Bharti Khungar

Copper-catalyzed tandem azide-alkyne cycloaddition, Ullmann type C-N coupling, and intramolecular direct arylation.

A ligand-free copper-catalyzed tandem azide-alkyne cycloaddition (CuAAC), Ullmann-type C-N coupling, and intramolecular direct arylation has been described. The designed strategy resulted in the synthesis of a novel trazole-fused azaheterocycle framework. The reaction gave good yields (59-77%) of 1,2,3-triazole-fused imidazo[1,2-a]pyridines in a single step.

One-pot sequential C–N coupling and cross dehydrogenative couplings: synthesis of novel azole fused imidazo[1,2-a]pyridines

An efficient one-pot protocol has been developed using sequential C-N coupling and intramolecular dehydrogenative cross-couplings for the synthesis of azole fused imidazo[1,2-a]pyridine derivatives in good yields (62-78%).

A simple and facile synthesis of amidoalkyl naphthols catalyzed by Yb(OTf)3 in ionic liquids

An improved, simple, and facile synthesis of amidoalkyl naphthols by employing three-component one-pot condensation reaction of β-naphthol, aromatic aldehydes, and amides in ionic liquids using ytt...

Imidazolium ionic liquid-tagged palladium complex: an efficient catalyst for the Heck and Suzuki reactions in aqueous media

An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology.

An Efficient and Simple One-Pot Synthesis of β-Acetamido Ketones Catalyzed by Ytterbium Triflate in Ionic Liquid

Ytterbium triflate immobilized in the ionic liquid [bmim][BF4] catalyzes the three-component coupling of aromatic aldehydes, enolizable ketones, and acetonitrile in the presence of acetyl chloride at room temperature to afford β-acetamido ketones in good yields. The catalyst can be recovered and recycled for subsequent reactions without any appreciable loss of efficiency.

COORDINATION BEHAVIOR OF BIOLOGICALLY ACTIVE SCHIFF BASES OF AMINO ACIDS TOWARDS SILICON(IV) ION

Abstract Reactions of diethoxydimethylsilane with Schiff bases derived from the condensation of fur-furaldehyde. indole-3-carbaldehyde with alanine, glycine, valine, isoleucine and tryptophan in a 1:2 molar ratio give a new series of Me2Si (NO)2 type of organosilicon (IV) complexes. The complexes are monomeric and non-electrolytic in nature. The coordination behaviour of Schiff babes through organosilicon (IV) has been investigated by IR, 1H, 13C & 29Si NMR spectral studies. Schiff bases and their silicon complexes have also been screened for their antifungal activity. Several of these complexes were found to be quite active in this respect.

Recyclable imidazolium ion-tagged nickel catalyst for microwave-assisted C–S cross-coupling in water using sulfonyl hydrazide as the sulfur source

Herein, we report the facile and convenient synthesis of aryl sulfides through the sulfenylation of aryl halides with arylsulfonyl hydrazides, which is catalyzed by a simple and water-soluble Ni(II) complex. The nickel complex based on the imidazolium ion-tagged salen architecture is synthesized and well characterized using various analytical techniques. The green solvent water is used as the solvent medium and moderate to good yields of aryl sulfides are obtained using 5 mol% of the catalyst under microwave irradiation. The incorporation of the ion-tag functionality helps in the recycling of the catalyst and successful reuse for up to five runs without appreciable change in its activity.

Multinuclear Magnetic Resonance and Related Studies of Coordination Compounds of Organosilicon with Mixed Azines

New hexa-coordinated complexes of organosilicon (IV) have been synthesized by the reactions of diethoxydimethylsilane with the mixed azines. Their structures have been inferred based on elemental analysis, UV, IR, and multinuclear magnetic resonance spectral studies. The monomeric and nonelectrolytic nature of these complexes has been confirmed by molecular weight determinations and conductance measurements. The mixed azines and their silicon complexes also have been screened for their antimicrobial activities against several fungi and bacteria and were found to be quite active in this respect.