Rhodium-Catalyzed Selective C−H Bond Functionalization of Quinolines
01 Oct 2020-Asian Journal of Organic Chemistry (John Wiley & Sons, Ltd)-Vol. 9, Iss: 10, pp 1502-1518
About: This article is published in Asian Journal of Organic Chemistry.The article was published on 2020-10-01. It has received 25 citations till now. The article focuses on the topics: Rhodium & Catalysis.
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TL;DR: In this article, the authors elaborate on recent developments in the highly challenging functionalization of C-H bonds on the less-reactive benzenoid core of indoles and quinolines.
Abstract: The site-selective C-H bond functionalization of heteroarenes can eventually provide chemists with great techniques for editing and building complex molecular scaffolds. During the past decade, benzo-fused N-heterocycles such as indoles and quinolines have been among the most widely investigated organic templates. Early developments have led to site-selective C-H bond functionalization on the pyrrole and pyridine cores of indoles and quinolines; however, C-H functionalization on the benzenoid ring has remained a great challenge in catalysis. In this review, we elaborate on recent developments in the highly challenging functionalization of C-H bonds on the less-reactive benzenoid core of indoles and quinolines. These findings are mainly described as selective directing group assisted strategies, remote C-H functionalization techniques and their reaction mechanisms. The underlying principle in each strategy is elucidated, which aims to facilitate the design of a more advanced structure of heterocycles based on bioactive molecules, synthetic drugs, and material aspects. Moreover, the challenges and perspectives for catalytic C-H functionalization to access the arene backbone of indoles and quinolines are also proposed in the conclusion section.
61 citations
TL;DR: In this article , the authors have discussed the significance of inhibitory and antiviral activities of nitrogen, oxygen, and mixed (nitrogen - sulfur and nitrogen-oxygen) heterocyclic scaffolds that are published in the last seven years (2016-2022).
Abstract: Dengue is one of the most typical viral infection categorized in the Neglected Tropical Diseases (NTDs). It is transmitted via the female Aedes aegypti mosquito to humans and majorly puts risk to the lives of more than half of the world. Recent advancements in medicinal chemistry have led to the design and development of numerous potential heterocyclic scaffolds as antiviral drug candidates for the inhibition of the dengue virus (DENV). Thus, in this review, we have discussed the significance of inhibitory and antiviral activities of nitrogen, oxygen, and mixed (nitrogen - sulfur and nitrogen-oxygen) heterocyclic scaffolds that are published in the last seven years (2016–2022). Furthermore, we have also discussed the probable mechanisms of action and the diverse structure-activity relationships (SARs) of the heterocyclic scaffolds. In addition, this review has elaborately outlined the mechanism of viral infection and the life cycle of DENV in the host cells. The wide set of heterocycles and their SARs will aid in the development of pharmaceuticals that will allow the researchers to synthesize the promising anti-dengue drug candidate in the future. • Dengue is a critical viral infection under Neglected Tropical Diseases. • The molecular mechanism and life cycle of DENV infection have been elucidated. • The inhibitory effect of several heterocyclic Scaffolds on DENV has been outlined. • SAR of heterocycles on the DENV serotypes has been summarized.
16 citations
TL;DR: In this paper, the authors highlight some of the contemporary development toward constructing N-containing heterocycles and their direct functionalizations via transition metal catalysed C-H bond functionalizations based on migratory insertion of metal-carbenes and nitrenes.
Abstract: Nitrogen-containing heterocycles are widely found in various biologically active substrates, pharmaceuticals, natural products and organic materials. Consequently, the continuous effort has been devoted towards the development of straightforward, economical, environmentally acceptable, efficient and ingenious methods for the synthesis of various N-containing heterocycles and their functionalizations. Arguably, one of the most prominent direct strategy is regioselective C-H bond functionalizations which provide the step and atom economical approaches in the presence of suitable coupling partners. In this context, site-selective migratory insertion of metal carbenes/nitrenes to the desired C-H bonds has proven as a useful tool to access various functionalized nitrogen heterocycles. In this personal account, we highlight some of our contemporary development toward constructing N-containing heterocycles and their direct functionalizations via transition metal catalysed C-H bond functionalizations based on migratory insertion of metal-carbenes and nitrenes.
15 citations
TL;DR: The first [Cl2Ru(p-cymene)]2-catalyzed direct mono-arylation of unactivated C(sp3)-H bond of 8-methyl quinolines with aryl boronic acids to synthesize diarylmethane compounds is presented.
Abstract: The transition-metal-promoted C-H activation has become an efficient as well as atom-economic methodology for the synthesis of a wide array of organic molecules, but the cost of the metal catalyst and selectivity remain the major challenges Herein, the first [Cl2Ru(p-cymene)]2-catalyzed direct monoarylation of unactivated C(sp3)-H bonds of 8-methyl quinolines with arylboronic acids to synthesize diarylmethane compounds is presented The transformation shows a broad substrate scope with high chemoselectivity for the synthesis of 8-benzyl quinolines In the preliminary mechanistic studies, control experiments, deuterium labeling experiments, and kinetic studies have been performed
11 citations
TL;DR: In this article, an unprecedented I2/FeCl3-promoted cascade reaction of aryl methyl ketones with 8-aminoquinolines for the convenient synthesis of (E)-3-(2-acyl-1H-benzo[d]imidazol-4-yl)acrylaldehydes was developed by merging annulation with ring deconstruction.
9 citations
References
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TL;DR: The relevant mechanistic insights that enabled synthetic advances and distinguished the resulting transformations from other methods are emphasized and researchers will better understand the details of the aforementioned Rh-catalyzed C-H bond functionalization reactions, resulting in the design of more efficient and robust catalysts, expanded substrate scope, and new transformations.
Abstract: Nitrogen heterocycles are present in many compounds of enormous practical importance, ranging from pharmaceutical agents and biological probes to electroactive materials. Direct functionalization of nitrogen heterocycles through C−H bond activation constitutes a powerful means of regioselectively introducing a variety of substituents with diverse functional groups onto the heterocycle scaffold. Working together, our two groups have developed a family of Rh-catalyzed heterocycle alkylation and arylation reactions that are notable for their high level of functional-group compatibility. This Account describes our work in this area, emphasizing the relevant mechanistic insights that enabled synthetic advances and distinguished the resulting transformations from other methods. We initially discovered an intramolecular Rh-catalyzed C-2 alkylation of azoles by alkenyl groups. That reaction provided access to a number of di-, tri-, and tetracyclic azole derivatives. We then developed conditions that exploited mic...
860 citations
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TL;DR: In pregnancy, quinine continues to play a critical role in the management of malaria, especially in the first trimester, and it will remain a mainstay of treatment until safer alternatives become available.
Abstract: Quinine remains an important anti-malarial drug almost 400 years after its effectiveness was first documented However, its continued use is challenged by its poor tolerability, poor compliance with complex dosing regimens, and the availability of more efficacious anti-malarial drugs This article reviews the historical role of quinine, considers its current usage and provides insight into its appropriate future use in the treatment of malaria In light of recent research findings intravenous artesunate should be the first-line drug for severe malaria, with quinine as an alternative The role of rectal quinine as pre-referral treatment for severe malaria has not been fully explored, but it remains a promising intervention In pregnancy, quinine continues to play a critical role in the management of malaria, especially in the first trimester, and it will remain a mainstay of treatment until safer alternatives become available For uncomplicated malaria, artemisinin-based combination therapy (ACT) offers a better option than quinine though the difficulty of maintaining a steady supply of ACT in resource-limited settings renders the rapid withdrawal of quinine for uncomplicated malaria cases risky The best approach would be to identify solutions to ACT stock-outs, maintain quinine in case of ACT stock-outs, and evaluate strategies for improving quinine treatment outcomes by combining it with antibiotics In HIV and TB infected populations, concerns about potential interactions between quinine and antiretroviral and anti-tuberculosis drugs exist, and these will need further research and pharmacovigilance
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TL;DR: The palladium-catalyzed coupling of amines with aryl halides or aryls alcohol derivatives, commonly dubbed Buchwald-Hartwig amination, has matured from a synthetic laboratory procedure to a technique that is widely used in natural product synthesis as well as in other fields of academic interest.
Abstract: The palladium-catalyzed coupling of amines with aryl halides or aryl alcohol derivatives, commonly dubbed Buchwald–Hartwig amination, has matured from a synthetic laboratory procedure to a technique that is widely used in natural product synthesis as well as in other fields of academic interest. Furthermore, due to the versatility and reliability of this reaction, researchers in industrial environments have included this methodology in their toolbox as a standard procedure for the synthesis of amine derivatives. Therefore, it is not surprising that first industrial processes up to ton-scale have been performed using this cross-coupling reaction. The authors who are involved in the application of this reaction to industrial processes on this scale give an overview of the recent developments in this field of chemistry, also including fundamental principles, with a special focus on the industrial approach and issues to be considered relevant in scaling-up this transition metal-catalyzed chemistry. This review differs from the already existing excellent academic reviews by focusing on the practical problems arising during implementing the methodology in an industrial environment as well as giving practical hints to this end.
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TL;DR: A number of 7-substituted quinolone derivatives were synthesized and evaluated for antibacterial and cytotoxic activities and preliminary results indicated that most compounds tested demonstrated better activity against methicillin-resistant Staphylococcus aureus than norfloxacin.
Abstract: A number of 7-substituted quinolone derivatives were synthesized and evaluated for antibacterial and cytotoxic activities. Preliminary results indicated that most compounds tested in this study demonstrated better activity against methicillin-resistant Staphylococcus aureus than norfloxacin. Among them, 1-(4-amino-2-fluorophenyl)-6-fluoro-1,4-dihydro-7-[4-[2-(4-methoxyphenyl)-2-hydroxyiminoethyl]-1-piperazinyl]-4-oxo-3-quinolinecarboxylic acid (11d) and its ketone precursor 10d exhibited significant activities against Klebsiella pneumoniae, methicillin-resistant S. aureus, erythromycin- and ampicillin-resistant Streptococcus pneumoniae, and vancomycin-resistant Enterococcus faecalis. Due to strong cytotoxicities of 11d (a mean log GI(50) of -5.40), compound 10d, with good antibacterial activities and low cytotoxicities (a mean log GI(50) of -4.67), is a more potential drug candidate.
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