Rajni Kant

Cross-dehydrogenative coupling of azoles with α-C(sp3)-H of ethers and thioethers under metal-free conditions: functionalization of H-N azoles via C-H activation.

A metal-free cross-dehydrogenative coupling method for the synthesis of N-substituted azoles has been developed. The TBAI/TBHP system catalyzed the coupling of azoles with ethers and thioethers via α-C(sp(3))-H activation. Under the optimized conditions, a diverse range of un/substituted azoles such as 1H-benzimidazole, 9H-purine, 1H-benzotriazole, 1H-1,2,3-triazole, 1H-1,2,4-triazole, and 1H-pyrazole were successfully employed for coupling with various ethers and thioethers such as tetrahydrofuran, tetrahydropyran, 1,4-dioxane, diethyl ether, tetrahydrothiophene, and 1,3-dithiolane.

An efficient one-pot synthesis, structure, antimicrobial and antioxidant investigations of some novel quinolyldibenzo[b,e][1,4]diazepinones

A highly improved one-pot procedure for the synthesis of diazepinones, which incorporate a bioactive quinoline nucleus, under catalyst-, and solvent-free environment has been developed. The method allowed us to achieve the products in high yields without requiring a chromatographic separation. All new quinolyldibenzo[b,e][1,4]diazepinones 6a-h thus obtained were further treated to achieve N10-allylated products 7a-h by a simple allylation. The structure of all new synthesized compounds was established based on elemental analysis, mass, (1)H NMR, (13)C NMR, IR spectral data, 2D NMR experiments, and single crystal X-ray study. From in vitro antimicrobial activity studies it revealed all are active against Gram positive (Streptococcus pneumoniae, Clostridium tetani, and Bacillus subtilis), Gram negative (Salmonella typhi, Vibrio chlolerae and Escherichia coli), M. Tuberculosis H37RV bacteria, and fungus like Candia albicans and Aspergillus fumigatus. All were also found to display good antioxidant activity of a ferric reducing power.

Tubulin inhibitors from an endophytic fungus isolated from Cedrus deodara.

From an endophytic fungus, a close relative of Talaromyces sp., found in association with Cedrus deodara, four compounds including two new ones (2 and 4) were isolated and characterized. The structures of two compounds (1 and 4) were confirmed by X-ray crystallography. The compounds displayed a range of cytotoxicities against human cancer cell lines (HCT-116, A-549, HEP-1, THP-1, and PC-3). All the compounds were found to induce apoptosis in HL-60 cells, as evidenced by fluorescence and scanning electron microscopy studies. Also, the compounds caused significant microtubule inhibition in HL-60 cells.

Novel Brønsted Acidic Ionic Liquid ([CMIM][CF3COO]) Prompted Multicomponent Hantzsch Reaction for the Eco-Friendly Synthesis of Acridinediones: An Efficient and Recyclable Catalyst

AbstractsA novel, highly efficient and recyclable Brønsted acidic ionic liquid ([CMIM][CF3COO]) has been successfully implemented for the synthesis of acridinediones in aqueous media. Recyclability of novel catalyst, high yields, use of environmentally benign aqueous media as solvent, simple product isolation, high atom economy and sidestep to column chromatography are the noteworthy features of this protocol. This protocol is competent for producing wide library of acridinediones in good to excellent yields. Furthermore, molecular structure and relative stereochemistry of 4c and 4s derivatives were confirmed by single-crystal X-ray diffraction.Graphical Abstract

Enantioselective Synthesis of N-PMP-1,2-dihydropyridines via Formal [4 + 2] Cycloaddition between Aqueous Glutaraldehyde and Imines.

A simple and highly practical one-pot formal [4 + 2] cycloaddition approach for the enantioselective synthesis of N-PMP-1,2-dihydropyridines (DHPs) is described. This chemistry involves an amino-catalytic direct Mannich reaction/cyclization followed by IBX-mediated chemo- and regioselective oxidation sequence between readily available aqueous glutaraldehyde and imines under very mild conditions. A series of N-PMP-1,2-DHPs have been prepared in high yields and excellent enantioselectivity. This method also gives access to both enantiomers of 1,2-DHPs in surplus amount by shifting the catalyst configuration.

Disubstituted diphenyldithiophosphates of cadmium: synthesis, characterization, and single-crystal X-ray structure

A series of new disubstituted diphenyldithiophosphate complexes of cadmium [{(ArO)2PS2}2Cd] (9–12) have been isolated in aqueous media while their donor stabilized adducts [{(ArO)2PS2}2Cd·2C5H5N] (13–16) [(Ar = 2,4-(CH3)2C6H3, 2,5-(CH3)2C6H3, 3,4-(CH3)2C6H3 and 3,5-(CH3)2C6H3)] have been isolated in chloroform. These newly synthesized complexes were characterized by elemental analyses, IR and NMR (1H, 13C and 31P) spectroscopic analyses. The dithiophosphate ligands are coordinated bidentate to the cadmium ion via the two thiolate sulfurs. The compounds [{(3,5-CH3)2C6H3O}2PS2HNEt3] (4) and [{(3,5-CH3)2C6H3O}2PS2]2Cd(NC5H5)2 (16) crystallize in the monoclinic system with space group P21/c. Single-crystal X-ray analysis of 4 reveals that phosphorus of the anion is tetrahedrally bonded to two S and two O atoms. The structure is stabilized by cation–anion N–H⋯S intermolecular hydrogen bond interactions. In 16, two diphenyldithiophosphate ions are bidentate with both sulfurs coordinated to cadmium. Each forms a four-membered chelate ring in the equatorial plane. Two pyridines are axially coordinated to cadmium leading to octahedral geometry. The thermal properties of this complex have also been examined by combined DTA/DTG thermal analyses. Graphical Abstract

One-pot synthesis of 1,4-disubstituted 1,2,3-triazoles via Huisgen 1,3-dipolar cycloaddition catalysed by SiO2–Cu(I) oxide and single crystal X-ray analysis of 1-benzyl-4-phenyl-1H-1,2,3-triazole

A one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles via Huisgen 1,3-dipolar cycloaddition reaction between terminal alkynes, benzyl/allyl/alkyl halides, and NaN3 in water at room temperature using silica-supported copper(I) oxide (SiO2–Cu2O) has been developed. Various supported copper(I) oxide catalysts have been tested for this reaction where silica-supported copper(I) oxide works well in this reaction. The catalyst being heterogeneous can be easily recovered at the end of reaction and can be reused making the process completely economical. A single crystal X-ray analysis of 1-benzyl-4-phenyl-1H-1,2,3-triazole has revealed that the compound crystallizes in the monoclinic space group P21.Graphical abstract.

Efficient synthesis of some new antiproliferative N-fused indoles and isoquinolines via 1,3-dipolar cycloaddition reaction in an ionic liquid

Syntheses of some new pyrrolo-fused pyrrolo[1,2-a] indole derivatives have been achieved by combining N-allyl-indole-2-carbaldehyde with a variety of N-alkyl-glycine esters as well as tetrahydroisoquinolines in an ionic liquid, triethylammonium acetate (TEAA), a recyclable reaction medium, via intramolecular [3+2] cycloaddition reaction. This new method is highly efficient, and the ionic liquid employed is recyclable. The stereochemistry of all the compounds was confirmed by 2D NMR NOESY and in some cases single crystal X-ray diffraction data. The in vitro screening of all new candidates against various bacterial strains and representative human solid tumor cell lines, A549 (lung), HeLa (cervix), SW1573 (lung), T-47D (breast) and WiDr (colon), revealed that many of them have good antibacterial, antifungal and antitubercular and antiproliferative activities.

Triethylammonium acetate-mediated domino-Knoevenagel-hetero-Diels–Alder reaction: synthesis of some angular polyheterocycles

A solvent-cum catalyst, ionic liquid triethylammonium acetate-mediated one-pot procedure for the synthesis of some new angular benzopyrano[3,4-c]pyrano-fused pyrazoles, all of which incorporate a tertiary ring junction carbon, has been developed. The stereochemistry of the products has been confirmed by single-crystal X-ray diffraction data.Graphical abstract

An improved microwave assisted one-pot synthesis, and biological investigations of some novel aryldiazenyl chromeno fused pyrrolidines

An improved microwave assisted one-pot method for the synthesis of twelve new aryldiazenylchromeno [4,3-b] pyrrolidines via intramolecular azomethine ylide cycloaddition route is described. The method is efficient and advantageous over conventional and solvent-free thermal methods. The stereochemistry of the compounds was confirmed on the basis of various NMR experiments, and finally by single crystal X-ray diffraction data. N-Methyl or ethyl pyrrolidine based heterocycles gave good biological activities.