Bhaskara Nand

Rapid Synthesis of Polyfunctionalized Pyrano[2,3-c]pyrazoles via Multicomponent Condensation in Room-Temperature Ionic Liquids

A highly efficient synthesis of 4H-pyrano[2,3-c]pyrazoles has been completed using four-component cyclocondensation of hydrazine monohydrate/phenyl hydrazine, ethyl acetoacetate, aldehydes, and malononitrile in the presence of L-proline and room-temperature ionic liquids.

An expedient four-component domino protocol for the synthesis of novel benzo[a]phenazine annulated heterocycles and their photophysical studies

A new one pot two-step domino protocol for the efficient synthesis of novel fluorescent benzo[a]phenazine fused derivatives has been developed. The synthesis was achieved by reacting 2-hydroxynaphthalene-1,4-dione, ortho-phenylenediamines, aromatic aldehydes and cyclic 1,3-dicarbonyl compounds in the presence of a catalytic amount of p-TSA in PEG-400 at 70 °C. The structural assignment has been unambiguously confirmed by X-ray analysis. The present finding provides an efficient and promising synthetic strategy for the synthesis of libraries with functional group diversity.

Synthesis and in vitro evaluation of antioxidant activity of diverse naphthopyranopyrimidines, diazaanthra[2,3-d][1,3]dioxole-7,9-dione and tetrahydrobenzo[a]xanthen-11-ones

A green and efficient one pot three component protocol has been developed for the synthesis of naphthopyranopyrimidines, diazaanthra[2,3-d][1,3]dioxole-7,9-dione and tetrahydrobenzo[a]xanthen-11-ones in PEG-400 catalyzed by alum (KAl(SO4)2·12H2O). Single crystal X-ray diffraction studies have been performed for naphthopyranopyrimidine (5). The synthesized compounds were screened for in vitro antioxidant activity by DPPH scavenging assay and compounds 3 and 4 manifested profound antioxidant potential.

Efficient and Green Syntheses of 12-Aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-triones in Water and Task-Specific Ionic Liquid

Abstract Facile and convenient one-pot cascade/tandem approaches for the syntheses of privileged medicinal scaffolds, 12-aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-trione derivatives, have been reported under extremely mild reaction conditions using a catalytic amount of H2SO4 in water or in the presence of the acidic ionic liquid bmim[HSO4], which could be recycled. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

Aqueous sodium hypochlorite mediated chemoselective oxidation of chalcogenides to monoxides and dioxides by microwave exposure

A solvent-free, rapid, and highly selective oxidation of sulfides, selenides, and tellurides (chalcogenides) to the corresponding monoxides (sulfoxides, selenoxides, and telluroxides) or the corresponding dioxides (sulfones, selenones, and tellurones) has been developed using aqueous sodium hypochlorite on solid supports by exposure to microwave. Chemoselectivity and quantitative yields have been attained in most cases.

Efficient one pot synthesis of xanthene-triazole-quinoline/phenyl conjugates and evaluation of their antimicrobial activity

Novel xanthene-triazole-quinoline/phenyl conjugates were synthesized by eco-friendly one pot three-component condensation of 12-aryl-2-hydroxy-tetrahydrobenzo[a]xanthene-11-one, propargyl bromide and 4-azido-7-chloroquinoline/phenyl azide using polyethylene glycol (PEG-400) as a reaction medium with an aim to explore their effect on the invitro growth of microorganisms causing microbial infection. All newly synthesized xanthene-triazole-quinoline/phenyl conjugates were fully characterized and were evaluated for invitro antibacterial and antifungal activity. Antimicrobial activity was evaluated against nine microbial strains. All compounds showed good Gram positive antibacterial and antifungal activity. One of the compounds showed best antibacterial and antifungal activity. Further, binding mode of this compound at the active site of enzyme topoisomerase II DNA gyrase B has also been investigated.

Synthesis and characterization of hybrid chloroquinoline–xanthene derivatives

Abstract A novel series of chloroquinoline-xanthene hybrids were prepared by one-pot multicomponent cyclo-condensation reaction of 2,7-dihydroxynaphthalene, aromatic aldehydes, and cyclic 1,3-dicarbonyl compounds followed by condensation reaction with 4,7-dichloroquinoline. The synthesized compounds were characterized by various spectroscopic techniques and single crystal X-ray analysis.

Metal-free synthesis of 1,2,3-triazoles by azide–aldehyde cycloaddition under ultrasonic irradiation in TSIL [DBU-Bu]OH and in hydrated IL Bu4NOH under heating

Efficient and environmentally benign procedures have been reported for the synthesis of 1,4-disubstituted 1,2,3-triazoles by reaction of aryl azides with aldehydes in task-specific basic ionic liquid [DBU-Bu]OH under ultrasonic irradiation and in hydrated ionic liquid tetrabutylammonium hydroxide (Bu4NOH) under conventional heating. These protocols represent simple, general, and efficient approaches in terms of good yields, operational simplicity, easy workup, and shorter reaction time for the synthesis of 1,4-disubstituted 1,2,3-triazoles under metal-free conditions.Graphical Abstract