One-pot construction of spirooxindole backbone via biocatalytic domino reaction

Multicomponent Reactions Using C,N-Binucleophilic Nature of Aminopyrazoles: Construction of Pyrazole-Fused Heterocycles

Synthesis of pyrazole-fused heterocycles has gained considerable attention in recent years due to their wide applications in medicinal chemistry. Aminopyrazoles are versatile building blocks for the synthesis of pyrazole-fused heterocycles by multicomponent reactions. Due to the presence of multiple reaction sites, they have fascinating chemical reactivity. Thus, they have been extensively used in multicomponent reactions for the construction of pyrazole-fused heterocycles. Although few review articles on the preparation and applications of aminopyrazoles are known in the literature, to date there is no dedicated review article on the construction of pyrazole-fused heterocycles exploring the reactivity of amino pyrazoles as C,N-binucleophiles in multicomponent reactions. Considering this, herein the multicomponent reactions for the construction of pyrazole-fused heterocycles exploring C,N-binucleophilic nature of amino pyrazoles have been reported.

Synthesis, antimicrobial activity and molecular docking studies of spiroquinoline-indoline-dione and spiropyrazolo-indoline-dione derivatives

Spiro[benzo[h]quinoline-7,3'-indoline]diones and spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]diones were efficiently synthesized via one-pot multi-component reactions under ultrasound-promoted conditions. Spiro[benzo[h]quinoline-7,3'-indoline]dione derivatives were successfully developed by the reaction of isatins, naphthalene-1-amine and 1,3-dicarbonyl compounds. The spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]dione derivatives were prepared by the reaction of isatins, 5-amino-1-methyl-3-pheylpyrazole, and 1,3-dicarbonyl compounds by using ( ±)-camphor-10-sulfonic acid as a catalyst in H₂O/EtOH (3:1 v/v) solvent mixture. The antibacterial activity of the synthesized compounds was evaluated against, Enterococcus faecalis, Staphylococcus aureus and Candida albicans. Compounds 4b, 4h, and 6h showed the strongest antimicrobial activity toward both bacteria. The MIC values of these compounds ranged from 375-3000 µg/mL. The effect of these compounds (4b, 4h, 6h) as a function of applied dose and time was investigated by a kinetic study, and the interaction with these antimicrobial results was simulated by a molecular docking study. We also used the docking approach with Covid-19 since secondary bacterial infections. Docking showed that indoline-quinoline hybrid compounds 4b and 4h exerted the strongest docking binding value against the active sites of 6LU7. In addition, the synthesized compounds had a moderate to good free radical scavenging activity.

Recent developments in promiscuous enzymatic reactions for carbon-nitrogen bond formation

Biocatalytic promiscuity is a new field of enzyme application in biochemistry, which has received much attention and has developed rapidly in recent years. The promiscuous biocatalysis has been promoted as a useful supplement to traditional strategy for the formation of C-heteroatom bonds. The generation of carbon-nitrogen (CN) bonds is an important issue in synthetic chemistry and is indispensable for the manufacturing of various pharmaceuticals and agrochemicals. Therefore, numerous efficient and reliable synthetic methods for the formation of CN bonds have been developed in recent years. Enzymatic CN bond forming reactions catalyzed by lipases, cytochrome P450 monooxygenases, glycosyltransferases, amine dehydrogenases, proteases, acylases, amylases and halohydrin dehalogenases are well established for synthetic purposes. This review introduces the recent progress in the construction of CN bonds using promiscuous enzymes.

Recent Advances in Multicomponent Reactions Catalysed under Operationally Heterogeneous Conditions

Multicomponent reactions (MCRs) have been gaining significance and attention over the past decade because of their ability to furnish complex products by using readily available and simple starting materials while simultaneously eliminating the need to separate and purify any intermediates. More so, most of these products have been found to exhibit diverse biological activities. Another paradigm shift which has occurred contemporarily is the switch to heterogeneous catalysis, which results in additional benefits such as the reduction of waste and an increase in the safety of the process. More importantly, it allows the user to recover and reuse the catalyst for multiple runs. In summary, both methodologies adhere to the principles of green chemistry, a philosophy which needs to become overarchingly enshrined. The plethora of reactions and catalysts which have been developed gives hope that chemists are slowly changing their ideology. As a result, this review attempts to discuss multicomponent reactions catalysed by operationally heterogeneous catalysts in the past 10 years. In this review, a further distinction is made between the MCRs which lead to the formation of heterocycles and those which do not.

Engaging Isatins in Multicomponent Reactions (MCRs) - Easy Access to Structural Diversity

Multicomponent reactions (MCRs) are a valuable tool in diversity-oriented synthesis. Its application to privileged structures is gaining relevance in the fields of organic and medicinal chemistry. Isatin, due to its unique reactivity, can undergo different MCRs, affording multiple interesting scaffolds, namely oxindole-derivatives (including spirooxindoles, bis-oxindoles and 3,3-disubstituted oxindoles) and even, under certain conditions, ring-opening reactions occur that leads to other heterocyclic compounds. Over the past few years, new methodologies have been described for the application of this important and easily available starting material in MCRs. In this review, we explore these novelties, displaying them according to the structure of the final products obtained.

Bio-Catalysis in Multicomponent Reactions

Enzyme catalysis is a very active research area in organic chemistry, because biocatalysts are compatible with and can be adjusted to many reaction conditions, as well as substrates. Their integration in multicomponent reactions (MCRs) allows for simple protocols to be implemented in the diversity-oriented synthesis of complex molecules in chemo-, regio-, stereoselective or even specific modes without the need for the protection/deprotection of functional groups. The application of bio-catalysis in MCRs is therefore a welcome and logical development and is emerging as a unique tool in drug development and discovery, as well as in combinatorial chemistry and related areas of research.

Design, synthesis and evaluation of new chromone-derived aminophosphonates as potential acetylcholinesterase inhibitor

A series of novel N-substituted α-aminophosphonates-bearing chromone moiety were synthesized and evaluated for acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) activities and antioxidant properties. Porcine pancreatic lipase was employed as a catalyst. Inhibitory activity against AChE ranged between 0.103 and 5.781 µM, whereas for BuChE, activities ranged between 8.619 and 18.789 µM. The results show that among the various synthesized compounds, strongest AChE inhibition was found for the compound containing aliphatic amine analogs, while in case of BuChE, aromatic amines showed better activity as compared to aliphatic amines. Compound 4j was found to be the most potent inhibitor of AChE with an IC₅₀ value of 0.103 ± 0.24 μM and inhibited AChE through mixed-type inhibition. Compound 4j was twofolds more potent than tacrine, 35-folds potent than galantamine and 50-folds potent than rivastigmine. Also, docking study revealed that compound 4j binds to both the peripheral anionic site and catalytic anionic site of AChE and BuChE. The antioxidant activities of synthesized compounds were performed against 2,2-diphenyl-1-picrylhydrazyl and hydrogen peroxide scavenging. DNA nicking activity of selected compounds also suggested that the compounds do not harm plasmid DNA pBR322. Compound 4j also showed significant DNA damage protection activity. Novel N-substituted α-aminophosphonates bearing chromone moiety were synthesized and evaluated for anti-acetylcholinesterase, anti-butyrylcholinesterase, antioxidant and DNA damage activities.

5-Amino-pyrazoles: potent reagents in organic and medicinal synthesis

5-Amino-pyrazoles have proven to be a class of fascinating and privileged organic tools for the construction of diverse heterocyclic or fused heterocyclic scaffolds. This review presents comprehensively the applications of 5-amino-pyrazoles as versatile synthetic building blocks in the synthesis of remarkable organic molecules with an emphasis on versatile functionalities. Following a brief introduction of synthesis methods, planning strategies to construct organic compounds, particularly diverse heterocyclic scaffolds, such as poly-substituted heterocyclic compounds and fused heterocyclic compounds via 5-amino-pyrazoles, have been summarized. Fused heterocycles are classified as bicyclic, tricyclic, tetracyclic, and spiro-fused pyrazole derivatives. These outstanding compounds synthesized via wide variety of approaches include conventional reactions, one-pot multi-component reactions, cyclocondensation, cascade/tandem protocols, and coupling reactions. 5-Amino-pyrazoles represent a class of promising functional reagents, similar to the biologically active compounds, highlighted with diverse applications especially in the field of pharmaceutics and medicinal chemistry. Notably, this critical review covers the articles published from 1981 to 2018.