Now showing 1 - 5 of 5
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    Enantioselective Synthesis of 3-Amino-3’-carbazole Oxindole Derivatives via Friedel-Crafts Aminoalkylation Reaction
    (18-02-2022)
    Muthusamy, Subramaniam
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    Kumarswamyreddy, Nandarapu
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    Organocatalytic Friedel-Crafts aminoalkylation reaction is demonstrated in this study for the construction of biologically important hybrid molecular architectures of carbazole containing 3-amino oxindoles using bifunctional cinchonidine derived thiourea organocatalyst. The Friedel-Crafts functionalization of 4-hydroxy carbazole with isatin derived ketimines well performed with a wide range of substrates resulted in excellent yields (up to 95 %) and enantioselectivities (up to 99 % ee) of the desired products. A minimal catalyst loading (0.5 mol%) was utilized at ambient temperatures under mild reaction conditions.
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    Durable polymeric: N -halamine functionalized stainless steel surface for improved antibacterial and anti-biofilm activity
    (01-01-2021)
    Rai, Rajani Kant
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    Kanniyappan, Hemalatha
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    Jayakrishnan, Athipettah
    Bacterial adhesion and colonization on stainless steel (SSL) based surgical instruments, hospital equipment, orthopedic implants, water purification and food processing units are a major problem. Imparting rechargeable antibacterial properties to SSL offers the prospect of a reusable and clean surface. In this study, the SSL surface was functionalized with a hydantoin-based antibacterial polymer that prevents bacterial adhesion and colonization. A new hydantoin monomer with three halogen binding sites, (Z)-N-((4-(2,5-dioxoimidazolidin-4-ylidene)methyl)phenyl)methacrylamide (DMPM), was synthesized, characterized and copolymerized with a commercially available 3-(methacryloyloxy)propyltrimethoxysilane monomer to develop the antibacterial polymer. The SSL surface was treated with piranha solution and the copolymer was covalently immobilized on the surface. The modified surface was examined for its antibacterial and anti-biofilm activity. The modified surface exhibited total kill (6 log reduction) of bacteria such as S. aureus and E. coli in 10 and 12 min respectively. The anti-biofilm activity of the modified surface was evaluated using a combination of fluorescence-based metabolic activity and scanning electron microscopy imaging suggested the comprehensive damage of S. aureus and E. coli biofilm architecture. This journal is
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    Synthesis and antibacterial activity of 2-benzylidene-3-oxobutanamide derivatives against resistant pathogens
    (01-01-2023)
    Sood, Ankur
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    Antibiotic resistance evolves naturally through random mutation. Resistance to antimicrobials is an urgent public health crisis that requires coordinated global action. The ESKAPE bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are primarily responsible for the rise in resistant pathogens. There is an immediate requirement to identify a novel molecular scaffold with potent anti-microbial properties. We developed an efficient one-step synthesis of 2-benzylidene-3-oxobutanamide and its derivatives, which allowed the introduction of an α,β-unsaturated ketone moiety in the quest to identify a new molecular scaffold. Seven compounds exhibited very good antibacterial activity in vitro against WHO priority drug-resistant bacteria such as methicillin resistant Staphyloccus aureus (MRSA) and Acinetobacter baumannii-Multi drug resistant (MDR-AB). In cultured human embryonic kidney cells and hemolysis assays, the potent compounds displayed minimal toxicity. These findings suggest that these small molecules with excellent diversity have the potential to combat antibacterial resistance.
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    Enantioselective Synthesis of 3-Acetyl Coumarin Substituted 3-Hydroxy Oxindoles and Pyranocoumarin Fused Spirooxindoles
    (20-08-2021)
    Pratap Reddy Gajulapalli, V.
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    Kumarswamyreddy, Nandarapu
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    Lokesh, Kanduru
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    Enantioselective construction of bioinspired coumarin and oxindole hybrid structures always enduring challenges in organic chemistry due to the generation of asymmetric quaternary/spiro center at the C3 position of oxindole. Herein, we demonstrated a facile enantioselective synthesis of highly functionalized 3,3’-disubstituted oxindole derivatives containing 3-acetyl coumarins and pyranocoumarin fused spirooxindoles using L-proline derived bifunctional thiourea organocatalyst through Aldol reaction and Michael addition/cyclization. The L-proline derived thiourea catalyst well performed with broad substrate scope to produce desired products in very good yields (up to 95 %) and excellent enantioselectivities (up to 99 % ee).
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    Palladium-catalyzed asymmetric allylic alkylation of 3-amino-2-oxindoles: Synthesis of 3-allyl-3-amino-2-oxindoles
    (12-10-2021)
    Kumarswamyreddy, Nandarapu
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    Jayakumar, Samydurai
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    Tartrate derived bi(oxazoline) ligand with palladium (II) species catalyzed asymmetric allylic alkylation reaction to access highly valuable 3-allyl-3-amino-2-oxindoles with vicinal quaternary and tertiary stereocenters in very good yields (up to 91%) and excellent enantioselectivity (up to 98% ee) with moderate to good diastereoselectivity (up to 5:1). The synthetic utility of 3-allyl-3-amino-2-oxindole was further demonstrated to construct spiro(oxindole-3,2′-pyrrolidine) with consecutive one quaternary and three tertiary chiral centers in good stereoselectivity (dr = 8:1 and 80% ee) through metal-free intramolecular iodocyclization reaction.