Browsing by Author "Kumar, Anil"

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1-Butyl-3-methylimidazolium p-toluenesulfinate: a novel reagent for synthesis of sulfones and β-ketosulfones in ionic liquid
(Elsiever, 2011-10-12) Kumar, Anil
A novel task-specific ionic liquid, 1-butyl-3-methylimidazolium p-toluenesulfinate, [bmim][p-TolSO2] has been synthesized and used as a nucleophile for the reaction with alkyl bromides and phenacyl bromides to prepare sulfones and β-ketosulfones in excellent yields (80–93%) in [bmim][BF4] ionic liquid. The isolated yields of sulfones and β-ketosulfones were higher in [bmim][BF4] than other organic solvents at room temperature.
1-Methyl-3-butylimidazolium Decatungstate in Ionic Liquid: An Efficient Catalyst for the Oxidation of Alcohols
(Thieme, 2005) Kumar, Anil
An excellent system for the selective oxidation of benzylic and secondary alcohols with hydrogen peroxide catalyzed by 1-methyl-3-butylimidazolium decatungstate in [bmim][BF4] ionic liquid is described. The catalytic system is reusable and products are obtained in excellent yield under environmentally benign conditions.
2-(3'-Indolyl)-N-arylthiazole-4-carboxamides: Synthesis and evaluation of antibacterial and anticancer activities
(Elsiever, 2015-10) Kumar, Dalip; Kumar, Anil
A new series of 2-(3′-indolyl)-N-arylthiazole-4-carboxamides 17a–p has been designed and synthesized. Initial reaction of readily available thioamides 15 with bromopyruvic acid under refluxing conditions produced different thiazole carboxylic acids 16 which upon coupling with arylamines by using EDCI·HCl and HOBt afforded diverse arylthiazole-4-carboxamides 17a–p in 78–87% yields. Antibacterial activity evaluation against Gram-positive and Gram-negative bacterial strains led to compounds 17i–k and 17o as potent and selectively (Gram-negative) antibacterial agents. The cytotoxicity of thiazole carboxamides 17a–p was also evaluated on a panel of human cancer cell lines. Among the tested derivatives, compounds 17i (IC50 = 8.64 μM; HEK293T) and 17l (IC50 = 3.41 μM; HeLa) were identified as the most potent analogues of the series. Preliminary mechanism of action studies of thiazole carboxamide 17i suggested that its cytotoxicity against HeLa cells involves the induction of cell death by apoptosis.
3-substitued indoles: one-pot synthesis and evaluation of anticancer and Src kinase inhibitory activities
(Elsiever, 2011-06-15) Kumar, Anil
An efficient and economical method was developed for the synthesis of 3-substituted indoles by one-pot three-component coupling reaction of a substituted or unsubstituted benzaldehyde, N-methylaniline, and indole or N-methylindole using Yb(OTf)3–SiO2 as a catalyst. All the synthesized compounds were evaluated for inhibition of cell proliferation of human colon carcinoma (HT-29), human ovarian adenocarcinoma (SK-OV-3), and c-Src kinase activity. The 4-methylphenyl (4o and 4p) and 4-methoxyphenyl (4q) indole derivatives inhibited the cell proliferation of SK-OV-3 and HT-29 cells by 70–77% at a concentration of 50 μM. The unsubstituted phenyl (4d) and 3-nitrophenyl (4l) derivatives showed the inhibition of c-Src kinase with IC50 values of 50.6 and 58.3 μM, respectively.
Advances in Functionalized Ionic Liquids as Reagents and Scavengers in Organic Synthesis
(Bentham Science, 2014) Kumar, Anil
Functionalized ionic liquids (FILs) synthesized with specific desired chemical properties have shown promising results in various areas of organic synthesis. In supported organic synthesis, FILs have become known as a new alternative to commonly used PEG and fluorous soluble supports. This review summarizes the progress of recent development in the synthesis of functionalized ionic liquids with emphasis on their applications as reagents and scavengers in organic synthesis.
Advances in transition metal‐catalyzed C(sp2)–H bond functionalization using allyl alcohols
(Wiley, 2025-03) Kumar, Anil
The transition metal-catalyzed directed site-selective C─H bond functionalization utilizing allyl alcohols as coupling partner has been an intriguing area of research and has made considerable advances during the past decade. Multifunctional coupling characteristics of the allyl alcohol in the regioselective C(sp2)–H functionalization using transition metal-catalysis produces alkyl, alkenyl, allyl, and annulated products. These reactions provide an effective synthetic tool to afford diverse functionalized scaffolds that are of interest in synthetic and medicinal sciences. This review covers the developments of directed site-selective C(sp2)–H functionalization with unactivated allyl alcohols as the coupling partner using the transition metal-catalysis till December, 2024.
Au-Catalyzed Synthesis of Thiopyrano[2,3-b]indoles Featuring Tandem Rearrangement and Hydroarylation
(ACS, 2017) Kumar, Anil; Kumar, Dalip
Gold(III)-catalyzed synthesis of 14-π electron heteroaromatic thiopyrano[2,3-b]indole is reported using conjugated enyne tethered indole sulfides, featuring skeletal rearrangement conjoined with intramolecular hydroarylation (via C3–H functionalization of the indole core) and oxidative aromatization. Subsequent Pd-catalyzed C–C coupling resulted in a 16-π electron heteroaromatic isothiochromeno[1,8,7-bcd]indole.
Ball-Milling-Enabled Zn(OTf)2-Catalyzed Friedel–Crafts Hydroxyalkylation of Imidazo[1,2-a]pyridines and Indoles
(ACS, 2023-02) Kumar, Anil
A facile and efficient synthetic method for the construction of C3-hydroxyalkylated imidazo[1,2-a]pyridines and indoles by a Zn(OTf)2-catalyzed Friedel–Crafts hydroxyalkylation of imidazo[1,2-a]pyridines and indoles with carbonyl compounds under mechanochemical conditions is reported. Good product selectivity, shorter reaction time, ambient reaction temperature, tolerance of a wide range of functional groups, broad substrate scope, moderate to good yield of products, and scalability are the salient features of the developed methodology.
Biochemistry and genetics of ACC deaminase: a weapon to “stress ethylene” produced in plants
(Frontiers, 2015-09) Jha, Prabhat N.; Kumar, Anil
1-aminocyclopropane-1-carboxylate deaminase (ACCD), a pyridoxal phosphate-dependent enzyme, is widespread in diverse bacterial and fungal species. Owing to ACCD activity, certain plant associated bacteria help plant to grow under biotic and abiotic stresses by decreasing the level of “stress ethylene” which is inhibitory to plant growth. ACCD breaks down ACC, an immediate precursor of ethylene, to ammonia and α-ketobutyrate, which can be further metabolized by bacteria for their growth. ACC deaminase is an inducible enzyme whose synthesis is induced in the presence of its substrate ACC. This enzyme encoded by gene AcdS is under tight regulation and regulated differentially under different environmental conditions. Regulatory elements of gene AcdS are comprised of the regulatory gene encoding LRP protein and other regulatory elements which are activated differentially under aerobic and anaerobic conditions. The role of some additional regulatory genes such as AcdB or LysR may also be required for expression of AcdS. Phylogenetic analysis of AcdS has revealed that distribution of this gene among different bacteria might have resulted from vertical gene transfer with occasional horizontal gene transfer (HGT). Application of bacterial AcdS gene has been extended by developing transgenic plants with ACCD gene which showed increased tolerance to biotic and abiotic stresses in plants. Moreover, distribution of ACCD gene or its homolog's in a wide range of species belonging to all three domains indicate an alternative role of ACCD in the physiology of an organism. Therefore, this review is an attempt to explore current knowledge of bacterial ACC deaminase mediated physiological effects in plants, mode of enzyme action, genetics, distribution among different species, ecological role of ACCD and, future research avenues to develop transgenic plants expressing foreign AcdS gene to cope with biotic and abiotic stressors. Systemic identification of regulatory circuits would be highly valuable to express the gene under diverse environmental conditions.
Biomimetic Oxidation of Curcumin with Hydrogen Peroxide Catalyzed by 5,10,15,20-Tetraarylporphyrinatoiron(III) Chlorides in Dichloromethane
(J-Stage, 2003) Kumar, Anil
The biomimetic oxidation of curcumin, a main turmeric pigment with hydrogen peroxide catalyzed by different 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl] in dichloromethane has been studied to give a C–C coupled curcumin dimer in 40—70% yield. The structure of the dimer has been elucidated by 1H-, 13C-NMR, IR and FAB-Mass spectroscopic data.
Biomimetic Oxidation of Veratryl Alcohol with H2O2 Catalyzed by Iron(III) Porphyrins and Horseradish Peroxidase in Ionic Liquid
(Thieme, 2007) Kumar, Anil
3,4-Dimethoxybenzyl alcohol (veratryl alcohol) is a model compound for lignin substructures and its oxidation with H2O2 catalyzed by iron(III) porphyrins and horseradish peroxidase (HRP) in ionic liquids has been described. Veratraldehyde and 2-hydroxymethyl-5-methoxy-2,5-cyclohexadiene-1,4-dione were the two major products of the oxidation of veratryl alcohol at room temperature. The iron(III) porphyrin or HRP immobilized in ionic liquids showed increased catalytic activity and can be recycled and this is believed due to the stabilization of highvalent oxoiron(IV) π-cation radical intermediate generated in the reaction.
Biomimetic Reduction of Nimesulide with NaBH4 Catalyzed by Metalloporphyrins
(J-Stage, 2002) Kumar, Anil
The biomimetic reduction of anti-inflammatory drug, nimesulide (1) with sodium borohydride catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl] has been studied in organic solvents under anaerobic and aerobic conditions.
Bismuth triflate-catalyzed condensation of indoles with acetone
(RSC, 2013) Kumar, Anil
Reaction of different substituted indoles with acetone was investigated using Bi(OTf)3 as a catalyst. An efficient protocol was developed for the synthesis of spiro indoles, 1-methyl-cyclopenta[b]indole and bis(1-methyl-1H-indolyl)propanes via the reaction of indole with acetone in the presence of Bi(OTf)3. The reaction conditions were benign, required shorter reaction time, and gave good yields.
Bulky Selenium Ligand Stabilized Trans-Palladium Dichloride Complexes as Catalyst for Silver-Free Decarboxylative Coupling of Coumarin-3-Carboxylic Acids
(Wiley, 2021-12) Kumar, Anil
This report describes the syntheses of three new trans-palladium dichloride complexes of bulky selenium ligands. These complexes possess a Cl−Pd−Cl rotor spoke attached to a Se−Pd−Se axle. The new ligands and palladium complexes (C1−C3) were characterized with the help of NMR, HRMS, UV-Vis., IR, and elemental analysis. The single-crystal structure of metal complex C2 confirmed a square planar geometry of complex with trans-orientation. The X-ray structure revealed intramolecular secondary interactions (SeCH—Cl) between chlorine of PdCl2 and CH2 proton of selenium ligand. Variable-temperature NMR data shows coalescence of diastereotopic protons, which indicates pyramidal inversion of selenium atom at elevated temperature. The relaxed potential energy scan of C2 suggests a rotational barrier of ∼12.5 kcal/mol for rotation of chlorine atom through Cl−Pd−Cl rotor. The complex C3 possesses dual intramolecular secondary interactions (OCH2—Cl and SeCH2—Cl) with stator ligand. Molecular rotor C2 was found to be a most efficient catalyst for the decarboxylative Heck-coupling under mild reaction conditions. The protocol is applicable to a broad range of substrates with large functional group tolerance and low catalyst loading (2.5 mol %). The mechanism of decarboxylative Heck-coupling reaction was investigated through experimental and computational studies. Importantly the reaction works under silver-free conditions which reduces the cost of overall protocol. Further, the catalyst also worked for decarboxylative arylation and decarboxylative Suzuki-Miyaura coupling reactions with good yields of the coupled products.
C--H Functionalization of Indazoles
(Wiley, 2022-11) Kumar, Anil; Sakhuja, Rajeev
The indazole is an important class of bicyclic nitrogen-containing heterocycle that forms the core structure of a large number of compounds with potential therapeutic value. Consequently, CH functionalization of this scaffold has been extensively explored using transition metal-catalyzed and metal-free CH functionalization strategies. This article provides a perspective on various strategies that have been developed to add a substituent on this heterocycle core and their appropriate coupling partners.
Carbocyclodipeptides as Modified Nucleosides: Synthesis and Anti- HIV Activities
(CSP, 2014) Kumar, Anil
A new class of nucleoside analogues were synthesized using cyclic dipeptides and modified 2′-deoxyfuranoribose sugars to introduce flexibility by peptides in place of common nucleoside bases and to determine their biological properties. The synthesis was carried out by coupling of a protected ribose sugar with synthesized dipeptides in the presence of hexamethyldisilazane and trimethylsilyltriflate. The final products were characterized by NMR and high-resolution MS-TOF spectroscopy. The compounds were evaluated for anti-HIV activities. 1-(4-Azido-5-(hydroxymethyl)tetrahydrofuran-2-yl)-3,6-diisopropylpiperazine-2,5-dione (compound 14) containing 3- and 6-isopropyl groups in the base and 3′-azide (EC50 = 1.96 μmol/L) was the most potent compound among all of the synthesized analogs.
Catalyst-Controlled Regiodivergent Oxidative Annulation of 2-Arylimidazo[1,2-a]pyridines with Cinnamaldehyde Derivatives for Construction of Fused N-Heterocyclic Framework
(ACS, 2023-09) Kumar, Anil
Catalyst-dependent regioselective oxidative annulation of 2-arylimidazo[1,2-a]pyridines with cinnamaldehyde derivatives to construct fused N-heterocyclic frameworks has been described. The annulation reaction afforded 5-arylnaphtho[1′,2′:4,5]imidazo[1,2-a]pyridine-6-carbaldehydes in the presence of [RhCp*Cl2]2 as catalyst while 1,7-diarylimidazo[5,1,2-cd]indolizine-6-carbaldehydes were obtained using Pd(OAc)2 as catalyst. The reaction produced annulated products in good yields and exhibited broad substrate scope and excellent functional group tolerance. The method provides two different isomeric annulated products bearing an aldehyde functionality which can be elaborated into an array of functionalities leading to valuable compounds.
Cerium Triflate: An Efficient and Recyclable Catalyst for Chemoselective Thioacetalization of Carbonyl Compounds under Solvent-Free Conditions
(CSIRO, 2009-08-26) Kumar, Anil
A simple and efficient chemoselective thioacetalization of carbonyl compounds has been achieved using Ce(OTf)3 (10 mol-%) as a catalyst under solvent-free conditions. Advantages of the methodology include very short reaction times, excellent yields, the catalytic use of a water tolerant Lewis acid, and simple recovery and reuse of the catalyst.
Chemical and biochemical transformations in ionic liquids
(Elsiever, 2005-01) Kumar, Anil
The synthesis of ionic liquids and their applications in various chemical and biochemical transformations, in ecofriendly-milder conditions have been reviewed. Metal and enzyme catalyzed as well as non-catalyzed reactions in ionic liquids have been covered with 354 refs.
ChemInform Abstract: An Efficient and Simple One-Pot Synthesis of β-Acetamido Ketones Catalyzed by Ytterbium Triflate in Ionic Liquid
(Wiley, 2009-09) Khungar, Bharti; Kumar, Anil
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.