Anshika Lumb

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.

Green Approaches for the Synthesis of 12-Aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones in Aqueous Media and Under Microwave Irradiation in Solventless Conditions

Abstract Convenient and environmentally benign procedures have been reported for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives by multi component condensation reactions of aromatic aldehydes with β-naphthol and cyclic 1,3-dicarbonyl compounds, namely, dimedone and cyclohexane-1,3-dione. The three-component condensation has been successfully achieved in one pot by refluxing the components in water and is efficiently catalyzed by sulfuric acid. The condensation has also been achieved by irradiating the components in the presence of a catalytic amount of para-toluene sulfonic acid under neat conditions with microwaves. The green methodologies defined herein avoid the severe conditions posed by the older existing methods and prove to be efficient in terms of good yields, operational simplicity, easy workup, and short reaction time. GRAPHICAL ABSTRACT

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

A simple, mild and environmentally benign procedure for the cleavage of carbon–nitrogen double bonds using NaBrO3 in the presence of [bmim]HSO4

A clean, mild and efficient deprotection of oximes, hydrazones, phenyl hydrazones, tosylhydrazones, Schiffs bases and azines to their corresponding carbonyl compounds has been developed using sodium bromate in the presence of acidic ionic liquid [bmim]HSO4 at 60 °C. The experimental procedure is simple and the products are isolated in high yields. The ionic liquid [bmim]HSO4 could be easily recovered and recycled.

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.

NaBrO3/bmim[HSO4]: a versatile system for the selective oxidation of 1,2-diols, α-hydroxyketones, and alcohols

Sodium bromate with bmim[HSO4] has been found to be an excellent oxidizing agent in aqueous medium. NaBrO3:bmim[HSO4] oxidized 1,2-diols, α-hydroxyketones, and alcohols to the corresponding carbonyl compounds in excellent yields. This method offers advantages such as low cost reagents, aqueous reaction conditions, moderate temperatures and short reaction times and hence environmentally benign reaction. Moreover, the ionic liquid bmim[HSO4] could be recycled for at least three times without loss of significant activity.Graphical abstract

Facile Deoxygenation of Telluroxides, Tellurones and Selenones with Nickel Boride at Ambient Temperature

Nickel boride has been reported as a convenient and efficient reagent in numerous transformations.1–5 It is superior to many other metal catalysts due to its low cost, ease of preparation and handling, non-pyrophoric nature and easy removal. Unlike its initial applications as a heterogeneous catalyst, nickel boride is used as a reducing agent without aid of hydrogen as it contains adsorbed hydrogen.1 Nickel boride, prepared in situ, has been reported for a variety of applications such as, reductions,6 deoxygenations,7 desulfurizations,8 etc. In continuation of our studies on the deoxygenation of sulfoxides and selenoxides,9 and in view of the paucity of the reagents for the deoxygenation of chalcogenide monoxides10–12 and especially chalcogenide dioxides,13 we attempted to develop new methodologies using nickel boride and now report the deoxygenation of aryl, alkyl and aralkyl telluroxides, tellurones and selenones with nickel boride generated in situ from nickel(II) chloride and sodium borohydride in different solvents at ambient temperature to give the corresponding tellurides and selenides respectively. Di(4-tolyl)telluroxide (1a) was chosen as a model substrate to investigate and optimize the conditions for the deoxygenation. The reactions were carried with nickel boride generated in situ in different solvents such as MeOH, THF, DMF and dioxane, and in different molar ratios of substrate to nickel boride. It was observed that deoxygenation of di(4-tolyl)telluroxide could be achieved with anhydrous NiCl2 and sodium borohydride in dry THF using 1:1:3 molar ratio of substrate:NiCl2:NaBH4 at ambient temperature to give 86% of di(4-tolyl)telluride (2a). The protocol was then extended to a variety of aryl, alkyl and aralkyl telluroxides. All the telluroxides underwent deoxygenation to give corresponding tellurides in high yields (Table 1). Halo substituents were unaffected under these