Nidhi Jain

Palladium-Catalyzed Regioselective Decarboxylative Alkylation of Arenes and Heteroarenes with Aliphatic Carboxylic Acids

An unprecedented Pd(OAc)2-catalyzed decarboxylative alkylation of unactivated arenes, with aliphatic carboxylic acids as inexpensive alkyl sources, is reported. The alkylation, controlled by the directing group, is regioselective, shows high functional group tolerance, and provides mild access to alkylated indolines, 2-phenylpyridines, and azobenzenes under solvent-free conditions in moderate to high yields.

One-Pot Sequential Alkynylation and Cycloaddition: Regioselective Construction and Biological Evaluation of Novel Benzoxazole–Triazole Derivatives

Individually, benzoxazole and triazole moieties are of significant biological interest owing to their importance in drugs and pharmaceuticals. To assess their combined biological impact when woven into one molecule, we designed a novel, regioselective, multicomponent, one-pot (MCOP) approach for the construction of benzoxazole-linked triazoles. The synthesis has been achieved in two sequential steps involving copper-catalyzed alkynylation of benzoxazole followed by a 1,3-dipolar cycloaddition reaction. By combination of these two bioactive units into one core, a series of new benzoxazole-triazole scaffolds has been synthesized and subjected to in vitro antibacterial and anticancer evaluation. Tests against clinical isolates of Staphylococcus aureus and Escherichia coli showed potent Gram-negative activity for compounds 4{1,1,1}, 4{1,1,4}, and 4{1,2,1}. The cytotoxicity of the synthesized library was determined against three cancer cell lines: HeLa, SKBr3, and Hep G2. Compound 4{2,2,2} showed significant cytotoxicity against all the cell lines. These preliminary bioassay evaluations strongly suggest the promise and scope of these novel molecules as therapeutic agents in medical science.

Pd/mannose promoted tandem cross coupling-nitro reduction: expedient synthesis of aminobiphenyls and aminostilbenes

The dual role of D-mannose as a ligand for Pd catalyzed cross-coupling, and as a hydrogen source for nitro reduction is demonstrated in a modular cross coupling-nitro reduction sequence. The synthetic utility and generality of this green protocol has been illustrated by the synthesis of 20 aminobiphenyl and 10 aminostilbene derivatives in high yields through a one-pot Suzuki coupling-nitro reduction and a Heck coupling-nitro reduction, respectively, starting from halonitroarenes as substrates.

Synthesis and spectroscopic studies of some diamine platinum(II) complexes of diethyldithiocarbamate

Abstract The complexes of the type [Pt(LL)(DDTC] NO3 (where LL = en or pn) have been prepared and characterized by various physical methods. The conductivity data of the above complexes in conductivity water suggests they are 1:1 electrolytes. The electronic absorption spectra of these complexes can be interpreted in terms of their square planar geometry. The infrared (IR) spectra support the bonding of DDTC as bidentate complexes in these complexes. The 1H nuclear magnetic resonance (NMR) spectra of these complexes in D2O indicate that the two conformations of the ethylenediamine or propylene- diamine chelate ring are rapidly exchanging. The 1H NMR spectra further suggest that the C ··· N double bond character in bonded DDTC of the above complexes is increased as compared to free DDTC.

Dual SNAr reaction in activated ortho-halonitrobenzene: direct synthesis of substituted 1,2,3,4-tetrahydroquinoxalines, 2,3-dihydro-1,4-benzoxazines, and 1,4-benzodioxines

An unprecedented one-pot synthesis of substituted 1,2,3,4-tetrahydroquinoxalines, 2,3-dihydro-1,4-benzoxazines, and 1,4-benzodioxines from activated ortho-halonitrobenzenes has been accomplished by dual nucleophilic aromatic substitution (SNAr) of halogen followed by substitution of the nitro group by secondary diamines, secondary amino alcohols, and diols respectively.

Graphene oxide decorated with Cu(I)Br nanoparticles: a reusable catalyst for the synthesis of potent bis(indolyl)methane based anti HIV drugs

A GO–Cu(I)Br nanocatalyst has been prepared, and applied for the synthesis of bis(indolyl)methanes. The catalyst is highly effective, is required in much lower amounts (0.05 mol%), and is recyclable for up to six reaction cycles without loss in activity. The synthesized compounds have been screened for their in vitro anti-HIV-1 activity, and compound 3d has shown significant anti-HIV-1 effects. Molecular modelling of 3d with reverse transcriptase enzyme has been carried out to understand its binding mechanism to the active enzyme site.

Aryl alkyl carbene–Pd complex assisted C–Cl bond activation: an unprecedented cross-coupling route to trans-stilbenes

Palladium catalyzed cross-coupling with aryl chlorides has always been a challenge and does not take place without the assistance of bulky phosphine ligands, NHCs or other additives. In this work, we present an unprecedented phosphine-free coupling of cheap and less reactive substrates like aryl chlorides with 1-(bromoethyl)benzene as a nucleophilic coupling partner at low Pd concentrations, under microwave conditions to access highly regio- and stereospecific trans-stilbene derivatives. The reaction is believed to proceed via a Pd–carbene intermediate generated in situ under MW conditions from 1-(bromoethyl)benzene. Another key requirement in the reaction is the presence of styrene; as in its absence, Pd catalysed coupling of halogenated ethyl benzene with chloroarenes does not take place at all. DFT studies have also been carried out to obtain a thermodynamic insight into the proposed mechanism.

Synthesis, characterization, cytotoxicity and DNA binding studies of diamminediethyldithiocarbamato-platinum(II) nitrate

A new complex [Pt(NH3)2(ddtc)]NO3.2H2O as a 1:1 electrolyte has been prepared. This was characterized by spectroscopic methods. The electronic absorption spectrum of this complex in water suggests that it has a square planar geometry. The infrared, 1H NMR and x-ray photoelectron spectroscopic studies suggest the bonding of ammonia molecules and diethyldithiocarbamate as bidentate ligand to platinum(II) in this complex. The 50% inhibition value of this complex against P388 lymphocytic leukemia cells is comparable with cisplatin. This complex interacts with calf thymus DNA by coordinate covalent bond.

Improvising 5-HT7R homology model for design of high affinity ligands: model validation with docking, embrace minimization, MM-GBSA, and molecular dynamic simulations

The subtype, 5-HT7R has been implicated in neurological disorders and presents itself as a promising target for antidepressant drugs. Design of targeted selective ligands, require a sound knowledge of 3D-receptor structure. In absence of receptor structure, structure-based design of targeted ligands relies on generation of 5-HT7R homology model. In this study, the impact of template choice, alignment, and model building methods on the homology model of 5-HT7R is addressed. The compactness and model quality due to the presence of cholesterol (lipidic receptor) have also been observed. The results suggest good stereochemical quality of the final model. Ramachandran Plot Analysis indicated more than 97.5% amino acid residues in the favorable region. The overall quality factor was 91.8% using ERRAT. The Z-score for backbone confirmation and packing quality were −1.248 and −1.427, respectively, using WHATCHECK. The RMS Z-score for side chain planarity was .711. Other validation results for the final model include binding site analysis in which Asp162, Val163, Phe343, Phe344, Arg350, Arg367, and Leu370 conserved residues were found in the active site, correlation coefficient of .82 in ligand-based screening and .85 in embrace minimization. Further, the model showed good correlation for agonist and antagonist in docking ( ≈ .76, ≈ .82), embrace minimization ( ≈ .73, ≈ .72), and MM-GBSA ( ≈ .69, ≈ .75) studies. The model was subjected to Molecular Dynamics (MD) simulation of 20 ns both in ligand-free and ligand-bound receptor (agonist and antagonist) system in order to assess its stability.

Glucose promoted facile reduction of azides to amines under aqueous alkaline conditions

A quick and efficient method for the reduction of azides to amines in water using D-glucose and KOH as green reagents is reported. The protocol is simple, inexpensive, scalable, and can be applied to different aromatic, heteroaromatic and sulphonyl azides. A high level of chemoselectivity is observed for azide reduction in the presence of other reducible functionalities like cyano, nitro, ether, ketone, amide and acid. The reaction gets completed in a short time (5–20 minutes), and furnishes the amines in high yield (85–99%). Unlike conventional hydrogenations, this reduction protocol does not require any metal catalyst, elaborate experimental setup or use of high-pressure equipment.