key building blocks for drug synthesis and the identification of metabolites of new pharmaceuticals, which drives the search for general, efficient, and widely applicable methods for the selective synthesis of such compounds. Here, we describe a multifunctional phosphorus-doped carbon-supported Fe catalyst with highly dispersed isolated metal sites that allow for tandem reductive amination-deuteration sequences. The optimal phosphorus-modified Fe-based catalyst shows excellent performance in terms of both reactivity and regioselectivity for a wide range of deuterated anilines, amines, bioactive complexes, and drugs (>50 examples). Experiments on the gram scale and on catalyst recycling show the application potential of this method. Beyond the direct applicability of the developed method, the described approach opens a perspective for the development of multifunctional single-atom catalysts in other value-adding organic syntheses.

Employing Ammonia for the Synthesis of Primary Amines: Recent Achievements over Heterogeneous Catalysts

Primary amines represent highly privileged chemicals for synthesis of polymers, pharmaceuticals, agrochemicals, coatings, etc. Consequently, the development of efficient and green methodologies for the production of primary amines are of great importance in chemical industry. Owing to the advantages of low cost and ease in availability, ammonia is considered as a feasible nitrogen source for synthesis of N-containing compounds. Thus, the efficient transformation of ammonia into primary amines has received much attention. In this review, the commonly applied synthetic routes to produce primary amines from ammonia were summarized, including the reductive amination of carbonyl compounds, the hydrogen transfer amination of alcohols, the hydroamination of olefins and the arylation with ammonia, in which the catalytic performance of the recent heterogeneous catalysts is discussed. Additionally, various strategies to modulate the surface properties of catalysts are outlined in conjunction with the analysis of reaction mechanism. Particularly, the amination of the biomass-derived substrates is highlighted, which could provide competitive advantages in chemical industry and stimulate the development of sustainable catalysis in the future. Ultimately, perspectives into the challenges and opportunities for synthesis of primary amines with ammonia as N-resource are discussed.

L-Histidine-functionalized KIT-6 with embedded palladium nanoparticles as an efficient heterogeneous catalyst for oxidation of sulfide to sulfoxide and amination of aryl halides

Palladium nanoparticles were supported on L-H-functionalized KIT-6 (KIT-6@L-H-Pd) and evaluated using various characterization techniques such as TGA, FT-IR, SEM, XRD, EDS, and BET. KIT-6@L-H-Pd showed excellent catalytic performance as a recyclable nanocatalyst for the oxidation of sulfides to sulfoxides and the amination of aryl halides. This approach offers multiple benefits, including the use of readily available and cost-effective materials, a straightforward procedure, short reaction durations, high yields, and a catalyst that is easy to separate and reuse. Additionally, the catalyst can be recovered and reused multiple times without significant palladium loss or alteration in its activity.

Dehydrogenative Coupling of Alcohols with Hydrazines under Nickel Catalysis

The development of efficient and robust catalytic systems based on earth-abundant transition metals for fundamentally new transformations is crucial for sustainable chemical synthesis. Herein, an effective and selective Ni-catalyzed dehydrogenative coupling of alcohols with hydrazines with the liberation of ammonia gas is reported. Although several methods were documented for the N-alkylation reaction, the present strategy is conceptually novel, and the reaction proceeds through a pathway involving N-N bond cleavage of phenylhydrazine followed by hydrogen autotransfer. This unprecedented method demonstrates a wide substrate scope, allowing for the synthesis of C-N coupled products from arylhydrazines using various types of alcohols, including aryl, fused aryl, heteroaromatic, cyclic, and aliphatic alcohols, both primary and secondary alcohols. The present catalytic approach was expanded to facilitate selective deuterium incorporation reactions by employing deuterated alcohols at the α-methyl position of the resulting N-alkylated products. It is noteworthy that we have broadened the applicability of the current catalytic systems to facilitate the ketazine synthesis of hydrazine monohydrate by employing secondary alcohols. The reaction utilizes an inexpensive, abundant, and renewable alcohol that serves as both an alkylating and (transfer) hydrogenating agent. Kinetic studies reveal that the reaction rate depends on the concentration of arylhydrazine and the nickel catalyst, following fractional order.

From sugars to aliphatic amines: as sweet as it sounds? Production and applications of bio-based aliphatic amines

Aliphatic amines encompass a diverse group of amines that include alkylamines, alkyl polyamines, alkanolamines and aliphatic heterocyclic amines. Their structural diversity and distinctive characteristics position them as indispensable components across multiple industrial domains, ranging from chemistry and technology to agriculture and medicine. Currently, the industrial production of aliphatic amines is facing pressing sustainability, health and safety issues which all arise due to the strong dependency on fossil feedstock. Interestingly, these issues can be fundamentally resolved by shifting toward biomass as the feedstock. In this regard, cellulose and hemicellulose, the carbohydrate fraction of lignocellulose, emerge as promising feedstock for the production of aliphatic amines as they are available in abundance, safe to use and their aliphatic backbone is susceptible to chemical transformations. Consequently, the academic interest in bio-based aliphatic amines via the catalytic reductive amination of (hemi)cellulose-derived substrates has systematically increased over the past years. From an industrial perspective, however, the production of bio-based aliphatic amines will only be the middle part of a larger, ideally circular, value chain. This value chain additionally includes, as the first part, the refinery of the biomass feedstock to suitable substrates and, as the final part, the implementation of these aliphatic amines in various applications. Each part of the bio-based aliphatic amine value chain will be covered in this Review. Applying a holistic perspective enables one to acknowledge the requirements and limitations of each part and to efficiently spot and potentially bridge knowledge gaps between the different parts.

Metallic Impurities in Electrolysis: Catalytic Effect of Pb Traces in Reductive Amination and Acetone Reduction

The electrochemical hydrogenation (e-hydrogenation) of unsaturated compounds like imines or carbonyls presents a benign reduction method. It enables direct use of electrons as reducing agent, water as proton source, while bypassing the need for elevated temperatures or pressures. In this contribution, we discuss the active species in electrocatalytic reductive amination with the transformation of acetone and methylamine as model reaction. Surprisingly, lead impurities in the ppm-range proved to possess a significant effect in e-hydrogenation. Accordingly, the influence of applied potential and cathode material in presence of 1 ppm Pb was investigated. Finally, we transferred the insights to the reduction of acetone manifesting comparable observations as for imine reduction. The results suggest that previous studies on electrochemical reduction in the presence of lead electrodes should be re-evaluated.

Sustainable ammonia and amines from chitin

Efforts are underway to explore alternative methods to the Haber-Bosch process for sustainable ammonia production, while the potential for ammonia extraction from natural nitrogenous biomass is under-exploited. Here, a synergistic catalytic strategy involving acid and modified Ru-based catalysts is communicated for the direct production of amines and ammonia from chitin. Phosphoric acid promotes the cleavage of ether bonds in biomass polymers and also serves to protect amino groups from being removed. Selective hydrogenation, deoxygenation, and amination can be achieved by controllably adjusting the ratio of Ru0/Run+. The utilization of nitrogen atoms in chitin can reach up to 95 % (21 % amines, 74 % ammonium), and the catalytic process is applicable to waste shrimp shells. This study demonstrates the possibility of efficient production of nitrogen-containing compounds from abundant biopolymers.

Biomass-Derived, Target Specific, and Ecologically Safer Insecticide Active Ingredients

With the continuous increase in food production to support the growing population, ensuring agricultural sustainability using crop-protecting agents, such as pesticides, is vital. Conventional pesticides pose significant environmental risks, prompting the need for eco-friendly alternatives. This study reports the synthesis of new amide-based insecticidal active ingredients from biomass-derived monomers, specifically furfural and vanillin. The process involves reductive amination followed by carbonylation. The synthesis of the furfural-based carbamate yield reaches a cumulative 88 %, with catalysts Rh/Al2O3 and La(OTf)3 being recyclable at each stage. Insecticidal activity assessments reveal that the furfural carbamate exhibits competitive performance, achieving an LC50 of 254.22 μg/cm2, compared to 251.25 μg/cm2 for carbofuran. Ecotoxicity predictions indicate significantly lower toxicity levels toward non-target aquatic and terrestrial species. The importance of the low octanol-water partition coefficient of the biobased carbamate, attributed to the oxygen heteroatom and electron density of the furan ring, is discussed in detail. Building on these promising results, the synthesis strategy was extended to six other biobased aldehydes, resulting in a diverse portfolio of biomass-derived carbamates. A techno-economic analysis reveals a minimum selling price of 11.1 $/kg, only half that of comparable carbamates, demonstrating the economic viability of these new biobased insecticides.

Multifunctionalization of Alkenyl Alcohols via a Sequential Relay Process

Aryl-substituted aliphatic amines are widely recognized as immensely valuable molecules. Consequently, the development of practical strategies for the construction of these molecules becomes increasingly urgent and critical. Here, we have successfully achieved multifunctionalization reactions of alkenyl alcohols in a sequential relay process, which enables transformation patterns of arylamination, deuterated arylamination, and methylenated arylamination to the easy access of multifarious arylalkylamines. Notably, a novel functionalization mode for carbonyl groups has been developed to facilitate the processes of deuterium incorporation and methylene introduction, thereby providing new means for the diverse transformations of carbonyl groups. This methodology displays a wide tolerance toward functional groups, while also exhibiting good applicability across various skeletal structures of alkenols and amines.

One-pot transfer hydrogenation and reductive amination of polyenals

The efficient preparation of long-chain amines via a one-step transfer-hydrogenation/reductive-amination reaction (THRA) of polyenals has been achieved. This strategy, which combines transfer hydrogenation and reductive amination, significantly enhances the synthetic efficiency of amino compounds. Additionally, this protocol offers a practical method for carbon-chain elongation/amination to construct long-chain amino compounds. The reaction system exhibits remarkable versatility in substrate scope using a non-noble ruthenium catalyst with formate and isopropanol as hydrogen sources, making it an appealing method for drug synthesis and molecular modification.

Practical electrochemical hydrogenation of nitriles at the nickel foam cathode

We report a scalable hydrogenation method for nitriles based on cost-effective materials in a very simple two-electrode setup under galvanostatic conditions. All components are commercially and readily available. The method is very easy to conduct and applicable to a variety of nitrile substrates, leading exclusively to primary amine products in yields of up to 89% using an easy work-up protocol. Importantly, this method is readily transferable from the milligram scale in batch-type screening cells to the multi-gram scale in a flow-type electrolyser. The transfer to flow electrolysis enabled us to achieve a notable 20 g day-1 productivity of phenylethylamine at a geometric current density of 50 mA cm-2 in a flow-type electrolyser with 48 cm2 electrodes. It is noteworthy that this method is sustainable in terms of process safety and reusability of components.

Iron-Catalyzed Primary Amination of C(sp3)-H Bonds

Primary amines are privileged molecules in drug development. Yet, there is a noticeable scarcity of methods for directly introducing a primary amine group into the ubiquitous C(sp3)-H bonds within organic compounds. Here, we report an iron-based catalytic system that enables direct primary amination of C(sp3)-H bonds under aqueous conditions and air. Various types of C(sp3)-H bonds, including benzylic, allylic, and aliphatic ones, can be readily functionalized with high selectivity and efficiency. The broad utility of this method has been further verified by late-stage amination of 11 complex bioactive molecules. Mechanistic studies unveil a protonated iron-nitrene complex as the key intermediate for the C-H bond activation. This work extends the toolbox for direct C(sp3)-H functionalizations, opening up new opportunities for late-stage modifications of organic molecules.

Reversal Effect of Phosphorus on Catalytic Performances of Supported Nickel Catalysts in Reductive Amination of 1,6-Hexanediol

The reductive amination of 1,6-hexanediol with ammonia is one of the most promising green routes for synthesis of 1,6-hexanediamine. Herein, we developed a phosphorous modified Ni catalyst of Ni-P/Al2O3. It presented satisfactory improved selectivity to 1,6-hexanediamine in the reductive amination of 1,6-hexanediol compared to the Ni/Al2O3 catalyst. The phosphorous tended to interact with Al2O3 to form AlPOx species, induced Ni nanoparticle to be flatter, and the decrease of strong acid sites, the new-formed Ni-AlPOx-Al2O3 interface and the flatter Ni nanoparticle were the key to switch the dominating product from hexamethyleneimine to 1,6-hexanediamine. This work develops an efficient catalyst for production of 1,6-hexanediamine from the reductive amination of 1,6-hexanediol, and provides a point of view about designing selective non-noble metal catalysts for producing primary diamines via reductive amination of diols.

Development of Iron-Based Single Atom Materials for General and Efficient Synthesis of Amines

Earth abundant metal-based heterogeneous catalysts with highly active and at the same time stable isolated metal sites constitute a key factor for the advancement of sustainable and cost-effective chemical synthesis. In particular, the development of more practical, and durable iron-based materials is of central interest for organic synthesis, especially for the preparation of chemical products related to life science applications. Here, we report the preparation of Fe-single atom catalysts (Fe-SACs) entrapped in N-doped mesoporous carbon support with unprecedented potential in the preparation of different kinds of amines, which represent privileged class of organic compounds and find increasing application in daily life. The optimal Fe-SACs allow for the reductive amination of a broad range of aldehydes and ketones with ammonia and amines to produce diverse primary, secondary, and tertiary amines including N-methylated products as well as drugs, agrochemicals, and other biomolecules (amino acid esters and amides) utilizing green hydrogen.

New insights into butyrylcholinesterase: Pharmaceutical applications, selective inhibitors and multitarget-directed ligands

Butyrylcholinesterase (BChE), also known as pseudocholinesterase and serum cholinesterase, is an isoenzyme of acetylcholinesterase (AChE). It mediates the degradation of acetylcholine, especially under pathological conditions. Proverbial pharmacological applications of BChE, its mutants and modulators consist of combating Alzheimer's disease (AD), influencing multiple sclerosis (MS), addressing cocaine addiction, detoxifying organophosphorus poisoning and reflecting the progression or prognosis of some diseases. Of interest, recent reports have shed light on the relationship between BChE and lipid metabolism. It has also been proved that BChE is going to increase abnormally as a compensator for AChE in the middle and late stages of AD, and BChE inhibitors can alleviate cognitive disorders and positively influence some pathological features in AD model animals, foreboding favorable prospects and potential applications. Herein, the selective BChE inhibitors and BChE-related multitarget-directed ligands published in the last three years were briefly summarized, along with the currently known pharmacological applications of BChE, aiming to grasp the latest research directions. Thereinto, some emerging strategies for designing BChE inhibitors are intriguing, and the modulators based on target combination of histone deacetylase and BChE against AD is unprecedented. Furthermore, the involvement of BChE in the hydrolysis of ghrelin, the inhibition of low-density lipoprotein (LDL) uptake, and the down-regulation of LDL receptor (LDLR) expression suggests its potential to influence lipid metabolism disorders. This compelling prospect likely stimulates further exploration in this promising research direction.

Direct synthesis of chiral β-arylamines via additive-free asymmetric reductive amination enabled by tunable bulky phosphoramidite ligands

This report describes an additive-free iridium-catalyzed direct asymmetric reductive amination that enables the efficient synthesis of chiral β-arylamines, which are important pharmacophores present in a wide variety of pharmaceutical drugs. The reaction makes use of bulky and tunable phosphoramidite ligands for high levels of enantiomeric control, even for alkylamino coupling partners which lack secondary coordinating sites. The synthetic value of this succinct procedure is demonstrated by single-step synthesis of multiple drugs, analogs and key intermediates. Mechanistic investigations reveal an enamine-reduction pathway, in which H-bonding, steric repulsion, and CH-π and electrostatic interactions play important roles in defining the spatial environment for the "outer-sphere" hydride addition.

Reductive Amination of Aldehyde and Ketone with Ammonia and H2 by an In Situ-Generated Cobalt Catalyst under Mild Conditions

Herein, we present the simplest approach for the synthesis of primary amines via reductive amination using H2 as a reductant and aqueous ammonia as a nitrogen source, catalyzed by amorphous Co particles. The highly active Co particles were prepared in situ by simply mixing commercially available CoCl2 and NaBH4/NaHBEt3 without any ligand or support. This reaction system features mild conditions (80 °C, 1-10 bar), high selectivity (99%), a wide substrate scope, simple operation, and easy separation of the catalyst. The successful large-scale application of this reaction in the production of primary amines suggests its potential industrial interest.

High-Throughput Screening and Prediction of Nucleophilicity of Amines Using Machine Learning and DFT Calculations

Nucleophilic index (NNu) as a significant parameter plays a crucial role in screening of amine catalysts. Indeed, the quantity and variety of amines are extensive. However, only limited amines exhibit an NNu value exceeding 4.0 eV, rendering them potential nucleophiles in chemical reactions. To address this issue, we proposed a computational method to quickly identify amines with high NNu values by using Machine Learning (ML) and high-throughput Density Functional Theory (DFT) calculations. Our approach commenced by training ML models and the exploration of Molecular Fingerprint methods as well as the development of quantitative structure-activity relationship (QSAR) models for the well-known amines based on NNu values derived from DFT calculations. Utilizing explainable Shapley Additive Explanation plots, we were able to determine the five critical substructures that significantly impact the NNu values of amine. The aforementioned conclusion can be applied to produce and cultivate 4920 novel hypothetical amines with high NNu values. The QSAR models were employed to predict the NNu values of 259 well-known and 4920 hypothetical amines, resulting in the identification of five novel hypothetical amines with exceptional NNu values (>4.55 eV). The enhanced NNu values of these novel amines were validated by DFT calculations. One novel hypothetical amine, H1, exhibits an unprecedentedly high NNu value of 5.36 eV, surpassing the maximum value (5.35 eV) observed in well-established amines. Our research strategy efficiently accelerates the discovery of the high nucleophilicity of amines using ML predictions, as well as the DFT calculations.

N-Halogenation by Vanadium-Dependent Haloperoxidases Enables 1,2,4-Oxadiazole Synthesis

Nitrogen-containing compounds are valuable synthetic intermediates and targets in nearly every chemical industry. While methods for nitrogen-carbon and nitrogen-heteroatom bond formation have primarily relied on nucleophilic nitrogen atom reactivity, molecules containing nitrogen-halogen bonds allow for electrophilic or radical reactivity modes at the nitrogen center. Despite the growing synthetic utility of nitrogen-halogen bond-containing compounds, selective catalytic strategies for their synthesis are largely underexplored. We recently discovered that the vanadium-dependent haloperoxidase (VHPO) class of enzymes are a suitable biocatalyst platform for nitrogen-halogen bond formation. Herein, we show that VHPOs perform selective halogenation of a range of substituted benzamidine hydrochlorides to produce the corresponding N'-halobenzimidamides. This biocatalytic platform is applied to the synthesis of 1,2,4-oxadiazoles from the corresponding N-acylbenzamidines in high yield and with excellent chemoselectivity. Finally, the synthetic applicability of this biotechnology is demonstrated in an extension to nitrogen-nitrogen bond formation and the chemoenzymatic synthesis of the Duchenne muscular dystrophy drug, ataluren.

Tandem Protocol for Diversified Deuteration of Secondary Aliphatic Amines under Mild Conditions

Deuteration of amine compounds has been widely of concern because of its practical role in organic reaction mechanisms and drug research; however, only limited deuteration label methods are accessible with D2O as a deuterium source. Herein, we propose a convenient deuteration protocol, including preparing D2 by the AlGa activation method, using PtRu nanowires as catalysts, and utilizing the elementary step in the couple reaction involving an imine unit, to realize the rapid preparation of a secondary amine with a diversified deuteration label. The self-coupling between nitriles not only provides a symmetric secondary amine with four α-D atoms but also produces high-valued ND3 in an atomic-economic way.

Asymmetric total syntheses of sarglamides A, C, D, E, and F

Sarglamides A-E were identified as a structurally new class of alkaloids with potential application for inflammation-associated diseases. Reported is the first asymmetric total synthesis of sarglamides A, C, D, E, and F within 7 steps, featuring an intermolecular Diels-Alder cycloaddition of (S)-phellandrene and 1,4-benzoquinone and intramolecular (aza-)Michael addition to construct the tetracyclic core of sarglamides. Importantly, our work demonstrated that the hypothetic Diels-Alder reaction of α-phellandrene with dienophile toussaintine C (or analogues) originally proposed as a biosynthetic pathway was not viable under non-enzymatic conditions. Additionally, we discovered novel and efficient double cyclization (cycloetherification and oxa-Michael cyclization) to construct the core framework of sarglamides E and D. Our concise synthetic strategy might allow rapid access to a library of sarglamide analogues for further evaluation of their bioactivity and mode of action.

Structural Ni0-Niδ+ Pair Sites for Highly Active Hydrogenation of Nitriles to Primary Amines

Supported metal pair sites have sparked interest due to their tremendous potential as bifunctional catalysts. Here, we report the structural Ni0-Niδ+ pair sites constructed in a well-defined nanocrystal phase of Ni3P. These Ni0-Niδ+ pair sites exhibited a remarkable product formation rate of 123 molBA/molmetal/h for the hydrogenation of benzonitrile (BN) to benzylamine (BA). The heterogeneity of surface Ni atoms over the Ni3P crystal created two types of metal centers, Ni0 and Niδ+, with a specific spatial distance of 4-5 Å. The Ni0 site acted as the center for H2 activation, while the Niδ+ site served as the adsorption and activation center for the C ≡ N group. The highly efficient cooperation effect of Ni0-Niδ+ pair sites resulted in a TOF of 2915 h-1 in BN hydrogenation, which is 2.4 and 9.7 times higher than that over the mono-Ni0 and -Niδ+ sites, respectively.

Air-Stable Arene Manganese Complexes as Catalysts for the Syngas-Assisted Direct Reductive Amination, Cyanation of Aldehyde, and CO2 Fixation by Epoxide with High Functional Groups Tolerance

Manganese complexes [(arene)Mn(CO)3]+ were prepared in one step from arenes and Mn(CO)5Br. They were found to be efficient catalysts in the carbonyl cyanation with TMSCN, CO2 fixation by epoxides, and direct reductive amination in the presence of syngas. The amination reaction tolerated various reducible functional groups. The synergy of carbon monoxide and hydrogen in syngas provides high efficiency of the catalytic system. The developed protocols do not require an inert atmosphere, and the catalysts can be handled in air.

Selective nitrogen insertion into aryl alkanes

Molecular structure-editing through nitrogen insertion offers more efficient and ingenious pathways for the synthesis of nitrogen-containing compounds, which could benefit the development of synthetic chemistry, pharmaceutical research, and materials science. Substituted amines, especially nitrogen-containing alkyl heterocyclic compounds, are widely found in nature products and drugs. Generally, accessing these compounds requires multiple steps, which could result in low efficiency. In this work, a molecular editing strategy is used to realize the synthesis of nitrogen-containing compounds using aryl alkanes as starting materials. Using derivatives of O-tosylhydroxylamine as the nitrogen source, this method enables precise nitrogen insertion into the Csp2-Csp3 bond of aryl alkanes. Notably, further synthetic applications demonstrate that this method could be used to prepare bioactive molecules with good efficiency and modify the molecular skeleton of drugs. Furthermore, a plausible reaction mechanism involving the transformation of carbocation and imine intermediates has been proposed based on the results of control experiments.

Photoredox/Bismuth Relay Catalysis Enabling Reductive Alkylation of Nitroarenes with Aldehydes

The effective transition metal-free photoredox/bismuth dual catalytic reductive dialkylation of nitroarenes with benzaldehydes has been reported. The nitroarene reduction through visible light-driven photoredox catalysis was integrated with subsequent reductive dialkylation of anilines under bismuth catalysis to enable the cascade reductive alkylation of nitroarenes with carbonyls. Salient features of this relay catalysis system include mild reaction conditions, no requirement for transition metal catalysts, easy handling, step-economy, and high selectivity.

Chiral bisphosphine Ph-BPE ligand: a rising star in asymmetric synthesis

Chiral 1,2-bis(2,5-diphenylphospholano)ethane (Ph-BPE) is a class of optimal organic bisphosphine ligands with C2-symmetry. Ph-BPE with its excellent catalytic performance in asymmetric synthesis has attracted much attention of chemists with increasing popularity and is growing into one of the most commonly used organophosphorus ligands, especially in asymmetric catalysis. Over two hundred examples have been reported since 2012. This review presents how Ph-BPE is utilized in asymmetric synthesis and how powerful it is as a chiral ligand or even a catalyst in a wide range of reactions including applications in the total synthesis of bioactive molecules.

Integrating Au Catalysis and Engineered Amine Dehydrogenase for the Chemoenzymatic Synthesis of Chiral Aliphatic Amines

Direct synthesis of aliphatic amines from alkynes is highly desirable due to its atom economy and high stereoselectivity but still challenging, especially for the long-chain members. Here, a combination of Au-catalyzed alkyne hydration and amine dehydrogenase-catalyzed (AmDH) reductive amination was constructed, enabling sequential conversion of alkynes into chiral amines in aqueous solutions, particularly for the synthesis of long-chain aliphatic amines on a large scale. The production of chiral aliphatic amines with more than 6 carbons reached 36-60 g/L. A suitable biocatalyst [PtAmDH (A113G/T134G/V294A)], obtained by data mining and active site engineering, enabled the transformation of previously inactive long-chain ketones at high concentrations. Computational analysis revealed that the broader substrate scope and tolerance with the high substrate concentrations resulted from the additive effects of mutations introduced to the three gatekeeper residues 113, 134, and 294.

Ruthenium Complexes with NNN-Pincer Ligands for N-Methylation of Amines Using Methanol

A series of ruthenium complexes (Ru1-Ru4) bearing new NNN-pincer ligands were synthesized in 58-78% yields. All of the complexes are air and moisture stable and were characterized by IR, NMR, and high-resolution mass spectra (HRMS). In addition, the structures of Ru1-Ru3 were confirmed by X-ray crystallographic analysis. These Ru(II) complexes exhibited high catalytic efficiency and broad functional group tolerance in the N-methylation reaction of amines using CH3OH as both the C1 source and solvent. Experimental results indicated that the electronic effect of the substituents on the ligands considerably affects the catalytic reactivity of the complexes in which Ru3 bearing an electron-donating OMe group showed the highest activity. Deuterium labeling and control experiments suggested that the dehydrogenation of methanol to generate ruthenium hydride species was the rate-determining step in the reaction. Furthermore, this protocol also provided a ready approach to versatile trideuterated N-methylamines under mild conditions using CD3OD as a deuterated methylating agent.

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 acetonitrile solvent; while taking methanol as solvent, the C=N bonds are readily hydrogenated to the C-N bonds via hydrogen-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 solvents in photocatalytic organic transformations.

Carbon-Supported Ru-Ni and Ru-W Catalysts for the Transformation of Hydroxyacetone and Saccharides into Glycol-Derived Primary Amines

Nitrogen-containing molecules are used for the synthesis of polymers, surfactants, agrochemicals, and dyes. In the context of green chemistry, it is important to form such compounds from bioresource. Short-chain primary amines are of interest for the polymer industry, like 2-aminopropanol, 1-aminopropan-2-ol, and 1,2-diaminopropane. These amines can be formed through the amination of oxygenated substrates, preferably in aqueous phase. This is possible with heterogeneous catalysts, however, effective systems that allow reactions under mild conditions are lacking. We report an efficient catalyst Ru-Ni/AC for the reductive amination of hydroxyacetone into 2-aminopropanol. The catalyst has been reused during 3 cycles demonstrating a good stability. As a prospective study, extension to the reactivity of (poly)carbohydrates has been realized. Despite a lesser efficiency, 2-aminopropanol (9 % yield of amines) has been formed from fructose, the first example from a carbohydrate. This was possible using a 7.5 %Ru-36 %WxC/AC catalyst, composition allowing a one-pot retro-aldol cleavage into hydroxyacetone and reductive amination. The transformation of cellulose through sequential reactions with a combination of 30 %W2C/AC and 7.5 %Ru-36 %WxC/AC system gave 2 % of 2-aminopropanol, corresponding to the first example of the formation of this amine from cellulose with heterogeneous catalysts.

In-silico-assisted derivatization of triarylboranes for the catalytic reductive functionalization of aniline-derived amino acids and peptides with H2

Cheminformatics-based machine learning (ML) has been employed to determine optimal reaction conditions, including catalyst structures, in the field of synthetic chemistry. However, such ML-focused strategies have remained largely unexplored in the context of catalytic molecular transformations using Lewis-acidic main-group elements, probably due to the absence of a candidate library and effective guidelines (parameters) for the prediction of the activity of main-group elements. Here, the construction of a triarylborane library and its application to an ML-assisted approach for the catalytic reductive alkylation of aniline-derived amino acids and C-terminal-protected peptides with aldehydes and H2 is reported. A combined theoretical and experimental approach identified the optimal borane, i.e., B(2,3,5,6-Cl4-C6H)(2,6-F2-3,5-(CF3)2-C6H)2, which exhibits remarkable functional-group compatibility toward aniline derivatives in the presence of 4-methyltetrahydropyran. The present catalytic system generates H2O as the sole byproduct.

Multicomponent Reductive Coupling for Selective Access to Functional γ-Lactams by a Single-Atom Cobalt Catalyst

Despite their significant importance to numerous fields, the difficulties in direct and diverse synthesis of α-hydroxy-γ-lactams pose substantial obstacles to their practical applications. Here, we designed a nitrogen and TiO2 co-doped graphitic carbon-supported material with atomically dispersed cobalt sites (CoSA-N/NC-TiO2), which was successfully applied as a multifunctional catalyst to establish a general method for direct construction of α-hydroxy-γ-lactams from cheap and abundant nitro(hetero)arenes, aldehydes, and H2O with alkynoates. The striking features of operational simplicity, broad substrate and functionality compatibility (>100 examples), high step and atom efficiency, good selectivity, and exceptional catalyst reusability highlight the practicality of this new catalytic transformation. Mechanistic studies reveal that the active CoN4 species and the dopants exhibit a synergistic effect on the formation of key acid-masked nitrones; their subsequent nucleophilic addition to the alkynoates followed by successive reduction, alkenyl hydration, and intramolecular ester ammonolysis delivers the desired products. In this work, the concept of reduction interruption leading to new reaction route will open a door to further develop useful transformations by rational catalyst design.