A very simple and highly efficient procedure for N-formylation of primary and secondary amines at room temperature under solvent-free conditions

Synthesis and structural analysis of a ZIF-9/GO composite for green catalytic C-C bond formation and N-formylation: a spectroscopic study

We report a new synthetic approach for a ZIF-9/GO composite material at room temperature and its comprehensive characterization using a variety of techniques, including PXRD, FT-IR, Raman, UV-vis, DRS, TGA, SEM, FE-SEM, EDX, TEM, ICP-MS, XPS, and BET. The material exhibited a moderate surface area and good thermal stability, as indicated by BET and TGA results. DRS revealed a band gap of 3.4 eV, which indicates slight semiconductor nature of the material. The crystalline nature of the ZIF-9/GO composite was confirmed by PXRD. The ZIF-9/GO composite exhibited excellent catalytic efficiency as a heterogeneous catalyst in Knoevenagel condensation and N-formylation, achieving yields of up to 98% under green reaction conditions with a wide range of substrate tolerance. The E-factor (0.10) and atom economy (91.7%) values were very close to ideal green chemistry parameters. In situ and UV-vis studies revealed reaction intermediates. The practical utility of this protocol was demonstrated by the gram scale synthesis of the value-added compounds 2-imino-2H-1-benzopyran-3-carbonitrile and paracetamol. Single-crystal XRD analysis of three of the compounds confirmed their structural integrity. The catalyst was easily separated via filtration and reused for up to six catalytic cycles without significant loss of activity, which is a crucial component of green synthesis, and hot-filtration experiments confirmed its heterogeneity. The probable mechanisms for both reactions are also well presented.

Photoinduced Direct Formylation of Anilines: Aerobic Oxidation Using an Odd Alternate Hydrocarbon Phenalenyl-Based Photocatalyst

We have introduced a sustainable approach for the photoinduced oxidative formylation of N,N-dimethylanilines using a phenalenyl-based photocatalyst. The methodology exhibits tolerance to a variety of electron-donating and -withdrawing groups as well as to diverse functional groups, specifically offering a selective and efficient pathway for the N-formylation. Using visible light, this photochemical technique proves to be an environmentally friendly, scalable, and milder alternative strategy. The mechanistic insights were gained through a series of spectroscopic techniques, including electron paramagnetic resonance, steady-state fluorescence, and fluorescence lifetime studies. Postfunctionalization was also completed and has the potential to be used in various applications.

DNA-Compatible N-Formylation of Amines by Using TMSCF2Br

DNA-encoded libraries (DELs) have emerged as powerful tools in drug discovery. Protected amino acids serve as essential building blocks in the construction of DELs, resulting in the widespread presence of amino groups within these libraries. N-formylation of free amines not only enhances the activity of lead compounds but also functions as an effective amino-protecting strategy. In this study, we introduce trimethyl(bromodifluoromethyl)silane (TMSCF2Br) as a novel N-formylation reagent for DEL synthesis. This approach demonstrates robustness in DEL-compatible synthesis and enables library diversification through functional group transformation (FGT). Additionally, we achieved efficient removal of formyl groups, enabling the formyl group to be strategically used for on-DNA amino protection orthogonal to Fmoc and Boc groups.

Mechanistic Insights into the Methylation and Formylation of Amines with CO2: Exploring Diverse CO2 Activation Models

The urgent need to address global warming and resource depletion has spurred research into sustainable methods for the utilization of CO2 as a C1 source. However, the challenge remains in developing metal-free, cost-effective, and environmentally friendly approaches for CO2 conversion. Here, we investigate the mechanisms of CO2 activation in the methylation and formylation of amines using both theoretical and experimental approaches. Our study reveals that the methylation process is complex, with the "double H model" proving most effective, while the formylation reaction is more straightforward, favoring the "single H model." Control experiments confirmed these distinct activation models by monitoring the HCOOH formation. We further evaluated key influencing factors, including Hirshfeld charge and nucleophilicity. Based on our findings, we successfully designed new reactions, demonstrating the practical applications of these mechanisms. This research provides valuable insights into CO2 conversion strategies, advancing the field of sustainable chemistry.

Palladium-Catalyzed One-Pot Synthesis of N-Formylaniline Derivatives Using Oxalic Acid as a Dual Carbon Monoxide and Hydrogen Donor

A palladium-catalyzed three-component reaction enabled the synthesis of N-formylanilines from aryl iodides, NaN3, and oxalic acid. This one-pot process involves aminocarbonylation, the Curtius rearrangement, and reduction using oxalic acid as both a carbon monoxide and hydrogen donor. The method has a broad substrate scope, tolerates various functional groups, and delivers N-formylanilines in high yields, making it a green and useful synthetic approach.

A potential DES catalyst for the fast and green synthesis of benzochromenopyrimidines and pyranopyrimidines

A gentisic acid based-Deep Eutectic Solvent (MTPPBr/GA-DES) was synthesized by mixing one mole of methyl triphenylphosphonium bromide (MTPPBr) and one mole of gentisic acid (GA: 2,5-dihydroxy-benzoic acid) based on the eutectic point phase diagram. Then, it was characterized by FT-IR, NMR, densitometer, and TGA/DTA techniques and used as a potent and novel catalyst for the fast and green synthesis of: (i) Five new 2(a-e) and five known 2(f-j) benzo[6,7]chromeno[2,3-d]pyrimidines and (ii) One new (3a) and eleven known 3(b-l) pyrano[2,3-d]pyrimidines, in solvent-free conditions, short reaction times, and high yields. It is important to mention that for the synthesis of 2(a-j), there is only one reference which states that the reaction times are extremely long (720-2400 min), while these times are reduced to approximately 35-50 min in our proposed strategy, indicatinging that the rate of reactions will be 20-48 times faster, which is the clear and most obvious advantage of our approach.

La-Catalyzed Decarbonylation of Formamides and Its Applications

Herein we report the first catalytic decarbonylation and decarbonylative hydroamination of formamides without using additives enabled by a redox-neutral rare earth catalyst. The protocol displays complete N-aryl/alkenyl formamide-selectivity, thus providing a wide variety of creative uses of the N-formylation and N-deformylation method and opening up new prospects for minimizing waste and controlling the required selectivity in amine transformation events.

Chemical preparation, degradation analysis, computational docking and biological activities of novel sulfonylureas with 2,5-disubstituted groups

Based on the previous finding that a substitution at 5-position of the benzene ring is favorable to enhance the degradation rates of sulfonylurea herbicides, a total of 16 novel 2,5-disubsituted sulfonylurea compounds were chemically synthesized and fully characterized by means of ¹H NMR, ¹³C NMR, HRMS and X-ray diffraction. By using HPLC analysis, the degradation behavior of M03, a compound belonging to this family, was studied and confirmed that chlorsulfuron itself is not a degraded product of the 2,5-disubstituted sulfonylureas. Inhibition constants against plant acetohydroxyacid synthase (AHAS) were determined for selected compounds, among which SU3 showed seven times stronger activity against the mutant W574L enzyme than chlorsulfuron. Molecular docking suggested that the substituted group at 5-position of benzene ring is likely to interact with the surrounding residues Met200 and Asp376 of AtAHAS. From the greenhouse herbicidal assay and crop safety test, SU5 and SU6 are considered as herbicide candidates to control dicotyledon weeds in corn, while SU3 is likely to be a promising candidate to control dicotyledon weed species and barnyard grass in wheat. The present research has therefore provided some new insights to understand the structure-activity relationships of herbicidal sulfonylureas with di-substitutions at benzene ring.

N-Formylsaccharin: A Sweet(able) Formylating Agent in Mechanochemistry

The acylation of amines has always attracted a deep interest as a synthetic route due to its high versatility in organic chemistry and biochemical processes. The purpose of this article is to present a mechanochemical acylation procedure based on the use of acyl-saccharin derivatives, namely N-formylsaccharin, N-acetylsaccharin, and N-propionylsaccharin. This protocol furnishes a valuable solvent-free alternative to the existing processes and aims to be highly beneficial in multi-step procedures due to its rapid and user-friendly workup.

Sustainable catalyst-free N-formylation using CO2 as a carbon source

The development of new sustainable catalytic conversion methods of carbon dioxide (CO2) is of great interest in the synthesis of valuable chemicals. N-formylation of CO2 with amine nucleophiles as substrates has been studied in depth. The key to benign formylation is to select a suitable reducing agent to activate CO2. This paper showcases the activation modes of CO2 and the construction strategies of sustainable and catalyst-free N-formylation systems. The research progress of catalyst-free N-formylation of amines and CO2 is reviewed. There are two broad prominent categories, namely reductive amidation of CO2 facilitated by organic solvents and ionic liquids in the presence of hydrosilane. Attention is also paid to discussing the involved reaction mechanism with practical applications and identifying the remaining challenges in this field.

Facile access to N-formyl imide as an N-formylating agent for the direct synthesis of N-formamides, benzimidazoles and quinazolinones

N-Formamide synthesis using N-formyl imide with primary and secondary amines with catalytic amounts of p-toluenesulfonic acid monohydrate (TsOH·H₂O) is described. This reaction is performed in water without the use of surfactants. Moreover, N-formyl imide is efficiently synthesized using acylamidines with TsOH·H₂O in water. In addition, N-formyl imide was successfully used as a carbonyl source in the synthesis of benzimidazole and quinazolinone derivatives. Notable features of N-formylation of amines by using N-formyl imide include operational simplicity, oxidant- and metal-free conditions, structurally diverse products, and easy applicability to gram-scale operation.

Research on the controllable degradation of N-methylamido and dialkylamino substituted at the 5th position of the benzene ring in chlorsulfuron in acidic soil

Owing to the lengthy residual problems associated with chlorsulfuron, metsulfuron-methyl, and ethametsulfuron, which prevents them from being used in the "annual multi-crop planting system", the application of these sulfonylurea herbicides (SU) has regrettably been terminated in China since 2014. In this field, we were the first to discover that the 5th position of the benzene ring in chlorsulfuron is a key point for influencing its degradation rate and the amino moiety at this position showed faster degradation rates and maintained their original potent bioactivity. In this study, we further elaborated on N-methylamido and dialkylamino substituents at the same position in chlorsulfuron to obtain 18 novel structures as M and N series. Their half-life degradation (DT50) values were faster, to varying degrees, than chlorsulfuron in acidic soil. It was found that most of the titled structures also retained their potent herbicidal activity and the crop safety of the M series towards corn greatly increased. Based on these data, a comprehensive graph describing the structure/degradation relationship was established first. Relating to the new molecules, their herbicidal activity (A), degradation rates (D), and crop safety (S) relationship were correlated and we used this approach to predict and explore the most preferable molecule, which coincided to the corresponding experimental data. The new concept of controllable degradation will provide us with more insight when searching for new ecological bioactive molecules in the future.

MoS2-Catalyzed transamidation reaction

The MoS2-catalyzed transamidation reaction with high yields using N,N-dimethylformamide and other amides as carbonyl sources is developed here. The protocol is simple, does not require any additive such as acid, base, ligand, etc., and encompasses a broad substrate scope for primary, secondary and heterocyclic amines. Moreover, the acetylation and propanylation of amines also can be achieved with good to excellent yield by this strategy.

Visible-Light-Induced Radical Cascade Cyclization: Synthesis of the ABCD Ring Cores of Camptothecins

A new strategy for constructing indolizino[1,2-b]quinolin-9(11H)-ones (ring cores of camptothecins) from readily available isocyanoarenes and N-(alkyl-2-yn-1-yl)pyridin-2(1H)-ones has been developed through a visible-light-induced radical cascade cyclization process. The reaction proceeds under mild conditions with fair to excellent yields. The easy introduction of substituents for both reactants and the broad functional group tolerance of the reaction make it a straightforward route to the cores of the marketed camptothecins and their derivatives.

Formyloxyacetoxyphenylmethane as an N-Formylating Reagent for Amines, Amino Acids, and Peptides

Formyloxyacetoxyphenylmethane is a stable, water-tolerant, N-formylating reagent for primary and secondary amines that can be used under solvent-free conditions at room temperature to prepare a range of N-formamides, N-formylanilines, N-formyl-α-amino acids, N-formylpeptides, and an isocyanide.

Catalyst-Free One-Pot Three-Component Synthesis of Diversely Substituted 5-Aryl-2-oxo-/thioxo-2,3-dihydro-1H-benzo[6,7]chromeno[2,3-d]pyrimidine-4,6,11(5H)-triones Under Ambient Conditions

A simple, catalyst-free, straightforward, and highly efficient one-pot synthesis of pharmaceutically interesting diverse kind of a new series of functionalized 5-aryl-2-oxo-/thioxo-2,3-dihydro-1H-benzo[6,7]chromeno[2,3-d]pyrimidine-4,6,11(5H)-triones 4 (4-1-4-37) and substituted 5,5'-(1,4-phenylene)bis(2-oxo-/thioxo-2,3-dihydro-1H-benzo[6,7]chromeno[2,3-d]pyrimidine-4,6,11(5H)-trione) derivatives 4' (4'-1-4'-3) has been developed based on a three-component reaction between barbituric acid/N,N-dimethylbarbituric acid/2-thiobarbituric acid (1), aromatic aldehydes (2), and 2-hydroxy-1,4-naphthoquinone (3) in aqueous ethanol at room temperature (25-30 °C). The salient features of this protocol are mild reaction conditions, use of no catalyst, no need of column chromatographic purification, excellent yields, high atom economy, eco-friendliness, easy isolation of products, and reusability of reaction media.

Recent developments on ultrasound assisted catalyst-free organic synthesis

Mother Nature needs to be protected from ever increasing chemical pollutions associated with synthetic organic processes. The fundamental challenge for today's methodologists is to make their protocols more environmentally benign and sustainable by avoiding the extensive use of hazardous reagents and solvents, harsh reaction conditions, and toxic metal catalysts. However, the people of the twenty-first century are well aware about the side effects of those hazardous substances used and generated by the chemical processes. As a result, the last decade has seen a tremendous outburst in modifying chemical processes to make them 'sustainable' for the betterment of our environment. Catalysts play a crucial role in organic synthesis and thus they find huge applications and uses. Scientists' continuously trying to modify the catalysts to reduce their toxicity level, but the most benign way is to design an organic reaction without catalyst(s), if possible. It is worthy to mention that the involvement of ultrasound in organic synthesis is sometimes fulfilling this goal. In many occasions the applications of ultrasound can avoid the use of catalysts in organic reactions. Such beneficial features as a whole have motivated the organic chemists to apply ultrasonic irradiation in more heights and as a results, in recent past, there were immense applications of ultrasound in organic reactions for the synthesis of diverse organic scaffolds under catalyst-free condition. The present review summarizes the latest developments on ultrasound assisted catalyst-free organic synthesis reported so far.

Application of polydopamine sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (Fe3O4@PDA-SO3H) as a heterogeneous and recyclable nanocatalyst for the formylation of alcohols and amines under solvent-free conditions

Herein, a highly effective and solvent-free Fe₃O₄@PDA-SO₃H catalyzed technique was advanced for N-formylation of alcohols, phenols and amines with ethyl formate.

An imidazolium based ionic liquid supported on Fe3O4@SiO2 nanoparticles as an efficient heterogeneous catalyst for N-formylation of amines

An ionic liquid supported on silica-coated ferrite nanoparticles as an efficient and reusable catalyst for N-formylation of amines.