Recent Advances in One-Pot Modular Synthesis of 2-Quinolones

Iron-catalyzed synthesis of substituted 3-arylquinolin-2(1H)-ones via an intramolecular dehydrogenative coupling of amido-alcohols

Here we report an iron-complex-catalyzed synthesis of various mono- and di-substituted quinolin-2(1H)-ones achieved via the intramolecular acceptorless dehydrogenative cyclization of amido-alcohols. This approach for the synthesis of N-heterocycles has provided access to underdescribed disubstituted quinolinones and represents an alternative to the well-known palladium-catalyzed coupling reactions.

Pallado-Catalyzed Cascade Synthesis of 2-Alkoxyquinolines from 1,3-Butadiynamides

A novel synthesis strategy to access 2-alkoxyquinoline derivatives via a palladium-driven cascade reaction is disclosed. Unlike classic methods based on the alkylation of 2-quinolones with alkyl halides, the present method benefits from the de novo assembly of the quinoline core starting from 1,3-butadiynamides. Palladium-catalyzed reaction cascades with N-(2-iodophenyl)-N-tosyl-1,3-butadiynamides and primary alcohols as external nucleophiles proceed under mild reaction conditions and selectively deliver a variety of differently functionalized 4-alkenyl 2-alkoxyquinolines in a single batch transformation.

Biological activity of natural 2-quinolinones

While natural products have undeniably played a crucial role in drug discovery, challenges such as limited availability and complex synthesis methods have hindered the identification of lead compounds. At the core of numerous natural and synthetic compounds, each displaying distinct biological behaviours, lies the foundational structure of 2-quinolinone. Compounds with this structural motif exhibit a broad range of effects in different tissues. Furthermore, specific members showcase therapeutic potential for various disorders. Despite the significance of these compounds, the current review literature has not provided a comprehensive overview, underscoring the essential contribution of this article in exploring their biological functions. This study examines the biological activity of selected 2-quinolinone alkaloids across diverse organisms, unveiling their potential as a source of innovative bioactive natural products.

Natural 3,4-Dihydro-2(1H)-quinolinones - part III: biological activities

Natural products have played a crucial role in drug discovery, but their development is hindered by challenges such as inadequate availability and complex synthesis methods. However, both natural and synthetic compounds that have the core structure of 3,4-dihydro-2(1H)-quinolinone, also known as 2-oxo-1,2,3,4-tetrahydroquinoline (2O-THQ), display a diverse array of effects in both central and peripheral tissues, with some showing therapeutic potential in treating various disorders. Despite the significance of this family of compounds, the current literature lacks comprehensive coverage of their biological functions. This article aims to address this gap by extensively reviewing the biological activities of 2O-THQ alkaloids from diverse organisms and exploring their potential to serve as a source of innovative bioactive natural products.

Discovery of novel quinolin-2-one derivatives as potential GSK-3β inhibitors for treatment of Alzheimer's disease: Pharmacophore-based design, preliminary SAR, in vitro and in vivo biological evaluation

Recently, glycogen synthase kinase-3β (GSK-3β) has been considered as a critical factor implicated in Alzheimer's disease (AD). In a previous work, a 3D pharmacophore model for GSK-3β inhibitors was created and the results suggested that derivative ZINC67773573, VIII, may provide a promising lead for developing novel GSK-3β inhibitors for the AD's treatment. Consequently, in this work, novel series of quinolin-2-one derivatives were synthesized and assessed for their GSK-3β inhibitory properties. In vitro screening identified three compounds: 7c, 7e and 7f as promising GSK-3β inhibitors. Compounds 7c, 7e and 7f were found to exhibit superior inhibitory effect on GSK-3β with IC50 value ranges between 4.68 ± 0.59 to 8.27 ± 0.60 nM compared to that of staurosporine (IC50 = 6.12 ± 0.74 nM). Considerably, compounds 7c, 7e and 7f effectively lowered tau hyperphosphorylated aggregates and proving their safety towards the SH-SY5Y and THLE2 normal cell lines. The most promising compound 7c alleviated cognitive impairments in the scopolamine-induced model in mice. Compound 7c's activity profile, while not highly selective, may provide a starting point and valuable insights into the design of multi-target inhibitors. According to the ADME prediction results, compounds 7c, 7e and 7f followed Lipinski's rule of five and could almost permeate through the BBB. Molecular docking simulations showed that these compounds are well accommodated in the ATP binding site interacting by its quinoline-2-one ring through hydrogen bonding with the key amino acids Asp133 and Val135 at the hinge region. The findings of this study suggested that these new compounds may have potential as anti-AD drugs targeting GSK-3β.

Natural 3,4-dihydro-2(1h)-quinolinones- Part II: animal, bacterial, and fungal sources

While natural products have undoubtedly played a pivotal role in drug discovery, their potential as lead compounds has been hindered by challenges such as limited accessibility and complex synthesis processes. At the core of numerous natural and synthetic compounds, each exhibiting remarkable biological traits, lies the foundational structure of 3,4-dihydro-2(1H)-quinolinone, also recognised as 2-oxo-tetrahydroquinoline (2 O-THQ). This article extensively examines the occurrence of 2 O-THQ alkaloids across diverse organisms including animals, fungi, and bacteria, exploring their capacity to serve as a source for innovative bioactive natural products. Despite the undeniable significance of these compounds, the existing body of review literature has yet to provide comprehensive coverage, underscoring the pivotal contribution of this present article in investigating their prevalence in nature.

Design, synthesis, and molecular modeling studies of novel 2-quinolone-1,2,3-triazole-α-aminophosphonates hybrids as dual antiviral and antibacterial agents

With the aim to identify new antiviral agents with antibacterial properties, a series of 2-quinolone-1,2,3-triazole derivatives bearing α-aminophosphonates was synthesized and characterized by 1H NMR, 13C NMR, 31P NMR, single crystal XRD and HRMS analyses. These compounds were examined against five RNA viruses (YFV, ZIKV, CHIKV, EV71 and HRV) from three distinct families (Picornaviridae, Togaviridae and Flaviviridae) and four bacterial strains (S. aureus, E. feacalis, E. coli and P. aeruginosa). The α-aminophosphonates 4f, 4i, 4j, 4k, 4p and 4q recorded low IC50 values of 6.8-10.91 μM, along with elevated selectivity indices ranging from 2 to more than 3, particularly against YFV, CHIKV and HRV-B14. Besides, the synthesized compounds were generally more sensitive toward Gram-positive bacteria, with the majority of them displaying significant potency against E. feacalis. Specifically, an excellent anti-enterococcus activity was obtained by compound 4q with MIC and MBC values of 0.03 μmol/mL, which were 8.7 and 10 times greater than those of the reference drugs ampicillin and rifampicin, respectively. Also, compounds 4f, 4p and 4q showed potent anti-staphylococcal activity with MIC values varying between 0.11 and 0.13 μmol/mL, compared to 0.27 μmol/mL for ampicillin. The results from DFT and molecular docking simulations were in agreement with the biological assays, proving the binding capability of hybrids 4f, 4i, 4j, 4k, 4p and 4q with viral and bacterial target enzymes through hydrogen bonds and other non-covalent interactions. The in silico ADME/Tox prediction revealed that these molecules possess moderate to good drug-likeness and pharmacokinetic properties, with a minimal chance of causing liver toxicity or carcinogenic effects.

Ring Expansion of Isatins via 1,2-Phospha-Brook Rearrangement: A Route to the Synthesis of 2-Quinolinone-Derived p-Quinone Methides

A Lewis acid-mediated one-carbon homologation approach to installing a 2-quinolinone core embedded with para-quinone methides, in a high yield of up to 92%, and with high regioselectivity has been developed. Also, post-synthetic modifications, including C-P, C-S, and C-C bond formations, have been demonstrated by the 1,6-addition of suitable nucleophiles. Further, cyclopropanation of 2-quinolinone-embedded p-QM is also demonstrated affording a contiguous quaternary spiro center.

Silver-catalysed double decarboxylative addition-cyclisation-elimination cascade sequence for the synthesis of quinolin-2-ones

An atom-efficient silver-catalysed double carboxylative strategy for the one-step synthesis of quinolin-2-ones via an addition-cyclisation-elimination cascade sequence of oxamic acids to acrylic acids, mediated either thermally or photochemically, is reported. The reaction was applicable to the synthesis of a broad range of quinolin-2-ones and featured a double-disconnection approach that constructed the quinolin-2-one core via the formal and direct addition of a C(sp²)-H/C(sp²)-H olefin moiety to a phenylformamide precursor.

Diversity-Oriented Synthesis: Amino Acetophenones as Building Blocks for the Synthesis of Natural Product Analogs

Diversity-Oriented Synthesis (DOS) represents a strategy to obtain molecule libraries with diverse structural features starting from one common compound in limited steps of synthesis. During the last two decades, DOS has become an unmissable strategy in organic synthesis and is fully integrated in various drug discovery processes. On the other hand, natural products with multiple relevant pharmacological properties have been extensively investigated as scaffolds for ligand-based drug design. In this article, we report the amino dimethoxyacetophenones that can be easily synthesized and scaled up from the commercially available 3,5-dimethoxyaniline as valuable starting blocks for the DOS of natural product analogs. More focus is placed on the synthesis of analogs of flavones, coumarins, azocanes, chalcones, and aurones, which are frequently studied as lead compounds in drug discovery.

Synthesis of N-CF3 Alkynamides and Derivatives Enabled by Ni-Catalyzed Alkynylation of N-CF3 Carbamoyl Fluorides

The expansion of chemical space associated with ubiquitous motifs is key to unleash new properties and functions. In this context, alkynamides, prevalent in numerous drugs and materials, represent an untapped resource. We herein report the first synthetic access to N-trifluoromethyl alkynamides. Our strategy relies on a mild and operationally simple Ni-catalyzed coupling of N-CF₃ carbamoyl fluorides with alkynyl silanes. The synthesized N-CF₃ alkynamides proved to be highly robust and readily functioned as a platform to unlock access to valuable derivatives, such as N-CF₃ decorated alkenyl amides, oxindoles, or quinolones, all of which were inaccessible to date.