Rajendran Satheeshkumar

Efficient Protocol for Synthesis of Pyrazolo[3,4-a]acridines

Abstract A new class of pyrazolo[3,4-a]acridines have been prepared. The synthon acridones were obtained in very good yield by a one-pot reaction of 2-amino-5-chloro or nitro substituted benzophenones with 1,3-cyclic diketones in the presence of freshly prepared Eaton’s reagent without solvent, using Friedländer synthesis. The intermediates were reacted with ethylformate followed by hydrazine hydrate to afford pyrazolo[3,4-a]acridines. All of the compounds were purified by recrystallization only, and no chromatographic workup was required. The structures of the synthesized compounds were deduced by spectroscopic techniques, including single-crystal x-ray diffraction. GRAPHICAL ABSTRACT

Efficient novel synthesis of pyrano[3,2-a]- and pyrazolo[4,3-a]-acridines

ABSTRACT The synthesis of pyrano[3,2-a]acridines is presented, where 7-chloro-9-phenyl-2,3-dihydroacridin-4(1H)-one reacts with arylaldehydes and malononitrile in the presence of piperidine in ethanol, giving with high yield via a multicomponent method. Also a new synthesis of pyrazolo[4,3-a]acridines is reported, where 7-chloro-9-aryl-2,3-dihydroacridin-4(1H)-one on Claisen condensation with ethylformate followed by hydrazine hydrate treatment through the intermediate 7-chloro-4-hydroxy-9-aryl-1,2-dihydroacridin-3-carbaldehyde. The structures of newly synthesized compounds were deduced by spectroscopic techniques, elemental analysis, and single-crystal x-ray diffraction. GRAPHICAL ABSTRACT

Synthesis, spectroscopic, in vitro cytotoxicity and crystal structures of novel fluorinated dispiroheterocycles: DFT approach

The reaction of azomethine ylide generated in situ from ninhydrin and sarcosine/thiaproline with fluorinated cyclopent[b]indole dipolarophiles in refluxing dioxane and methanol afforded a novel class of fluorinated cyclopent[b]indole dispiroheterocycles via 1,3-dipolar cycloaddition. The crystal structures of 4′-[4-(trifluoromethyl)phenyl]-1′,5-dimethyl-2,3-dihydrodispiro[cyclopent[b]-indol-2,3′-pyrrolidine-2′,2″-indene]-1,1″,3″-trione and 4′-(4-fluorophenyl)-5-methyl-2,3-dihydrodispiro[cyclopent[b]indol-2,3′-pyrrolizidine-2′,2″-indene]-1,1″,3″-trione are reported. New compounds are investigated theoretically via DFT calculations utilizing M062X hybrid function with 6-311++G(d,p) basis sets in vacuum. Results from in vitro cytotoxicity screening are compared with those of standard drugs.Graphical abstract

Indium triflate and ionic liquid-mediated Friedländer synthesis of 2-acylquinolines

ABSTRACT Friedländer synthesis of 2-acylquinolines from the reaction of symmetrical and unsymmetrical 1,2-diketones with 2-aminoarylketones in the presence of indium triflate (In(OTf)3) and ionic liquid gives quantitative yields. Once the reaction was completed, the catalysts can be recovered and subsequently run for next cycles. Results obtained from theoretical studies have been more strengthened by FT-IR, FT-NMR chemical shifts, and structural parameters which were attained with B3LYP/6-31G(d,p) level of theory and the related results were demonstrated with the experimental interpretations. GRAPHICAL ABSTRACT

Solvent Free Synthesis of Dibenzo[b,j][1,10]Phenanthroline Derivatives Using Eaton's Reagent as Catalyst

ABSTRACT A new class of dibenzo[b,j][1,10]phenanthrolines has been prepared. The synthon acridones were achieved in very good yield by a one-pot reaction of 2-amino-5-chloro or 2′-chloro/flouro-substituted benzophenones with 1,2-cyclohexanedione in the presence of freshly prepared Eaton’s reagent (phosphorus pentoxide–methanesulfonic acid) without solvent, through Friedländer synthesis. Then these intermediates were reacted with 2-amino-3,5-dibromobenzaldehyde to afford 1,3-dibromo-10-chloro-8-aryl-6,7-dihydrodibenzo[b,j][1,10]phenanthroline. Also an one-pot reaction between 2 mol of 2-amino-5-chloro aryl benzophenones with 1 mol of 1,2-cyclohexanedione to get 3,10-dichloro-5,8-diaryl-6,7-dihydrodibenzo[b,j][1,10]phenanthroline has also been reported. The newly synthesized structures of the compounds were deduced by spectroscopic techniques. GRAPHICAL ABSTRACT

Synthesis of heteroannulated cyclopent[b]indoles: Exploration of in vitro cytotoxicity and molecular docking studies

ABSTRACT A series of novel cyclopent[b]indole analogues that hold isoxazolo-, pyrido-templates were designed and synthesized in good yields. The in vitro cytotoxicity was concerned for all the newly synthesized compounds by MTT assay against HeLa (cervix adeno carcinoma) and MCF-7 (breast cancer). These synthesized compounds were further compared with the standard drug ellipticine, 5-fluorouracil, cisplatin, and methotrexate. The synthesized heteroannulated cyclopent[b]indole compounds were found to show better cytotoxic activity against HeLa and MCF-7 with primary structure activity relationship studies. To identify with the nature of interactions of these molecules, we performed molecular docking studies using the protein kinase CK2 inhibitors. The docking results afforded some valuable information for the future design of more potent inhibitors. GRAPHICAL ABSTRACT