Synthesis of Sulfur Containing Organic Compounds Using Multicomponent Reactions (MCRs): Their Biological and Photophysical Studies
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The synthesis of a wide variety of sulfur containing organic compounds such as highly substituted unsymmetrical sulfides starting from 1,3-dicarbonyl compounds and aromatic aldehydes to form Knoevenagel intermediate and subsequent addition of thiols via thia-Michael using piperidine catalyst, through multicomponent reactions (MCRs) and their oxidation in to corresponding sulfones by using mchloroperoxybenzoic acid (m-CPBA) to find out effective antileishmanial agents. Next, the synthesis of 4- hydroxy-3-thiomethylcoumarin derivatives was carried out by using one-pot three-component reaction strategy via a domino process comprising of a Knoevenagel type condensation between 4- hydroxycoumarin and aldehyde, followed by a thia-Michael addition onto the resulting unsaturated ketone, thereby generation of highly functionalized 4-hydroxy-3-thiomethylcoumarin derivatives. Furthermore, the derivative displays its optical properties as a “turn-off” fluorescence probe towards cobalt and nickel ions in aqueous based media selectively, in presence of commonly coexisting metal ions. These two metal complexes were further distinguished by EDTA induced fluorescence recovery that was only possible towards cobalt (II) complex via “turn-on” photoluminescence response. Moreover, the synthesis of unsymmetrical sulfides by trapping 2-naphthoquinone-1-methide intermediates, generated in situ from 2- naphthol and aromatic aldehydes, with thiols in the presence of environmentally benign reagent nterabutylammonium tribromide (TBATB) was performed. In addition, the unsymmetrical sulfide was capable of performing detection of mercury ions in aqueous medium at high pH selectively, the utility of this compound as a “turn-on” fluorescence sensor are of practical importance. Later, the synthesis of 3- [(alkyl/arylthio)(aryl)methyl]-1H-indoles at room temperature from indole, aromatic aldehyde and thiol mediated by hydrated ferric sulfate (Fe2(SO4)3•xH2O) using one-pot three-component reaction. The synthesized indole derivative served as a chemosensor for Hg2+ and Cu2+ ions. Finally, the synthesis of Salkyl/ aryl benzothiazole-2-carbothioate from thiols, oxalyl chloride and 2-aminothiophenols using ntetrabutylammonium iodide (TBAI) as catalyst in acetonitrile through multicomponent reaction (MCR) strategy. Few of the synthesized derivatives were evaluated for their antimicrobial activity against the protozoan parasite, Leishmania donovani, a causative agent of visceral leishmaniasis (VL). Further, insilico docking studies were performed to understand the possible binding site interaction with trypanothione reductase (TryR).
Supervisor: A.T. Khan