Appaswami Lalitha

An efficient green chemistry protocol for the synthesis of novel spiropyrrolizidine compounds

An efficient method for the synthesis of spirooxindolopyrrolizidine/spirooxindolothiapyrrolizidine by the 1,3-dipolar cycloaddition of azomethine ylides generated via, decarboxylative condensation of 1,2-dicarbonyl compounds and L-proline/L-thiaproline/sarcosine with chalcones at ambient conditions with excellent yields has been described.

PEG-assisted two-component approach for the facile synthesis of 5-aryl-1,2,4-triazolidine-3-thiones under catalyst-free conditions

A straightforward and greener PEG-assisted protocol has been disclosed for the facile synthesis of 5-aryl-1,2,4-triazolidine-3-thiones via the two-component reaction of multifarious aromatic aldehydes and thiosemicarbazides using very convenient neutral reaction conditions. This methodology represents a sustainable approach for rapid access to a library of diversity-oriented highly pure triazolidine scaffolds with broad substrate scope.

Zeolite H‐Y–Supported Copper(II) Nitrate: A Simple and Effective Solid‐Supported Reagent for Nitration of Phenols and Their Derivatives

Abstract Highly regiospecific mononitration of phenols and substituted phenols is accomplished by employing copper(II) nitrate supported on a catalytic amount of zeolite H‐Y in a solid state.

Synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones using boric acid-functionalized MCM-41 as a novel heterogeneous catalyst under solvent-free condition

Ordered mesoporous silica material MCM-41 with covalently anchored boric acid groups located inside the mesochannels has been utilized as an acid catalyst for the ‘green’ synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-one derivatives under solvent-free condition. This novel synthetic method offers advantages, such as excellent yields, simple reaction procedure, short reaction times and mild reaction conditions.

Synthesis of pyran annulated heterocyclic scaffolds: a highly convenient protocol using dimethylamine

A facile and rapid three-component synthesis of pharmaceutically diverse pyran annulated heterocycles has been developed via a one-pot condensation of aromatic aldehydes, malononitrile, and different enolizable C–H-activated acidic compounds in the presence of dimethylamine as a newer and effective organo-catalyst in ethanol under mild reaction conditions. Selectivity of various pyran derivatives depends on the structure of enolates. The present protocol has synthetic advantages of excellent yields in much shorter reaction times with no chromatography.

Synthesis of novel bis(pyrimido[5,4-c]quinoline-2,4(1H,3H)-dione) and its derivatives: evaluation of their antioxidant properties.

One pot cyclocondensation reaction of barbituric/thiobarbituric acid with aromatic aldehydes and p-phenylenediamine/2,6-diaminopyridine by refluxing in glacial acetic acid afforded novel bis(pyrimido[5,4-c]quinoline-2,4(1H,3H)-diones)/pyrido bis(pyrimido[5,4-c]quinoline-2,4(1H,3H)-diones. All the synthesized compounds were screened for their antioxidant activities using FRAP and DPPH methods. Compounds with chloro substituents showed relatively good antioxidant properties.

WATER-MEDIATED STRECKER REACTION: AN EFFICIENT AND ENVIRONMENTALLY FRIENDLY APPROACH FOR THE SYNTHESIS OF α-AMINONITRILES VIA A THREE-COMPONENT CONDENSATION

The synthesis of α-aminonitriles by a direct three component Strecker reaction has been achieved in water, which is found to be an inexpensive, non-toxic and eco-friendly reaction medium for the nucleophilic addition. This protocol is effective to a wide variety of substrates with different functional groups and does not require the use any other catalyst.

Glycerol assisted eco-friendly strategy for the facile synthesis of 4,4'-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) and 2-aryl-2,3-dihydroquinazolin-4(1H)-ones under catalyst-free conditions

This article describes glycerol mediated eco-friendly approaches for the convenient access of structurally diverse 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ol) and 2-aryl-2,3-dihydroquinazolin-4(1H)-one motifs under catalyst-free conditions. Prominent advantages include clean processes, atom-efficiency, simplicity of the work-up, neutral conditions, low-cost reaction medium, excellent product yield and solvent reusability, in addition to relatively shorter reaction times.Graphical Abstract

Click and facile access of substituted tetrahydro-4H-chromenes using 2-aminopyridine as a catalyst

A highly convenient and greener method for the facile synthesis of pharmaceutically diverse 2-amino-5-oxo-4-aryl-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles via a one-pot, three component condensation of aromatic aldehydes, malononitrile, and 1,3-cyclohexanedione or dimedone using 2-aminopyridine as an efficient alkaline organo catalyst is described. This new chemistry furnishes the desired heterocycles in very shorter reaction times with higher purity and has the advantages of economic viability, ease of preparation, excellent yields, and recyclability of catalyst.Graphical Abstract

Catalyst-free one-pot synthesis and antioxidant evaluation of highly functionalized novel 1,4-dihydropyridine derivatives

A catalyst-free greener protocol for the most effective one-pot synthesis of 2,6-diamino-4-aryl-1-propyl/cyclohexyl-1,4-dihydropyridine-3,5-dicarbonitrile derivatives has been developed using a simple three-component reaction of structurally diverse aldehydes, malononitrile and n-propylamine/cyclohexylamine at an ambient temperature. The formation of 1,4-dihydropyridines could be achieved in aqueous methanol in a single synthetic process involving no chromatography. The newly synthesized highly functionalized 1,4-DHPs have been screened for their in vitro antioxidant activity using the DPPH radical scavenging technique and the results were good in comparison with a standard drug.