Ugi Multicomponent Reaction Research Articles

Leveraging the Potential of Iqbal MCR: An Efficient Synthetic Route to Structurally Complex Tripeptidyl Ketones via Sequential Iqbal‐3CR/Ugi‐4CR

AbstractHighlighting the potential of Iqbal multicomponent reaction (MCR), a streamlined two‐step MCR synthetic strategy is proposed for the rapid assembly of structurally complex tripeptidyl ketones, which are valuable building blocks for developing novel peptidomimetics. The approach utilizes consecutive Iqbal MCR and Ugi MCR under mild room temperature conditions, eliminating the need for laborious column chromatography purification. This work demonstrates Iqbal MCR's propensity to generate a diverse library of N‐(3‐oxopropyl) carboxamides containing carboxyl functionality, which can be readily elaborated further to tripeptidyl ketones through subsequent Ugi MCR.

Efficient Capture and Release of the Rare-Earth Element Neodymium in Aqueous Solution by Recyclable Covalent Organic Frameworks.

Rare-earth elements (REEs) are present in a broad range of critical materials. The development of solid adsorbents for REE capture could enable the cost-effective recycling of REE-containing magnets and electronics. In this context, covalent organic frameworks (COFs) are promising candidates for REE adsorption due to their exceptionally high surface area. Despite having attractive physical properties, COFs are heavily underutilized for REE capture applications due to their limited lifecycle in aqueous acidic environments, as well as synthetic challenges associated with the incorporation of ligands suitable for REE capture. Here, we show how the Ugi multicomponent reaction can be leveraged to postsynthetically modify imine-based COFs for the introduction of a diglycolic acid (DGA) moiety, an efficient scaffold for REE capture. The adsorption capacity of the DGA-functionalized COF was found to be more than 40 times higher than that of the pristine imine COF precursor and more than four times higher than that of the next-best reported DGA-functionalized solid support. This rationally designed COF has appealing characteristics of high adsorption capacity, fast and efficient capture and release of the REE ions, and reliable recyclability, making it one of the most promising adsorbents for solid-liquid REE ion extractions reported to date.

Atom-economical synthesis, antimicrobial assessment, and molecular dynamics of indole-derived peptidomimetics for improved therapeutic insights

The emergence of multi-drug resistant strains spanning bacteria, fungi, viruses, and parasites poses a severe threat to public health and the economy. Tackling antimicrobial resistance requires swiftly identifying new agents with unique mechanisms. Multicomponent reactions offer a vital method to produce diverse analogs in various heterocyclic compounds, with broad medicinal applications. This study synthesized a range of peptidomimetics using isocyanide-based multicomponent Ugi reactions. These analogs were screened for antimicrobial efficacy against both Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Staphylococcus aureus IGMS-01), with ampicillin as a reference antibiotic, and for antifungal activity against Candida albicans, using fluconazole as a reference. The compounds showed moderate but significant efficacy across all tests. Docking analysis with microbial proteins revealed notable binding affinities for peptidomimetics 5h (N-(2-(1H-indol-3-yl)ethyl)-N-(1-(4-chlorophenyl)-2-(cyclohexylamino)-2-oxoethyl)stearamide) and 5i (N-(2-(1H-indol-3-yl)ethyl)-N-(1-(4-chlorophenyl)-2-(cyclohexylamino)-2-oxoethyl)oleamide). Molecular dynamics simulations confirmed stable interactions between the ligands and proteins. Furthermore, the long alkyl chain analogs demonstrated the ability to form organo/hydrogels, facilitating the incorporation of silver sulfadiazine for controlled antimicrobial release. This innovative approach enhances drug dispersion within the gel structure, effectively inhibiting microbial growth. These findings highlight the potential of these adaptable materials to advance drug development efforts in the foreseeable future.

Exploring Anticancer Potential: Synthesis and Assessment of the Biological Activity of Novel Synthesized Pyrazinoic Acid Derivatives

AbstractOne of the most effective approaches to discovering novel drugs for cancer treatment involves the exploration of new synthetic compounds. The pyrazinoic acid or pyrazine‐2‐carboxylic acid (PA)‐derivative compounds can be explored as a new anticancer agent due to their nitrogenous heteroaromatic ring. In this study, ten novels PA derivatives were synthesized by Ugi multicomponent reaction and characterized using IR, NMR, and mass spectroscopy. The cytotoxic activity was assayed in three different cancer cell lines, including colon (HT‐29), lung (A549), and breast (MCF‐7). The U10 was the most potent compound, exhibiting moderate cytotoxicity with IC50 of 8.26 μM, 8.23 μM, and 22.58 μM against HT‐29, A549, and MCF‐7 cell lines, respectively. In addition, the effect of U10 exposure in the MRC‐5 cell line as a non‐tumoral lung cell line showed a selectivity index of 3.76. The apoptotic activity and intracellular ROS level induction of U10 were assayed in MCF‐7 cells. The results demonstrated that apoptosis increases from 23.94 % at 10 μM to 36.8 % at 25 μM. Intracellular ROS level assay showed that U10 was able to significantly increase intracellular ROS by increasing the concentration. Molecular docking was utilized to predict the binding sites and interactions between the synthesized compound and DNA, as well as the Bcl‐2 apoptosis regulator.

Modular Divergent Synthesis of Indole Alkaloid Derivatives by an Atypical Ugi Multicomponent Reaction.

We present an Ugi multicomponent approach to explore the chemical space around Aspidosperma-type monoterpene indole alkaloids. By variation of the isocyanide and carboxylic acid inputs we demonstrate the rapid generation of molecular diversity and the possibility to introduce handles for further modification. The key Ugi three-component reaction showed full diastereoselectivity towards the cis-fused ring system, which can be rationalized by DFT calculations that moreover indicate that the reaction proceeds via a Passerini-type hydrogen bonding mechanism. Several post-Ugi modifications were also performed, including Pictet-Spengler cyclization to highly complex nonacyclic natural product hybrid scaffolds.

Exploiting the Different Nucleophilicity of the Isocyano Group: A Strategy for the Isocyanide Functionalization.

By exploiting the different nucleophilicity of aromatic and aliphatic isocyanides, we selectively react aliphatic isocyano groups while preserving aromatic ones in Passerini and Ugi multicomponent reactions. This simple approach allows the synthesis of α-acyloxy carboxamides or α-acylamino carboxamides possessing one or two isocyanide groups, which are challenging to achieve through traditional formylation and dehydration protocols. These analogues have the potential to serve as valuable building blocks with diverse applications.

Novel 2,5-Diketopiperazines with In Vitro Activities against Protozoan Parasites of Tropical Diseases.

Malaria, Chagas disease, and leishmaniasis are tropical diseases caused by protozoan parasites of the genera Plasmodium, Trypanosoma and Leishmania, respectively. These diseases constitute a major burden on public health in several regions worldwide, mainly affecting low-income populations in economically poor countries. Severe side effects of currently available drug treatments and the emergence of resistant parasites need to be addressed by the development of novel drug candidates. Natural 2,5-Diketopiperazines (2,5-DKPs) constitute N-heterocyclic secondary metabolites with a wide range of biological activities of medicinal interest. Its structural and physicochemical properties make the 2,5-DKP ring a versatile, peptide-like, and stable pharmacophore attractive for synthetic drug design. In the present work, twenty-three novel synthetic 2,5-DKPs, previously synthesized through the versatile Ugi multicomponent reaction, were assayed for their anti-protozoal activities against P. falciparum, T. cruzi, and L. infantum. Some of the 2,5-DKPs have shown promising activities against the target protozoans, with inhibitory concentrations (IC50) ranging from 5.4 to 9.5 µg/mL. The most active compounds also show low cytotoxicity (CC50), affording selectivity indices ≥ 15. Results allowed for observing a clear relationship between the substitution pattern at the aromatic rings of the 2,5-DKPs and their corresponding anti-Plasmodium activity. Finally, calculated drug-like properties of the compounds revealed points for further structure optimization of promising drug candidates.

Site-Selective Protein Conjugation by a Multicomponent Ugi Reaction.

The chemical bioconjugation of proteins has seen tremendous applications in the past decades, with the booming of antibody-drug conjugates and their use in oncology. While genetic engineering has permitted to produce bespoke proteins featuring key (un-)natural amino acid residues poised for site-selective modifications, the conjugation of native proteins is riddled with selectivity issues. Chemoselective strategies are plentiful and enable the precise modification of virtually any residue with a reactive side-chain; site-selective methods are less common and usually most effective on small and medium-sized proteins. In this context, we studied the application of the Ugi multicomponent reaction for the site-selective conjugation of amine and carboxylate groups on proteins, and antibodies in particular. Through an in-depth mechanistic methodology work supported by peptide mapping studies, we managed to develop a set of conditions allowing the highly selective modification of antibodies bearing N-terminal glutamate and aspartate residues. We demonstrated that this strategy did not alter their affinity toward their target antigen and produced an antibody-drug conjugate with subnanomolar potency. Excitingly, we showed that the high site selectivity of our strategy was maintained on other protein formats, especially on anticalins, for which directed mutagenesis helped to highlight the key importance of a single lysine residue.

Recent developments in the total synthesis of natural products using the Ugi multicomponent reactions as the key strategy.

The total syntheses of selected natural products using different versions of the Ugi multicomponent reaction is reviewed on a case-by-case basis. The revision covers the period 2008-2023 and includes detailed descriptions of the synthetic sequences, the use of state-of-the-art chemical reagents and strategies, as well as the advantages and limitations of the transformation and some remedial solutions. Relevant data on the isolation and bioactivity of the different natural targets are also briefly provided. The examples clearly evidence the strategic importance of this transformation and its key role in the modern natural products synthetic chemistry toolbox. This methodology proved to be a valuable means for easily building molecular complexity and efficiently delivering step-economic syntheses even of intricate structures, with a promising future.

Eudragit® L100 Post-Modification via Ugi Multicomponent Reaction

This work investigated the post-modification of commercial poly(methyl mechacrylate-coacrylic acid) using the versatile multicomponent Ugi reaction. This reaction introduces diverse functionalities to tailor the polymer properties effectively. The commercial copolymer which is known for biocompatibility and drug delivery application was subjected to the Ugi reaction, altering its chemical structure. The structure of the modified polymer was checked by Fourier transform infrared spectroscopic and nuclear magnetic resonance and thermal characterizations, confirming successful Ugi component integration. Additionally, gel permeation chromatography assessed molecular weight changes. Results revealed enhanced thermal stability of the modified polymers compared to unmodified polymer, potentially advantageous in high-temperature applications. In summary, the study demonstrates efficient poly(methyl mechacrylate-co-acrylic acid) post-modification through a multicomponent Ugi reaction, yielding tailored polymers. Comprehensive spectroscopic, thermal, and gel permeation analyses shed light on structural changes and improved stability, pivotal for innovative applications like drug delivery.

Dibenzyl amine as an ammonia surrogate in the Ugi tetrazoles: Design, synthesis and impactful antioxidant activity

In this study, we develop novel tetrazole compounds based on dibenzyl amine (DBA) and investigate their potential as antioxidants. The aforementioned compounds were synthesised by the Ugi multicomponent reaction, which involved the simultaneous addition of four systems, i.e., DBA, cyclohexyl isocyanide, TMSN3 and aromatic aldehyde in ethanol media under RT. The different isocyanides effect in the progress of the TMSN3 based Ugi reaction was studied. The tetrazoles that were changed with DBA were studied using several techniques, including FTIR, 1H NMR, 13C NMR, and MS. The antioxidant properties of the produced compounds (4a-4j) were subsequently tested in a controlled laboratory setting using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical assay. When compared to ascorbic acid, the antioxidant efficacy of all of the produced compounds was high. The obtained results for all prepared compounds were good as an antioxidant in comparison with ascorbic acid. The electron withdrawing effect of the substituents (halogens and nitro groups) on the aromatic side enhanced the antioxidant activity of the newly derived motifs. Their molecular docking investigation with the myeloperoxidase (MPO) enzyme revealed a strong relationship between their binding modalities and the antioxidant properties they displayed.

Ugi 5-center-4-component reaction of α-amino aldehydes and its application in synthesis of 2-oxopiperazines

A synthetic route leading to densely functionalized 2-oxopiperazines is presented. The strategy employs a 5-center-4-component variant of Ugi multicomponent reaction followed by a deprotection/cyclization sequence. N-Boc-α-amino aldehydes were used for the first time as carbonyl components in a key Ugi 5-center-4-component reaction (U-5C-4CR). It is shown that the presented synthetic route can lead to rigid, heterocyclic scaffolds, as demonstrated by the synthesis of tetrahydro-2H-pyrazino[1,2-a]pyrazine-3,6,9(4H)-trione β-turn mimetic and derivatives of 1,6-dioxooctahydropyrrolo[1,2-a]pyrazine and 3,8-dioxohexahydro-3H-oxazolo[3,4-a]pyrazine.Graphical abstract

Finding the Best Proposed Mechanism for Ugi Multi-Component Reaction by DFT Study

The one-pot four-component condensation of benzoic acid (R1), aniline (R2), benzaldehyde (R3), and 2-isocyano-2-methylpropane was investigated at the B3LYP/6-311G** level to explore the reaction mechanism as a theoretical study. All routes were studied and structure of intermediates (IM) was optimized and all of the respective transition states (TS) were found. The calculation results proved that the proposed mechanism consists of eight steps that rate determining the state is nucleophilic attack of isocyanide to benzaldehyde.

Multicomponent synthesis and photophysical study of novel α,β-unsaturated carbonyl depsipeptides and peptoids.

Multicomponent reactions were performed to develop novel α,β-unsaturated carbonyl depsipeptides and peptoids incorporating various chromophores such as cinnamic, coumarin, and quinolines. Thus, through the Passerini and Ugi multicomponent reactions (P-3CR and U-4CR), we obtained thirteen depsipeptides and peptoids in moderate to high yield following the established protocol and fundamentally varying the electron-rich carboxylic acid as reactants. UV/Vis spectroscopy was utilized to study the photophysical properties of the newly synthesized compounds. Differences between the carbonyl-substituted chromophores cause differences in electron delocalization that can be captured in the spectra. The near UV regions of all the compounds exhibited strong absorption bands. Compounds P2, P5, U2, U5, and U7 displayed absorption bands in the range of 250-350nm, absorbing radiation in this broad region of the electromagnetic spectrum. A photostability study for U5 showed that its molecular structure does not change after exposure to UV radiation. Fluorescence analysis showed an incipient emission of U5, while U6 showed blue fluorescence under UV radiation. The photophysical properties and electronic structure were also determined by TD-DFT theoretical study.

General Strategy for Incorporation of Functional Group Handles into Covalent Organic Frameworks via the Ugi Reaction

The library of imine-linked covalent organic frameworks (COFs) has grown significantly over the last two decades, featuring a variety of morphologies, pore sizes, and applications. An array of synthetic methods has been developed to expand the scope of the COF functionalities; however, most of these methods were designed to introduce functional scaffolds tailored to a specific application. Having a general approach to diversify COFs via late-stage incorporation of functional group handles would greatly facilitate the transformation of these materials into platforms for a variety of useful applications. Herein, we report a general strategy to introduce functional group handles in COFs via the Ugi multicomponent reaction. To demonstrate the versatility of this approach, we have synthesized two COFs with hexagonal and kagome morphologies. We then introduced azide, alkyne, and vinyl functional groups, which could be readily utilized for a variety of post-synthetic modifications. This facile approach enables the functionalization of any COFs containing imine linkages.

Luminescent furo[2,3-c]isoquinolines as fluorophores - Tuning the luminophore by donor substitution

A new library of the uncommon furo[2,3-c]isoquinoline scaffold has been synthesized by coupling the Ugi multicomponent reaction with a complex one-pot Pd-mediated double cyclization. The highly convergent and diversity-oriented approach has been exploited to introduce substituents with electron donor properties directly linked to the scaffold in the most representative positions 1 and/or 8. Moreover, the influence of an aromatic ring used as spacer between the scaffold and the electron donor substituent, as well as the substitution of the phenyl substituent in position 1 with a thiophene, on the photophysical properties have been investigated. Upon UV excitation part of the new molecules are intensively blue luminescent but for an amino donor substituent a significant switch to green emitters has been observed even upon eyesight. The electronic structure has been semiquantitatively rationalized by DFT and (TD)DFT calculations.

3D-Printing of Capsule Devices as Compartmentalization Tools for Supported Reagents in the Search of Antiproliferative Isatins.

The application of high throughput synthesis methodologies in the generation of active pharmaceutical ingredients (APIs) currently requires the use of automated and easily scalable systems, easy dispensing of supported reagents in solution phase organic synthesis (SPOS), and elimination of purification and extraction steps. The recyclability and recoverability of supported reagents and/or catalysts in a rapid and individualized manner is a challenge in the pharmaceutical industry. This objective can be achieved through a suitable compartmentalization of these pulverulent reagents in suitable devices for it. This work deals with the use of customized polypropylene permeable-capsule devices manufactured by 3D printing, using the fused deposition modeling (FDM) technique, adaptable to any type of flask or reactor. The capsules fabricated in this work were easily loaded "in one step" with polymeric reagents for use as scavengers of isocyanides in the work-up process of Ugi multicomponent reactions or as compartmentalized and reusable catalysts in copper-catalyzed cycloadditions (CuAAC) or Heck palladium catalyzed cross-coupling reactions (PCCCRs). The reaction products are different series of diversely substituted isatins, which were tested in cancerous cervical HeLa and murine 3T3 Balb fibroblast cells, obtaining potent antiproliferative activity. This work demonstrates the applicability of 3D printing in chemical processes to obtain anticancer APIs.

Ugi Four-Component Reactions Using Alternative Reactants.

The Ugi four-component reaction (Ugi-4CR) undoubtedly is the most prominent multicomponent reaction (MCRs) that has sparked organic chemists' interest in the field. It has been widely used in the synthesis of diverse heterocycle molecules such as potential drugs, natural product analogs, pseudo peptides, macrocycles, and functional materials. The Ugi-4CRs involve the use of an amine, an aldehyde or ketone, an isocyanide, and a carboxylic acid to produce an α-acetamido carboxamide derivative, which has significantly advanced the field of isocyanide-based MCRs. The so-called intermediate nitrilium ion could be trapped by a nucleophile such as azide, N-hydroxyphthalimide, thiol, saccharin, phenol, water, and hydrogen sulfide instead of the original carboxylic acid to allow for a wide variety of Ugi-type reactions to occur.β In addition to isocyanide, there are alternative reagents for the other three components: amine, isocyanide, and aldehyde or ketone. All these alternative components render the Ugi reaction an aptly diversity-oriented synthesis of a myriad of biologically active molecules and complex scaffolds. Consequently, this review will delve deeper into alternative components used in the Ugi MCRs, particularly over the past ten years.

Efficient AntiMycolata Agents by Increasing the Lipophilicity of Known Antibiotics through Multicomponent Reactions.

New antibiotic agents were prepared using Povarov and Ugi multicomponent reactions upon the known drugs sulfadoxine and dapsone. The prepared derivatives, with increased lipophilicity, showed improved efficiency against Mycolata bacteria. Microbiological guidance for medicinal chemistry is a powerful tool to design new and effective antimicrobials. In this case, the readily synthesized compounds open new possibilities in the search for antimicrobials active on mycolic acid-containing bacteria.

Charge controlled interactions between DNA-modified silica nanoparticles and fluorosurfactants in microfluidic water-in-oil droplets.

Microfluidic droplets are an important tool for studying and mimicking biological systems, e.g., to examine with high throughput the interaction of biomolecular components and the functionality of natural cells, or to develop basic principles for the engineering of artificial cells. Of particular importance is the approach to generate a biomimetic membrane by supramolecular self-assembly of nanoparticle components dissolved in the aqueous phase of the droplets at the inner water/oil interface, which can serve both to mechanically reinforce the droplets and as an interaction surface for cells and other components. While this interfacial assembly driven by electrostatic interaction of surfactants is quite well developed for water/mineral oil (W/MO) systems, no approaches have yet been described to exploit this principle for water/fluorocarbon oil (W/FO) emulsion droplets. Since W/FO systems exhibit not only better compartmentalization but also gas solubility properties, which is particularly crucial for live cell encapsulation and cultivation, we report here the investigation of charged fluorosurfactants for the self-assembly of DNA-modified silica nanoparticles (SiNP-DNA) at the interface of microfluidic W/FO emulsions. To this end, an efficient multicomponent Ugi reaction was used to synthesize the novel fluorosurfactant M4SURF to study the segregation and accumulation of negatively charged SiNP-DNA at the inner interface of microfluidic droplets. Comparative measurements were performed with the negatively charged fluorosurfactant KRYTOX, which can also induce SiNP-DNA segregation in the presence of cations. The segregation dynamics is characterized and preliminary results of cell encapsulation in the SiNP-DNA functionalized droplets are shown.