[Show abstract][Hide abstract] ABSTRACT: The role of ionic liquids as catalyst and solvent to mediate organic reactions is well documented. While imidazole and pyridine-based ionic liquids have traditionally been the ionic liquids of choice for organic synthesis, imidazole’s inert nature and pyridine’s toxicity is often viewed as an impediment. In the present study, we have synthesized ionic liquids (QuFs), employing non-toxic quinoline ring. The desired QuFs were readily prepared via N-alkylation and corresponding anion exchange with fluoride ions. The structures of synthesized QuFs were confirmed with advanced spectroscopic techniques such as 1H and 13C NMR, IR and mass spectrometry. The potential of these newly synthesized QuFs as catalyst for click chemistry and other reactions was explored by carrying out synthesis of 5-(p-methylphenyl)-1H-tetrazole (7), 2-dicyanomethylene-6-methyl-4,6-bis(m-methoxyphenyl)-1,2,5,6-tetrahydronicotinonitrile (12), and 3,5-dimethyl-1-(p-methoxy)-1H-pyrazole (15). Detailed thermal analysis (DSC, TGA and DTG) were carried out to study thermal stability of synthesized QuFs. Density functional theory (DFT) calculations and molecular dynamics simulations were also carried in order to establish a relation between binding energies, and structural and dynamic characteristics of QuFs.
[Show abstract][Hide abstract] ABSTRACT: In the present study, a series of dibenzoazepine triazole derivatives (24-39) were synthesized and evaluated for their in vitro bioactivities including antiglycation, antibacterial, DPPH radical scavenging, urease inhibition, antileishmanial and immunomodulatory activities. The compounds were found to be moderately active only against leishmania. Within this series, compound 26 was found to be the most active antileishaminals with IC50 value 37.4 ± 0.4 μM. Structure-activity relationships for this novel class are discussed.
Letters in Drug Design & Discovery 08/2015; 12(7). DOI:10.2174/1570180812999150225111959 · 0.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study describes the regioselective synthesis of novel 2,3,4,4a-tetrahydro-1H-carbazoles (syn-2(a-q) and anti-3(a-b)) from L-menthone via Fischer indole synthesis. The reaction between L-menthone and different substituted phenyl hydrazines, carried out in acetic acid as catalyst and solvent, yielded a mixture of corresponding 2,3,4,4a-tetrahydro-1H-carbazole diastereomers, instead of the expected indoles. These were characterized by different spectroscopic and single-crystal X-ray diffraction techniques. The isolated single diastereoisomers were further evaluated for inhibitory activities against various enzymes such as cholinesterases, xanthine oxidase, α-chymotrypsin, urease, phosphodiesterase and carbonic anhydrase-II activity, as well as against DPPH radical scavenging and anti-cancer activity against PC-3 cell line. The 2,3,4,4a-tetrahydro-1H-carbazoles show promising inhibitory activities only against acetyl- and butyrylcholinesterase. Moreover, kinetic analyses were carried out for the study of mechanism of inhibition of the active compounds.
[Show abstract][Hide abstract] ABSTRACT: The dual role of ionic liquids as catalysts and solvents in organic synthesis is well-documented. In the present study, we have synthesized novel 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)based fluorinated ILs (DBUF-ILs) simply by solvent-free quaternization and subsequent anion (F-) exchange reactions. The micellization behavior and density functional theory (DFT) calculations of DBUF-ILs have been conducted. The DFT calculations of some selected DBU derivatives provide detail information of the effect of N-substitution on the DBU as well as HOMO and LUMO energies and their corresponding band gaps are also retrieved. A click chemistry reaction for tetrazole formation is performed under solvent-free thermal and microwave irradiation. Yields obtained were in the range of 70-95%. Complete structural characterization of the each product was accomplished by several modern techniques including 1H NMR, 13C NMR, EI+ and/or FAB mass spectrometry, IR and UV spectroscopy.
[Show abstract][Hide abstract] ABSTRACT: Systemic fungal infections of humans and economically important animals are increasingly common throughout the world. These infections are severe and often hard to treat with existing safe, oral medications. Thus there has been increasing research on alternatives resulting in study of natural and synthetic inhibitors of 1,3-β-Glucan synthase (GS) and chitin synthase (CS)-enzymes important in the biosynthesis of fungal cell walls that are not utilized in human biochemistry. Some such agents have recently been introduced into parenteral clinical use. There is hope that safe agents of this type with oral activity may yet emerge. This active area of research and its historic context with alternative agents is reviewed herein.
Current Medicinal Chemistry 12/2013; 20(38):4859-87. DOI:10.2174/092986732038131128102220 · 3.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel one-pot sulfonylation/intramolecular thia-Michael protocol is reported for the synthesis of 1,5,2-dithiazepine 1,1-dioxides. Sulfonylation between cysteine ethyl ester/cysteamine and 2-chloroethanesulfonyl chloride, followed by in situ intramolecular thia-Michael addition, was achieved and afforded the titled 1,5,2-dithiazepine-1,1-dioxide scaffolds. Diversification was demonstrated for future library synthesis.
[Show abstract][Hide abstract] ABSTRACT: The synthesis of a library of bicyclic sultams incorporating the 1,5,2-dithiazepine 1,1-dioxide moiety is reported. Following scaffold synthesis via a one-pot sulfonylation/intramolecular thia-Michael protocol, several additional cyclization strategies have been realized enabling access to new bicyclic sultams.
[Show abstract][Hide abstract] ABSTRACT: In the title compound, C(15)H(14)N(2)O(5), the central amide C-C(=O)-N-C unit forms dihedral angles of 28.17 (13) and 26.47 (13)° with the two benzene rings, whereas the two benzene rings are almost coplanar, making a dihedral angle of 4.52 (13)°. The two meth-oxy and the nitro substituents are almost coplanar with their attached benzene rings, with C-O-C-C torsion angles of -1.3 (4) and -4.6 (4)°, and an O-N-C-C torsion angle of 17.1 (3)°. In the crystal, mol-ecules are linked via C-H⋯O and N-H⋯O inter-actions, forming a tape running along the b axis.
[Show abstract][Hide abstract] ABSTRACT: The asymmetric unit of the title compound, C(7)H(11)N(3)O(5)S, contains two independent mol-ecules with virtually identical conformations. The imidazole rings of both mol-ecules are essentially planar (r.m.s. deviations = 0.0019 and 0.0038 Å), with a dihedral angle 9.25 (19)° between them. The nitro groups are oriented at 4.5 (2) and 6.44 (13)° with respect to the imidazole rings. In the crystal, mol-ecules are linked to form a three-dimensional framework by C-H⋯O and C-H⋯N hydrogen bonds.
[Show abstract][Hide abstract] ABSTRACT: A series of metronidazole ester derivatives 1-34 has been synthesized with the aim of developing new leads with antiglycation activity. The in vitro evaluation of antiglycation potential of 1-34 showed that the ester derivatives 28, 16, and 3 have IC(50) values 218.97 ± 2.5, 245.3 ± 5.1, and 278.6 ± 0.8 µM, respectively, comparable to the standard agent, rutin (IC(50) = 294.5 ± 1.50 µM). The study identifies a new class of potent antiglycation agents. A structure-activity relationship has also been evaluated. All the compounds were characterized by using spectroscopic techniques, including (1)H NMR, IR, and EI-MS.
[Show abstract][Hide abstract] ABSTRACT: In the title compound, C(8)H(6)N(4)O(3), the ketone [C-C(=O)-C] and nitro groups are tilted with respect to the benzene ring by 18.92 (6) and 24.11 (15)°, respectively. In the crystal, mol-ecules are linked into inter-woven chains running parallel to the  direction by C-H⋯N hydrogen bonds and weak π-π stacking inter-actions, with centroid-centroid separations of 3.897 (3) Å.
[Show abstract][Hide abstract] ABSTRACT: In the mol-ecule of the title compound, C(9)H(9)N(3)O, the angle formed by the least-squares line through the azide group with the normal to the plane of the benzene plane ring is 46.62 (16)°. The crystal structure features C-H⋯O hydrogen bonds, which link the mol-ecules into zigzag chains running parallel to .
[Show abstract][Hide abstract] ABSTRACT: Kaempferol-3-O-α-L-rhamanopyranosyl-(1'''-6'')-β-D-glucopyranoside (1) (Nicotiflorin or kaempferol-3-O-rutinoside), isolated from the aerial parts of Osyris wightiana Wall. ex Wight, exhibited a potent antiglycation activity in vitro. A short and efficient route to kaempferol-3-O-rutinoside (1) is also described in this paper. To study the structure-activity relationship, few other derivatives of kaempferol were also evaluated for their antiglycation activity. Moreover the cytotoxicity analysis was also performed for these compounds. The Structure-Activity Relationship (SAR) studies showed that sugar derivatives of kaempferol possess a promising antiglycation activity.
[Show abstract][Hide abstract] ABSTRACT: The crystal structure of the title compound, C
O, is stabilized by C—H...O hydrogen bonds, which link the molecules into chains running parallel to the
[Show abstract][Hide abstract] ABSTRACT: The asymmetric unit of the title compound, C(17)H(13)N, contains two independent butterfly-shaped mol-ecules. The seven-membered azepine rings both adopt a boat conformation. The dihedral angles between the benzene rings in the two mol-ecules are 46.95 (11) and 52.21 (11)°.
[Show abstract][Hide abstract] ABSTRACT: In the title compound, C
, the dihedral angle between the benzene and imidazole rings is 32.77 (12)°. In the crystal, molecules are linked into a three-dimensional network by C—H...O hydrogen bonds.
[Show abstract][Hide abstract] ABSTRACT: In the title compound, C
, the dihedral angle between the benzene and imidazole rings is 30.6 (2)°. In the crystal, molecules are linked into chains parallel to  by C—H...O hydrogen bonds. The crystal packing is further consolidated by π–π interactions [centroid–centroid distance = 3.482 (2) Å].
[Show abstract][Hide abstract] ABSTRACT: A combination of MACOS scale-out and ROMP-derived oligomeric triazole phosphates (OTP(n)) have been successfully utilized for the preparation of a 106-member library of triazole containing benzothiaoxazepine-1,1-dioxides. This report demonstrates the utilization of a suite of soluble OTP(n) reagents for facile (triazolyl)methylation of 10 MACOS-derived sultam scaffolds in purification-free process for parallel synthesis of small molecule collections for HTS.
[Show abstract][Hide abstract] ABSTRACT: The synthesis of a unique isoindoline- and tetrahydroisoquinoline (THIQ)-containing tricyclic sultam library, utilizing a Heck-aza-Michael (HaM) strategy is reported. Both isoindoline and THIQ rings are installed through a Heck reaction on a vinylsulfonamide, followed by one-pot deprotection and intramolecular aza-Michael reaction. Subsequent cyclization with either paraformaldehyde condensation or 1,1'-carbonyldiimidazole coupling generates a variety of tricyclic sultams. Overall, a 160-member library of these sultams, together with their isoindolines/THIQ and secondary sulfonamides precursors, were constructed using this strategy.