Shanmugam Muthusubramanian

A facile, water mediated, microwave-assisted synthesis of 4,6-diaryl-2,3,3a,4-tetrahydro-1H-pyrido[3,2,1-jk]carbazoles by a domino Fischer indole reaction–intramolecular cyclization sequence

An environmentally benign, facile and efficient synthesis of a series of 4,6-diaryl-2,3,3a,4-tetrahydro-1H-pyrido[3,2,1-jk]carbazoles was achieved in water with good yield by the reaction of diastereomerically pure 2-(3-oxo-1,3-diarylpropyl)-1-cyclohexanones with phenylhydrazine hydrochloride under microwave irradiation. The transformation presumably proceeds via a domino Fischer indole reaction–intramolecular cyclisation sequence.

Pyrazole derivatives from azines of substituted phenacyl aryl/cyclohexyl sulfides and their antimycobacterial activity

Azines derived from substituted phenacyl aryl/cyclohexyl sulfide on treatment with excess phosphorous oxychloride in N,N-dimethylformamide have been found to yield two isomeric pyrazoles in each case. A plausible mechanism has been suggested for the formation of the products. The antimycobacterial activity of the isomeric compounds has been tested against Mycobacterium tuberculosis (MTB).

Erbium triflate promoted multicomponent synthesis of highly substituted imidazoles.

The synthesis of highly substituted imidazole derivatives has been achieved from various α-azido chalcones, aryl aldehydes, and anilines. This multicomponent protocol employs erbium triflate as a catalyst resulting in excellent yield of the imidazoles.

SnCl2-catalyzed selective atom economic imino Diels-Alder reaction: synthesis of 2-(1H-pyrrolo[2,3-b]pyridin-3-yl)quinolines.

The synthesis of 2-(1H-pyrrolo[2,3-b]pyridin-3-yl)quinolines by a SnCl(2)-catalyzed multicomponent reaction has been described. The reaction proceeds chemo- and regioselectively in an atom-economic way, generating a library of 24 quinoline derivatives.

Silver catalyzed decarboxylative acylation of pyridine-N-oxides using α-oxocarboxylic acids

Silver catalyzed acylation of pyridine-N-oxides by α-oxocarboxylic acid is demonstrated. This decarboxylative acylation using a metal catalyst takes place at 50 °C via a radical process.

Synthesis of 3-heteroarylthioquinoline derivatives and their in vitro antituberculosis and cytotoxicity studies.

A series of 3-heteroarylthioquinoline derivatives has been synthesized by the Friedlander annulation of 2-[(5-methyl-1,3,4-thiadiazol-2-yl)sulfanyl]-1-aryl-1-ethanone/2-(1,3-benzothiazol-2-ylsulfanyl)-1-aryl-1-ethanone/1-aryl-2-[(2-phenyl-2H-1,2,3,4-tetraazol-5-yl)sulfanyl]-1-ethanone with 2-aminobenzophenone in good yields using YbCl(3) as the catalyst. These compounds have been screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and among the 21 compounds screened, 2-[2-(4-bromophenyl)-4-phenyl-3-quinolyl]sulfanyl-5-methyl-1,3,4-thiadiazole (5d) and 2-[2-(4-chlorophenyl)-4-phenyl-3-quinolyl]sulfanyl-5-methyl-1,3,4-thiadiazole (5c) were found to be the most active compounds with MIC of 3.2 and 3.5 μM respectively against MTB. The cytotoxic effects against mouse fibroblasts (NIH 3T3) in vitro were evaluated for 5c and 5d, which displayed no toxic effects (IC(50) > 1000 μM) against the mouse fibroblast cell line NIH 3T3.

Copper(I)-Catalyzed Cascade Sulfonimidate to Sulfonamide Rearrangement: Synthesis of Imidazo[1,2-a][1,4]diazepin-7(6H)-one

A novel strategy of copper(I)-catalyzed cascade intramolecular nucleophilic attack on N-sulfonylketenimine followed by rearrangement of sulfonimidates to sulfonamides resulting in a library of substituted 8,9-dihydro-5H-imidazo[1,2-a][1,4]diazepin-7(6H)-ones has been developed.

Hypervalent Iodine(III) Mediated Synthesis of 3-Substituted 5-Amino-1,2,4-thiadiazoles through Intramolecular Oxidative S–N Bond Formation

An efficient synthesis of 3-substituted-5-arylamino-1,2,4-thiadiazoles through intramolecular oxidative S-N bond formation of imidoyl thioureas by phenyliodine(III) bis(trifluoroacetate) is reported. The protocol features a metal-free approach, broad substrate scope, very short reaction times, good to excellent yields, and simple starting materials.

Synthesis of Highly Substituted 2,3-Dihydro-1H-pyrrole Derivatives via a Tandem Regioselective Addition of Nitrones to 1,3-Enynes with Subsequent Rearrangement

A novel method for the synthesis of 1,3-enynes is described through oxidative cyclization of the semicarbazones of Michael adducts having potential nitrile functionality. Reaction of these 1,3-enynes with diaryl nitrones has yielded a diastereomeric mixture of highly substituted 2,3-dihydro-1H-pyrrole derivatives via a tandem regioselective addition with subsequent rearrangement.

Aggregation induced emission characteristics of maleimide derivatives

A simple microwave assisted protocol for the construction of maleimides from various anilines and dialkyl acetylene dicarboxylates has been demonstrated. The AIE property of one of the maleimide derivatives has been studied in detail. The maleimide is AIE-active, and its color, fluorescence efficiency, quantum yield and fluorescence lifetime can be readily tuned by adding water to the THF solution. Compound 3a is found to be weakly luminescent when it is dissolved in THF, but its luminescence intensity increases enormously by the gradual addition of water up to 90% with associated increase in quantum yield and fluorescence lifetime.