Kasiviswanadharaju Pericherla

Copper-catalyzed tandem azide-alkyne cycloaddition, Ullmann type C-N coupling, and intramolecular direct arylation.

A ligand-free copper-catalyzed tandem azide-alkyne cycloaddition (CuAAC), Ullmann-type C-N coupling, and intramolecular direct arylation has been described. The designed strategy resulted in the synthesis of a novel trazole-fused azaheterocycle framework. The reaction gave good yields (59-77%) of 1,2,3-triazole-fused imidazo[1,2-a]pyridines in a single step.

One-pot sequential C–N coupling and cross dehydrogenative couplings: synthesis of novel azole fused imidazo[1,2-a]pyridines

An efficient one-pot protocol has been developed using sequential C-N coupling and intramolecular dehydrogenative cross-couplings for the synthesis of azole fused imidazo[1,2-a]pyridine derivatives in good yields (62-78%).

Imidazolium ionic liquid-tagged palladium complex: an efficient catalyst for the Heck and Suzuki reactions in aqueous media

An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology.

Povarov-Reductive Amination Cascade to Access 6-Aminoquinolines and Anthrazolines

A new strategy is reported for the synthesis of 6-aminoquinoline derivatives via a tandem Povarov reaction, dihydroquinoline oxidation, and imine reduction. These products allow access to symmetrical as well as unsymmetrical tetraarylpyrido[2,3-g]quinolines, potentially useful organic electronics.

Oxidative Cross-Coupling of sp3- and sp2-Hybridized C–H Bonds: Vanadium-Catalyzed Aminomethylation of Imidazo[1,2-a]pyridines

The vanadium-catalyzed oxidative coupling of substituted 2-arylimidiazo[1,2-a]pyridines to N-methylmorpholine oxide, which acts as both a coupling partner and an oxidant, has been achieved. This reaction was applied to various substituted imidiazo[1,2-a]pyridine and indole substrates, resulting in yields as high as 90%. Mechanistic investigations indicate that the reaction may proceed via a Mannich-type process. This work demonstrates how oxidative aminomethylation can be used as a useful method to introduce tertiary amines into heterocycles, thus providing an alternative method for conventional Mannich-type reactions.

Synthesis of aza-fused isoquinolines through domino cross-aldol condensation and palladium-catalyzed intramolecular direct arylation.

A straightforward method has been developed for the synthesis of aroyl-substituted imidazo-/benzimidazo-fused isoquinolines. The cascade reaction proceeds via a cross-aldol condensation of 2-(1H-imidazol-1-yl/benzimidazolyl-1-yl)-1-arylethanones and 2-bromobenzaldehyde followed by palladium-catalyzed intramolecular C-H functionalization. This approach offers a simple and efficient alternative one-pot protocol for the assembly of imidazo/benzimidazo[2,1-a]isoquinolines in moderate to good yields.

One-pot, three component tandem reaction of 2-aminopyridines, acetophenones and aldehydes: synthesis of 3-aroylimidazo[1,2-a]pyridines

A facile synthesis of 3-aroylimidazo[1,2-a]pyridine derivatives has been achieved through the one-pot, three-component tandem reaction of acetophenones, arylaldehydes and 2-aminopyridines in the presence of a catalytic amount of copper(II) chloride and air as the sole oxidant. The developed one-pot method is atom-economical and utilizes readily available precursors to offer highly functionalized N-fused imidazoles in moderate to good yields (26–82%). The presented tandem process is expected to proceed via crossed aldol condensation, Michael addition, copper catalyzed oxidative cyclization and subsequent aromatization.

Synthesis and antiproliferative activities of quebecol and its analogs.

Simple and efficient synthesis of quebecol and a number of its analogs was accomplished in five steps. The synthesized compounds were evaluated for antiproliferative activities against human cervix adenocarcinoma (HeLa), human ovarian carcinoma (SK-OV-3), human colon carcinoma (HT-29), and human breast adenocarcinoma (MCF-7) cancer cell lines. Among all the compounds, 7c, 7d, 7f, and 8f exhibited antiproliferative activities against four tested cell lines with inhibition over 80% at 75 μM after 72 h, whereas, compound 7b and 7g were more selective towards MCF-7 cell line. The IC50 values for compounds 7c, 7d, and 7f were 85.1 μM, 78.7 μM, and 80.6 μM against MCF-7 cell line, respectively, showing slightly higher antiproliferative activtiy than the synthesized and isolated quebecol with an IC50 value of 104.2 μM against MCF-7.

Click chemistry inspired synthesis of piperazine-triazole derivatives and evaluation of their antimicrobial activities

AbstractA series of novel piperazine-1,2,3-triazole derivatives, which entailed the bioisosteric replacement of the imidazole moiety and hybridization of two drug scaffolds was prepared by employing the regioselective copper (I)-catalysed azide-alkyne 1,3-dipolar cycloaddition reaction. The synthesized compounds were evaluated for antibacterial activities against Gram-negative (E. Coli and P. Putida), Gram-positive S. Aureus bacteria and fungicidal activities against F. oxysporum, F. gramillarium and F. monalliforme fungi. Compound 7ac′ exhibited moderate but promising antibacterial activity against Gram-negative bacteria and fungicidal activity against F. oxysporum and F. gramillarium.