Department Of Chemistry

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Author: search.filters.author.Singh, VirenderStart date: 2012

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Now showing 1 - 10 of 27
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    From 2011 to 2022: The development of pyrazole derivatives through the ?,?-unsaturated carbonyl compounds
    (HeteroCorporation, 2023-11-25T00:00:00) Sharma, Shubham; Singh, Virender; Vaishali; Kumar, Rakesh; Jamra, Rahul; Banyal, Naveen; Jyoti
    The synthesis of pyrazole derivative using ?,?-unsaturated carbonyl compounds has attracted increasing attention of the synthetic organic chemist community. Interestingly, the simplicity of the synthetic method, high reactivity, and ease of incorporating diversity into the desired prototype have contributed a lot toward the exploration of ?,?-unsaturated carbonyl compounds by various research groups. Due to the tremendous pharmacological significance of pyrazole derivatives, their synthesis has been one of the leading research frontiers in recent years. As prime examples, sildenafil, zometapin, Celebrex, and rimonabant have been successfully commercialized in the market to treat various life-challenging diseases. Considering the great profile of ?,?-unsaturated carbonyl compound in the synthesis of biologically active pyrazole derivatives, this review incorporates contemporary literature (2011�2022) on the synthesis of pyrazole and its derivatives using ?,?-unsaturated carbonyl compound as a starting precursor. � 2023 Wiley Periodicals LLC.
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    Synthesis and Characterization of Novel Pd@rGO?CuFe2O4 Magnetic Nanoparticles: A Recyclable Catalyst for C?C Coupling Reaction in Biomass-Derived Organic Solvent
    (John Wiley and Sons Inc, 2023-10-06T00:00:00) Teli, Yaqoob A.; Reetu, Reetu; Singh, Priyanka Gurdev; Patel, Mayur Jagdishbhai; Dash, Sonali; Paine, Snehangshu; Prabhakar, Poornachandra Shamanna; Singh, Virender; Keremane, Kavya S.; Al-Zaqri, Nabil; Mukherjee, Kalisadhan; Dutta, Saikat; Malakar, Chandi C.
    Development of new, cost effective, stable heterogeneous catalyst for the organic transformations is an important thematic area of research. Present work describes the development of new Pd@rGO?CuFe2O4 catalyst and demonstrates its effectiveness for Suzuki-Miyaura type coupling reactions. The additional advantage of this reaction is its feasibility using biomass-derived solvent like ?-Valerolactone (GVL) in aqueous media. The catalyst is prepared hydrothermally and characterized using XRD, FESEM, EDX, and XPS analysis. The catalyst exhibits excellent activity and recyclability (up to six times) in the C?C coupling reaction to deliver the corresponding biaryl molecules in yields up to 90 %. High efficiency for the conversion of nitriles to amides is also revealed by the prepared catalyst. � 2023 Wiley-VCH GmbH.
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    Metal- and Hazardous Reagent-Free Transamidation Process: the NH2OH?HCl Promoted N-Formylation and N-Acylation Reaction under Solvent-Less Conditions
    (Taylor and Francis Ltd., 2023-09-14T00:00:00) Devi, Elangbam Pinky; Kant, Kamal; Kaldhi, Dhananjaya; Ghanta, Susanta; Sengupta, Ragini; Al-Zaqri, Nabil; Singh, Virender; Malakar, Chandi C.
    An efficient transamidation process has been described under solvent-less conditions. The transformation has been accomplished by employing NH2OH?HCl as a reagent and amines as substrates. The developed method is achieved in the absence of metals and hazardous reagents. A series of amines were explored to obtain the N-formylation and N-acylation reactions with excellent yields (81-96%) of products. The DFT analysis was also performed, which provides a clear understanding of the described N-formylation process. The postulated mechanism is well supported by the control experiments. � 2023 Taylor & Francis Group, LLC.
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    Transition-Metal-Free Cascade C-N Bond Formation: An Effective Strategy for the Synthesis of ?-Carboline N-Fused Imidazolium Acetates and Estimation of their Light-Emitting Properties
    (Georg Thieme Verlag, 2023-08-08T00:00:00) Singh, Manpreet; Vaishali, Vaishali; Deepika, Deepika; Jyoti, Jyoti; Sharma, Shubham; Banyal, Naveen; Kumar, Prashant; Budhalakoti, Bharti; Malakar, Chandi C.; Singh, Virender
    A simple, efficient, and practical metal-free protocol has been devised to synthesize imidazopyrido[3,4-b]indole-based fluorophores decorated with carbazole/ F-carboline/pyridine scaffolds via three consecutive C.N bond formations in a single operation. A wide range of aromatic amines (2-aminopyridines, 3-aminocarbazole, and anilines) were successfully applied to synthesize the complex imidazolium ions. The significant features of this strategy include high efficiency, mild and environmentally benign reaction conditions, no chromatographic purification, and broad substrate scope with excellent yields of the isolated products. Moreover, excellent photophysical properties (up to 85%) were exhibited by these fluorophores. � 2022 Georg Thieme Verlag. All rights reserved.
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    DABCO Mediated Sulfur Activation-Intramolecular De-Nitration Strategy for the Synthesis of Novel Dihydrothiochromeno[4,3-c]pyrazoles
    (John Wiley and Sons Inc, 2023-07-24T00:00:00) Deepika; Paul, Avijit K.; Malakar, Chandi C.; Bansal, Ajay; Singh, Virender
    A facile and highly efficient metal-free approach has been unfolded for the synthesis of novel dihydrothiochromeno[4,3-c]pyrazoles using elemental sulfur as a powerful sulfurating reagent. This method includes sp2 C?H functionalization followed by sp2 C?NO2 group displacement using elemental sulfur as an odourless sulfur source activated by DABCO in DMSO. Using the developed synthetic strategy, a library of 29 novel dihydrothiochromeno[4,3-c]pyrazoles, incorporating two pharmacologically important scaffolds has been synthesized in 52�76% yield with a broad substrate scope. A sensible mechanistic proposal has been projected based on control experiments. � 2023 Wiley-VCH GmbH.
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    Copper catalysed regioselective synthesis of pyrimidine substituted Indolizino[8,7-b]indole derivatives via cascade A3 annulation
    (Elsevier Ltd, 2023-07-08T00:00:00) Kumar, Sunit; Kumar, Rakesh; Malakar, Chandi C.; Singh, Virender
    Cu(II) salt has been found to be an efficient catalyst for the regioselective synthesis of a series of novel indolizino [8,7-b]indole derivatives with pyrimidine tethers via three-component annulation of 1-formyl-9H-?-carbolines (Kumujian C), 2-amino-pyrimidines and terminal alkynes. The reactions proceeds through Cu-catalysed A3-coupling followed by intramolecular cyclisation in a cascade manner. The scope of strategy has been exemplified with a library of biologically interesting 25 indolizino [8,7-b]indoles with pyrimidine tethers which mimics several natural products. � 2023 Elsevier Ltd
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    Copper-Catalyzed C(sp3)? Functionalization and Annulation of 2-Bromoaryl Oximes with Active Methylene Compounds towards Synthesis of Isoquinoline N-Oxides
    (John Wiley and Sons Inc, 2023-06-09T00:00:00) Patel, Chandresh K.; Gujjarappa, Raghuram; Kant, Kamal; Ghanta, Susanta; Singh, Virender; Kabi, Arup K.; Al-Zaqri, Nabil; Malakar, Chandi C.
    The established process proceeds through copper (II)-catalyzed C(sp3)? functionalization of ?-diketones/?-ketoesters with 2-bromobenzaldehyde oximes followed by the intramolecular cyclization of in situ generated acylated intermediates to deliver isoquinoline N-oxides. The copper(II) acetate catalyzed C?H functionalization showed maximum efficacy at 60 �C in methanol/toluene as solvent. The described reaction conditions were applicable over a wide range of substrates with a variety of functional groups to yield isoquinoline N-oxides in yields up to 85%. The developed approach was further elucidated by means of control experiments and DFT calculations. � 2023 Wiley-VCH GmbH.
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    An efficient metal-free and catalyst-free C�S/C�O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides
    (Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2023-03-02T00:00:00) Sharma, Shubham; Singh, Dharmender; Kumar, Sunit; Vaishali; Jamra, Rahul; Banyal, Naveen; Deepika; Malakar, Chandi C.; Singh, Virender
    An operationally simple and metal-free approach is described for the synthesis of pyrazole-tethered thioamide and amide conjugates. The thioamides were generated by employing a three-component reaction of diverse pyrazole C-3/4/5 carbaldehydes, secondary amines, and elemental sulfur in a single synthetic operation. The advantages of this developed protocol refer to the broad substrate scope, metal-free and easy to perform reaction conditions. Moreover, the pyrazole C-3/5-linked amide conjugates were also synthesized via an oxidative amination of pyrazole carbaldehydes and 2-aminopyridines using hydrogen peroxide as an oxidant. � 2023 Sharma et al.
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    A Catalyst- and Metal-free Approach towards the Synthesis of ?-Carboline tethered Imidazole Derivatives and Assessment of their Photophysical Properties
    (John Wiley and Sons Inc, 2023-04-25T00:00:00) Vaishali; Singh, Virender
    A simple, facile, and highly efficient approach has been unfolded for the syntheses of ?-carboline tethered imidazole derivatives. This expeditious catalyst-free strategy proceeds through the assembly of 1-formyl-9H-?-carbolines, glyoxal derivatives and ammonium acetate via the formation of concomitant four C?N bonds in a one-pot operation. The current approach has various advantages, including multicomponent nature, simple reaction conditions, short reaction time, broad substrate scope, and high product yield. Importantly, the ?-carboline tethered imidazole derivatives displayed excellent photophysical properties with quantum yield up to 90%. � 2023 Wiley-VCH GmbH.
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    Potassium tert-Butoxide-Mediated Synthesis of 2-Aminoquinolines from Alkylnitriles and 2-Aminobenzaldehyde Derivatives
    (John Wiley and Sons Inc, 2022-12-08T00:00:00) Kishore, Pendyala Satya; Gujjarappa, Raghuram; Putta, V. P. Rama Kishore; Polina, Saibabu; Singh, Virender; Malakar, Chandi C.; Pujar, Prasad Pralhad
    KOtBu mediates the reaction between 2-amino arylcarbaldehydes and benzyl/alkyl cyanides toward the expeditious formation of 2-aminoquinolines under transition-metal-free conditions. The described transformation proceeds through in-situ generated enimine intermediate from benzyl/alkyl cyanides under KOtBu-mediated reaction conditions. The substituted 2-aminoquinolines were realized in excellent yields at room temperature and shorter reaction time. The designed process exhibits operational simplicity and broad functional group tolerance in delivering the products of high significance. � 2022 Wiley-VCH GmbH.