K. Harsha Vardhan Reddy

Nano copper oxide catalyzed synthesis of symmetrical diaryl sulfides under ligand free conditions.

Summary Potassium thiocyanate acts as an efficient sulfur surrogate in C–S cross-coupling reactions mediated by recyclable copper oxide nanoparticles under ligand free conditions. This protocol avoids foul smelling thiols, for the synthesis of a variety of symmetrical diaryl sulfides, via the cross-coupling of different aryl halides with potassium thiocyanate, affording corresponding products in moderate to excellent yields.

Recyclable Ru/C catalyzed oxidative cyanation of tertiary amines with TBHP

The recyclable Ru/C catalyzed oxidative α-cyanation of tertiary amines with ethyl cyanoformate by using TBHP as an oxidant under ambient conditions has been developed. Utilizing this protocol, α-aminonitrile derivatives were synthesized in good to excellent yields with high selectivity. The cyanide source (ethyl cyanoformate) employed herein was relatively cheap and less toxic, which would be beneficial. The catalyst was also inexpensive and commercially available as well as recyclable up to four cycles, without significant loss of its catalytic activity.

Recent Developments in the Synthesis of Quinoxaline Derivatives by Green Synthetic Approaches

Introduction .....................................................................................2 I. Using Recyclable Catalysts................................................................3 A. Acid-catalyzed Reactions.......................................................................... 3 1. Sulfamic Acid-MeOH................................................................................ 3 2. Silica-supported Perchloric Acid................................................................ 4 3. Silica-bonded S-Sulfonic Acid ................................................................... 5 4. Iron-exchanged Molybdophosphoric Acid................................................... 5 B. Metal/metal Salt-catalyzed Reactions........................................................ 6 1. Ni-nano Particles ..................................................................................... 6 2. CuO Nano Particles.................................................................................. 7 3. Manganese Octahedral Molecular Sieves ................................................... 8 4. Silica-supported Antimony (III) Chloride.................................................... 8 5. ZnO-β Zeolite .......................................................................................... 9 6. PdCl2/Cu2Cl2 in PEG..............................................................................10 7. Ruthenium-on-charcoal ...........................................................................10 8. Zirconium (IV) Oxide Chloride Octahydrate ..............................................11 C. Other Recyclable Catalysts ......................................................................12 1. 1-(n-Butyl)imidazolium Tetrafluoroborate..................................................12 2. β-Cyclodextrin........................................................................................12 3. Hypervalent Iodine(III) Sulfonate-PEG 400...............................................13 4. Amberlyst-15 ..........................................................................................14 II. Using Microwave Energy ................................................................ 14 III. In Aqueous Media........................................................................... 19 1. Using Ceric(IV) Ammonium Nitrate ..........................................................19 2. Using Trimethylsilyl Chloride...................................................................20 3. Using N-Bromosuccinimide......................................................................21 IV. At Room Temperature .................................................................... 22 V. Conclusion...................................................................................... 25 References ...................................................................................... 25

Synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles catalyzed by copper ferrite nanoparticles in tap water using click chemistry

A novel one pot synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles has been developed by using CuFe2O4 magnetic nanoparticles. This methodology involves additive free, easily recyclable catalyst in water medium and avoids the handling of organic azides as they are generated in situ.

Ru/C: a simple heterogeneous catalyst for the amination of azoles under ligand free conditions

A ligand free Ru/C-catalyzed amination of 2-halo azoles with a broad scope of aminating reagents has been developed. A variety of 2-aminoazole derivatives were synthesized in moderate to good yields by utilizing this protocol. The methodology is operationally simple and not sensitive to air and moisture. It provides potentially useful products by using an inexpensive and recyclable catalytic system under ligand free conditions without significant loss of its catalytic activity up to four cycles.

A novel one pot four-component reaction for the efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate and trifluoromethylated spiro[indole-3,4′-pyrano[2,3-c]pyrazole] derivatives using recyclable PEG-400

A novel, simple and efficient synthetic protocol has been developed for the synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate and trifluoromethylated spiro[indole-3,4′-pyrano[2,3-c]pyrazole] derivatives via a one pot, four-component reaction using recyclable polyethylene glycol (PEG-400). This new protocol produces novel spiro pyranopyrazole derivatives in good to excellent yields, with operational simplicity and recycling of PEG-400. The remarkable features of this methodology are high yields, an easy work-up process, and a greener method that avoids toxic catalyst and hazardous solvents.

Ru-Catalyzed highly site-selective C–H bond arylation of 9-(pyrimidin-2-yl)-9H-carbazole

We describe here an efficient ruthenium-catalyzed C–H bond ortho-arylation of 9-(pyrimidin-2-yl)-9H-carbazole by using boronic acids. This methodology exhibits excellent and high site-selectivity, functional group tolerance and was found to give the desired product in moderate to good yields.