Pottabathula Srinivas

Asymmetric hydrosilylation of ketones catalyzed by magnetically recoverable and reusable copper ferrite nanoparticles.

Herein we present magnetically recoverable and reusable copper ferrite nanoparticles for asymmetric hydrosilylation of several ketones. Up to 99% enantiometric excess was obtained at room temperature using polymethylhydrosiloxane as the stoichiometric reducing agent. The copper ferrite nanoparticles were magnetically separated, and the efficiency of the catalyst remains almost unaltered up to three cycles.

N4-tetradentate dicarboxyamidate/dipyridyl palladium complexes as robust catalysts for the Heck reaction of deactivated aryl chlorides.

Structurally well defined and thermally stable Pd(II) complexes, derived from N4-tetradentate dicarboxyamide/dipyridyl ligands, were evaluated as catalysts for the Heck reactions of deactivated aryl chlorides and olefins (see scheme). The concept of using an anionic carboxyamide as an ancillary ligand for palladium demonstrated here provides a new opportunity for the development of phosphine-free transition-metal catalysis.

Thiopseudourea ligated palladium complexes: synthesis, characterization and application as catalysts for Suzuki–Miyaura, Sonogashira, Heck and Hiyama reactions

A series of new non-phosphine 1-(2-picolyl)-3-benzoylsubstituted-2-benzyl-2-thiopseudourea ligands 2a–2f have been synthesized in two steps from commercially available benzoyl chlorides. Treatment of these ligands with Pd(OAc)2 in a 1 : 1 molar ratio in dichloromethane (DCM) at room temperature provided convenient access to the corresponding N,N,O-tridentate palladium(II) complexes [Pd(OAc){ArCONHC(N(CH2Py)}SCH2C6H5] (Ar = C6H5 (3a); 4-F-C6H4 (3b); 4-Br-C6H4 (3c); 4-I-C6H4 (3d); 4-Me-C6H4 (3e); 3,4,5-(OMe)3-C6H2 (3f)) in almost quantitative yields. The new ligands and their palladium complexes were characterized by NMR, IR, ESIMS, and HRMS analysis. The molecular structure of complex 3c has been determined by X-ray single-crystal diffraction. These Pd(II) complexes have been used as catalysts for the Suzuki–Miyaura, Sonogashira, Heck and Hiyama cross-coupling reactions.

Nanocrystalline magnesium oxide-stabilized palladium(0): an efficient and reusable catalyst for synthesis of N-(2-pyridyl)indoles

A selective and efficient catalytic process has been developed for the oxidative coupling between N-aryl-2-aminopyridines and alkynes using a nanocrystalline magnesium oxide (NAP–MgO)-supported palladium nanoparticle [NAP–Mg–Pd(0)] catalyst and CuCl2 as an oxidant. The process involves the ortho C–H activation of N-aryl-2-aminopyridines to give N-pyridyl indoles in excellent yields and the true heterogeneity of the catalyst is verified by studying the recoverability and reusability for four cycles without significant loss of catalytic activity.

Synthesis of 2-Indolyl-1-nitroalkane Derivatives Using Nanocrystalline Titanium(IV) Oxide

Abstract The catalytic Friedel–Crafts alkylation of indoles with nitroalkenes to furnish 2-indolyl-1-nitroalkane derivatives at room temperature with moderate to excellent yields is reported using nanocrystalline titanium(IV) oxide (nano-TiO2) catalyst. In all cases, a single regioisomer was obtained. After completion of the reaction, the catalyst was recovered by centrifugation and activated under a nitrogen flow for 1 h at 250°C for further reuse. The nano-TiO2 can be reused for four cycles with a slight decrease of activity under the same reaction conditions.

Recent Developments in Recyclable Copper Catalyst Systems for C–N Bond Forming Cross-Coupling Reactions Using Aryl Halides and Arylboronic Acids

This review covers the recent recyclable protocols for the C–N bond forming reactions between aromatic, heterocyclic and aliphatic amines such as imidazoles, benzimidazoles, benzylamines, piperidine, pyrrole, imides, anilines, hexyl, cyclohexyl amines, and amides as coupling partners with aryl iodides, bromides, chlorides, and arylboronic acids employing copper-mediated systems. The physical properties and characterization of the catalysts and their use in organic synthesis will be outlined. Most importantly, these recyclable versions developed by many groups in the recent years are potential candidates for commercial exploitation. The effect of additives, solvents, temperature, base, the nature of aryl halides on reactivity, and recycle studies of the heterogeneous catalysts are included in this review. We believe that this information is beneficial for the people who are doing similar studies in this field. Catalyst optimization is of critical importance to catalyst development, thus the information we have included in this review contains very valuable information for the newcomers to the field. To our knowledge this is the first review that covers the title chemistry.

Efficient method for the synthesis of 1,2,3-triazole functionalized isoxazolidine derivatives by 1,3-dipolar cycloaddition of nitrones with terminal olefins

ABSTRACT 1-Phenyl-1,2,3-triazole-4-carbaldehyde 1 was treated with different N-alkyl hydroxylamine hydrochlorides 2 using NaHCO3 to obtain 1,2,3-triazole substituted N-alkyl nitrones 3a–c. The nitrones 3a–c were further reacted with different substituted olefins and furnished 2-alkyl-3-(1-phenyl-1H-1,2,3-triazol-4-yl)-5-(substituted)isoxazolidine derivatives 4a–p in high yields via 1,3-dipolar cycloaddition reaction. GRAPHICAL ABSTRACT