Narsidas J. Parmar

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.

An efficient domino reaction in ionic liquid: synthesis and biological evaluation of some pyrano- and thiopyrano-fused heterocycles.

An improved domino/Knoevenagel-hetero-Diels-Alder reaction of two new aldehyde substrates; 7-olefinoxy-coumarin-8-carbaldehyde and 2-alkensulfanyl-quinoline-3-carbaldehyde, with pyrazolones was studied in ionic liquid triethylammonium acetate (TEAA), affording a series of pyrazolopyran annulated-pyrano-fused coumarins, and thiopyrano-fused quinolones. Besides acting as catalyst, since no additional catalyst used, the ionic liquid TEAA also promised its easy recovery. In all new polyheterocycles, the cis-fusion of two pyranyl rings had been inferred from 2D NMR COSY and NOESY experiments. All are good antitubercular agents, as they are found active against Mycobacterium tuberculosis H37Rv, and antibacterial agents, as they are found active against three Gram-positive (Streptococcus pneumoniae, Clostridium tetani, Bacillus subtilis) and three Gram-negative (Salmonella typhi, Vibrio cholerae, Escherichia coli) bacteria.

A highly efficient, rapid one-pot synthesis of some new heteroaryl pyrano[2,3-c]pyrazoles in ionic liquid under microwave-irradiation

A highly efficient, rapid one-pot procedure has been developed for a three-component domino intermolecular Knoevenagel–intermolecular hetero-Diels–Alder reaction, to afforded indolyl- and quinolylpyrano[2,3-c]pyrazoles from corresponding heteroarylaldehyde, pyrazolone and enol ether in ionic liquid triethylammonium acetate (TEAA) under microwave (MW) irradiation. The reaction advantageously precedes in highly regio- and stereoselective manners in combination with the ease of recovering ionic liquid used in the reaction. According to literature, the heterocycles are expected to display antitubercular activity. 2D NMR NOESY (nuclear overhauser effect spectroscopy) experiments confirm the cis-orientation of the two pyran ring hydrogens; one attached to the anomeric carbon and the second to which a heteroaryl attached.

Catalyst-and solvent-free one-pot synthesis of some novel polyheterocycles from aryldiazenyl salicylaldehyde derivatives

A catalyst-and solvent-free domino/Knoevenagel-hetero-Diels–Alder (DKHDA) reaction of two aldyhyde substrates, allyl/prenyl ether tethered aryldiazenylsalicylaldehydes with corresponding pyrazolones and heterocyclic 1,3-diketones is described. Subsequent reduction of aryldiazenylpolyheterocycles, thus obtained in high yields (70–86%), afforded analogues amino frameworks with anticipated biological activity. While in a conventional procedure, no reaction was observed without activation of an allyl-based substrate, an excellent yield was achieved at higher temperature. For a prenyl based substrate, however it underwent smoothly to form a desired cyclised product. The stereochemistry of the compound was confirmed by various NMR experiments and a single crystal X-ray diffraction analysis.

Efficient One-Pot Synthesis of Precursors of Some Novel Aminochromene Annulated Heterocycles via Domino Knoevenagel–hetero-Diels–Alder Reaction

Abstract An efficient, one-pot synthetic approach to precursors of some new aminochromene/xanthene annulated heterocycles via a tetrabutylammonium hydrogen sulfate–mediated intramolecular domino Knoevenagel–hetero-Diels–Alder reaction is described. The method is general and efficient. The stereochemistry of the product was confirmed by various NMR experiments and single-crystal x-ray diffraction data. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. 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.

Chelation and extraction of copper(II) with 5-pyrazolone-based Schiff bases

Copper(II) chelates of the Schiff bases (H2L), obtained by condensation of 4-butyryl-3-methyl-1-phenyl-pyrazoline-5-one (HBMPP) with o-phenylene diamine (H2L1) and p-phenylene diamine (H2L2), have been prepared and characterized by elemental analyses, thermogravimetric analyses, magnetic measurements, diffuse reflectance spectra, IR and mass spectra, and conductance measurements. The extractability of copper(II) with H2L in chloroform was examined. Effective extraction was observed with 1 × 10−3 mol dm−3 of ligands at pH 6.5 using H2L1 and pH 7.0 using H2L2. The nature of the extracted species was ascertained by the slope analysis method. The ligand can effectively be used in solvent extraction of copper(II) from aqueous phase to organic phase.

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.

Studies on oxovanadium(IV), Cr(III), Co(II), Ni(II), and Cu(II) chelates of some bisketimino ligands

The oxovanadium(IV), Cr(III), Ni(II), Co(II), and Cu(II) chelates of some bisketimino Schiff-base ligands (H2L) obtained by condensation of 4-butyryl-3-methyl-1-phenyl-(or-1,3-diphenyl)-2-pyrazolin-5-ones with thiourea were synthesized and characterized by elemental analyses and thermogravimetric analyses, molar conductivities, magnetic susceptibility measurements, mass, infrared, and electronic spectroscopies. Ligand field parameters, such as splitting energy, Racah parameter, spin–orbit coupling constant, and covalency parameter of the Cr(III), Ni(II), and Co(II) chelates were calculated by band-fitting methods. Based on these studies, tetragonally distorted octahedral environment around OV(IV) and Cu(II) and octahedral Cr(III), Ni(II), and Co(II) have been proposed.