Concise and versatile multicomponent synthesis of multisubstituted polyfunctional dihydropyrroles

Iron-Mediated C-H Functionalization of Unactivated Alkynes for the Synthesis of Derivatized Dihydropyrrolones: Regioselectivity Under Thermodynamic Control

Cyclopentadienyliron dicarbonyl-based complexes present opportunities for underexplored disconnections in synthesis. Access to challenging dihydropyrrolone products is achieved by propargylic C-H functionalization of alkynes for the formation of cyclic organoiron species. Excellent regioselectivity for unsymmetrical alkynes is observed in many cases. Notably, regioselectivity under these stoichiometric conditions diverges from those observed previously under catalysis, occurring at the more-substituted terminus of the alkyne, allowing for methine functionalization and the formation of quaternary centers. Divergent demetallation of the intermediate organoiron complexes gives access to chemically diverse products which are amenable to further functionalization.

Synthesis of polyfunctionalized dihydro-2-oxypyrroles catalyzed by 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as a novel donor-acceptor fluorophore

We developed a green radical synthesis method for polyfunctionalized dihydro-2-oxypyrroles based on the Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylates, and formaldehyde. To generate a renewable energy sources from visible light, a PCET (proton-coupled electron transfer) photocatalyst was used in an ethanol solution in an air environment and at room temperature. In this study, we aim to develop an inexpensive and easily accessible novel donor–acceptor (D–A) fluorophore. Besides its speed-saving features and ease of use, the carbazole-based photocatalyst (4CzIPN) also shows high yields, energy-efficient, and is environmentally friendly. In this way, it is possible to monitor changes in chemical and environmental variables over time. The variety of yields is pretty uniform (84–97%, average 92.3%), and the kind of response times be very speedy (15–25 min, average 17.6 min), and the element noted within the dialogue is that the system tolerates a variety of donating and withdrawing functional groups, at the same time as nevertheless giving very fast rate and tremendous yields. A study of polyfunctionalized dihydro-2-oxypyrroles was conducted to calculate the turnover number (TON) and turnover frequency (TOF). Gram-scale cyclization proves that it can be applied to industry in a practical manner.

Acridine yellow G (AYG) as a photo-induced electron transfer (PET) photocatalyst employed for the radical Michael–Mannich cyclocondensation of imines

A four-component domino Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylaes, and formaldehyde was utilized to develop a green technique for sans metal combination of polyfunctionalized dihydro-2-oxypyrroles. It involves visible light as an environmentally friendly power source and acridine yellow G (AYG) as a photo-induced electron transfer (PET) photocatalyst. The motivation behind this examination was to expand the utilization of a non-metal dye that is both reasonable and broadly accessible. Photochemically catalyzed AYG flaunts exceptional returns, energy effectiveness, and natural agreeableness, as well as extraordinary iota economy, efficient highlights, and comfort of purpose. Key abilities consist of an easy experimental setup, big substrate tolerance, finance-friendly, clean painting-up strategies within the absence of tedious separation techniques, and minimized the quantity of waste for each organic transformation. The type of yields is pretty uniform (85–97%, average 92.09%), and the shape of reaction times might be very speedy (15–30 min, average 21.59 min), and the factor stated inside the dialogue is that the method tolerates quite a number electron-donating and electron-withdrawing functional groups, while, however, giving extremely good yields. The response within the reason is insensitive to the person of the substituents. Subsequently, many compounds and natural factors can be followed over the course of time. Shockingly, gram-scale cyclization is conceivable, proposing that the strategy could be utilized in industry.

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

Substituted 4-acetyl-3-hydroxy-3-pyrroline-2-ones have been prepared via three-component reactions and the tautomerism of these 3-pyrroline-2-ones is due to the slight difference of energy, and the significantly large rate constant of transformation between two tautomers. 1,4,5-Trisubstituted pyrrolidine-2,3-dione derivatives were prepared from the above mentioned 2-pyrrolidinone derivatives and aliphatic amines, which exist in enamine form and are stabilized by an intramolecular hydrogen bond. A possible reaction mechanism between 3-pyrroline-2-one and aliphatic amine (CH₃NH₂) was proposed based on computational results and the main product is formed favorably following the PES via the lowest ΔG^# pathway in both the gas-phase and an ethanol solvent model. DFT calculations showed that kinetic selectivity is more significant than thermodynamic selectivity for forming main products.

The development of imin-based tandem Michael-Mannich cyclocondensation through a single-electron transfer (SET)/energy transfer (EnT) pathway in the use of methylene blue (MB+) as a photo-redox catalyst

A four-component green tandem approach for the metal-free synthesis of polyfunctionalized dihydro-2-oxypyrroles was devised using the Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylaes, and formaldehyde. Photo-excited state functions generated from methylene blue (MB⁺) were employed as single-electron transfer (SET) and energy transfer (EnT) catalysts at ambient temperature in an ethanol solvent, employing visible light as a renewable energy source in the air atmosphere. This study aims to increase the usage of a non-metal cationic dye that is both inexpensive and widely available. Methylene blue is photochemically produced with the least amount of a catalyst due to its high yields, energy-effectiveness, high atom economy, time-saving features of the reaction, and operational simplicity. As a result, a variety of ecological and long-term chemical features are achieved. Surprisingly, such cyclization can be done on a gram scale, implying that the process has industrial potential.

A four-component green tandem approach for the metal-free synthesis of polyfunctionalized dihydro-2-oxypyrroles was devised using the Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylaes, and formaldehyde.

Application of highly efficient and reusable H3PW12O40/Fe3O4@SiO2-Pr-Pi nanocatalyst for preparation of dihydro-2-oxypyrrole derivatives

In this study, a novel heterogeneous catalyst (H3PW12O40/Fe3O4@SiO2-Pr-Pi) was prepared via immobilization of H3PW12O40 on the surface of piperidine modified magnetic nanoparticles (Fe3O4@SiO2-Pr-Pi). The synthesis of dihydro-2-oxypyrrole derivatives was carried out by the reaction of substituted aniline, formaldehyde, and dimethyl acetylenedicarboxylate, promoted by H3PW12O40/Fe3O4@SiO2-Pr-Pi in EtOH. The formation of resultant catalyst was confirmed by FTIR spectroscopy, FE-SEM, EDX, VSM, and TGA techniques. The magnetically separable and environmentally friendly nanostructured catalyst remained quite stable during reaction conditions and was reused for at least five recycle runs.

Discovery of dihydropyrrolidones as novel inhibitors against influenza A virus

More effective prophylactic and therapeutic strategies to combat influenza viruses are urgently required worldwide because the conventional anti-influenza drugs are facing drug resistance. Here, dihydropyrrolidones (DHPs), the products of an efficient multi-components reaction, were found to possess good activities against influenza A virus (IAV). Primary structure-activity relationship indicated that the activities of DHPs were greatly influenced by substituents and four of them had IC₅₀ values lower than 10 μM (DHPs 5-2, 8, 14 and 19: IC₅₀ = 3.11-9.23 μM). The activities against multiple IAV strains and mechanism of DHPs were further investigated by using 5-2 (IC₅₀ = 3.11 μM). It was found that 5-2 possessed antiviral effects against all the investigated subtypes of IAVs with the IC₅₀ values from 3.11 to 7.13 μM. Moreover, 5-2 showed very low cytotoxicity with CC₅₀ > 400 μM. Results of mechanism study indicated that 5-2 could efficiently inhibit replication of IAV, up-regulate the expression of key antiviral cytokines IFN-β and antiviral protein MxA, and suppress the production of the NDAPH oxidase NOX1 in MDCK cells. These results indicated that 5-2 could be used as a potential inhibitor against wide subtypes of IAVs.

One-pot synthesis of 4-ethyl 2,3-dimethyl 1-(5-aryl-1,3,4-thiadiazol-2-yl)-5-oxo-2,5-dihydro-1H-pyrrole-2,3,4-tricarboxylate derivatives via intramolecular Wittig reaction

A facile one-pot synthesis of highly functionalized dialkyl 1-(5-aryl-1,3,4-thiadiazol-2-yl)-4-ethoxy-5-oxo-2,5-dihydro-1 H-pyrrole-2,3-dicarboxylate derivatives via the reaction between acetylenic esters, triphenylphosphine, and ethyl 2-[(5-aryl-1,3,4-thiadiazol-2-yl)amino]-2-oxoacetate is developed. The structure of the products is confirmed by spectroscopic methods.

New frontiers in the transition-metal-free synthesis of heterocycles from alkynoates: an overview and current status

This review highlights the successful utilization of transition-metal-free approaches for the modular assembly of various heterocycles from alkynoates.

Multi-component synthesis of piperidines and dihydropyrrol-2-one derivatives catalyzed by a dual-functional ionic liquid

N,N,N’, N’-tetramethyl- N,N’-bis(sulfo)ethane-1,2-diaminium mesylate ([TMBSED][OMs]2) was employed for the synthesis of piperidines and dihydropyrrol-2-ones via one-pot multi-component reactions in simple and green processes. This pseudo five-component reaction of aromatic aldehydes, anilines and alkyl acetoacetates was carried out under reflux conditions in ethanol to afford substituted piperidines. Also, dihydropyrrol-2-one derivatives were synthesized by means of four-component reactions of various amines, dialkyl acetylenedicarboxylates and formaldehyde in ethanol at room temperature. The present approaches have several advantages such as good yields, easy work-ups, short reaction times, and utilize mild and clean reaction conditions.

Synthesis of functionalized dihydro-2-oxopyrroles using graphene oxide as heterogeneous catalyst

A mild, efficient synthetic approach for the synthesis of highly functionalized dihydro-2-oxopyrroles is developed by using graphene oxide, a readily available and inexpensive material, as an eco-benign solid acid catalyst in ethanol at room temperature. The present methodology displays several advantages such as practical simplicity, high atom economy, easy workup procedure, and high yields of the products.

An Efficient Synthesis of Pyrrolidinone Derivatives in the Presence of 1,1′-Butylenebis(3-sulfo-3H-imidazol-1-ium) Chloride

The catalytic efficiency of 1,1′-butylenebis(3-sulfo-3H-imidazol-1-ium) chloride as a sulfonic acid-functionalized ionic liquid was demonstrated for the synthesis of pyrrolidinone derivatives under mild conditions. The electronic effect of substituents on aniline derivatives was investigated. Further, a study on the structure–activity relationship of ionic liquids containing sulfonic groups for the synthesis of ethyl-2-(4-chlorophenyl)-4-hydroxy-5-oxo-1-(p-tolyl)-2,5-dihydro-1H-pyrrole-3-carboxylate was performed under optimal conditions. The results showed that the catalytic properties of ionic liquids containing two sulfonic or imidazole moieties with carbon spacers was superior to ionic liquids having one sulfonic or imidazole moiety with no carbon spacer.

Metal-Free Multicomponent Tandem Polymerizations of Alkynes, Amines, and Formaldehyde toward Structure- and Sequence-Controlled Luminescent Polyheterocycles

Sequence-controlled polymers, including biopolymers such as DNA, RNA, and proteins, have attracted much attention recently because of their sequence-dependent functionalities. The development of an efficient synthetic approach for non-natural sequence-controlled polymers is hence of great importance. Multicomponent polymerizations (MCPs) as a powerful and popular synthetic approach for functional polymers with great structural diversity have been demonstrated to be a promising tool for the synthesis of sequence-controlled polymers. In this work, we developed a facile metal-free one-pot multicomponent tandem polymerization (MCTP) of activated internal alkynes, aromatic diamines, and formaldehyde to successfully synthesize structural-regulated and sequence-controlled polyheterocycles with high molecular weights (up to 69 800 g/mol) in high yields (up to 99%). Through such MCTP, polymers with the in situ generated multisubstituted tetrahydropyrimidines or dihydropyrrolones in the backbone and inherent luminescence can be easily obtained with high atom economy and environmental benefit, which is inaccessible by other synthetic approaches.

Synthesis of highly substituted dihydro-2-oxopyrroles using Fe3O4@nano-cellulose–OPO3H as a novel bio-based magnetic nanocatalyst

A green and environmentally friendly approach for the synthesis of dihydro-2-oxopyrrole derivatives was developed using Fe₃O₄@nano-cellulose–OPO₃H as a novel bio-based magnetic nanocatalyst.

Efficient Synthesis of a Series of Novel Octahydroquinazoline-5-ones via a Simple on-Water Urea-Catalyzed Chemoselective Five-Component Reaction

Multicomponent reactions (MCRs) have become a powerful tool for drug discovery and development owing to their advantages of fast and efficient construction of a large library of products with complexity and diversity. However, conventional MCRs usually proceed in environmentally unfriendly organic solvents rather than in water, a green solvent used by nature for biological chemistry. Herein, a simple and efficient on-water urea-catalyzed chemoselective five-component reaction (5CR) has been developed for the synthesis of a series of novel octahydroquinazoline-5-ones (6), the derivatives of quinazolinones possessing diverse biological activities. The molecular structure of 6{1,1,12} has been confirmed by single-crystal X-ray diffraction. The 5CR can proceed at room temperature under normal atmospheric pressure in good yields and afford a large library of octahydroquinazoline-5-ones with various aromatic and aliphatic substituents at N-1, C-2, and N-3. In addition, a green method has been developed for the synthesis of enaminones, important intermediates in the 5CR and in synthetic chemistry.

Synthesis of functionalized dihydro-2-oxypyrroles and tetrahydropyridines using 2,6-pyridinedicarboxylic acid as an efficient and mild organocatalyst

Simple and mild one-pot protocols for the synthesis of diversely functionalized dihydro-2-oxypyrroles and tetrahydropyridines using catalytic amounts of 2,6-PDCA.

The UiO-66-SO3H metal–organic framework as a green catalyst for the facile synthesis of dihydro-2-oxypyrrole derivatives

The multicomponent domino reaction synthesis of dihydro-2-oxopyrroles has been performed using the sulfonated metal–organic framework, UiO-66-SO₃H (UiO is the University of Oslo), as a highly efficient acid catalyst.

In-water facile synthesis of poly-substituted 6-arylamino pyridines and 2-pyrrolidone derivatives using tetragonal nano-ZrO2 as reusable catalyst

Green synthesis of functionalized 6-arylamino pyridines and 2-pyrrolidinone derivatives using tetragonal ZrO₂ nanoparticles as reusable catalyst in aqueous ethanol.

Multicomponent one-pot synthesis of highly-functionalized pyrrole-3-carbonitriles in aqueous medium and their computational study

A one-pot green protocol involving four-components in aqueous medium is developed to synthesize highly-functionalized pyrroles in good yields. Two of the newly synthesized compounds were subjected to in silico analysis on the Pharm Mapper web-server and the human mitogen-activated protein kinase1 (MEK1) enzyme was identified as a potential target protein for these compounds. For target validation, MEK-1 inhibition was performed with two representative compounds (5g and 5h) using docking simulations. These functionalized pyrroles were also tested for their respective IC50 values on human cancer cell lines to evaluate their biocompatibility. Several of these functionalized pyrrole molecules were found to possess higher growth inhibition activity than standard doxorubicin and cisplatin.

BF3/nano-sawdust as a green, biodegradable and inexpensive catalyst for the synthesis of highly substituted dihydro-2-oxopyrroles

BF₃/nano-sawdust was used as a readily available, inexpensive, biodegradable and environmentally benign heterogeneous solid acid catalyst for the one-pot cascade synthesis of highly functionalized dihydro-2-oxypyrroles.

Efficient synthesis of functionalized spiro[indoline-3,4'-pyrrolo[3,4-b]pyridines] via one-pot three-component reaction

Diverse functionalized spiro[indoline-3,4'-pyrrolo[3,4-b]pyridines] were efficiently synthesized by the three-component reaction of 3-arylamino-1-methyl-H-pyrrole-2,5-dione, isatins and malononitrile (ethyl cyanoacetate) in ethanol in the presence of triethylamine. This reaction not only provided a convenient synthetic method for the construction of a versatile spirooxindole system, but also access to reactive β-enaminone and its derivatives for organic and medical chemistry.