Saurav Bhardwaj

Magnetic nanoparticles catalyzed synthesis of diverse N -Heterocycles

A large library of diversified compounds (pyrano [2,3-d]pyrimidines, pyrido[2,3-d] pyrimidines and a variety of spirooxindoles) were synthesized through a very efficient, economical and environmentally benign process utilizing magnetic nanoparticles. Ease of recovery using an external magnetic field is an additional ecofriendly attribute of this catalytic system. Most of the compounds are new; therefore, could be further explored for their pharmaceutical application. Moreover, column chromatography and recrystallisation of the products is not required as the crude products are already highly pure and hence can be used for target oriented synthesis on a wide scale.

Cu Nanoparticles in PEG: A New Recyclable Catalytic System for N‐Arylation of Amines with Aryl Halides

A new protocol for the N‐arylation of aryl halides with anilines using Cu nanoparticles in polyethylene glycol (PEG) as an efficient and reusable catalytic system has been developed. The reaction did not require any cocatalyst. Various solvents were screened, and PEG400 provided the best results. The studies showed that the mechanism of catalytic action is dependent on the size of the nanoparticles. The Cu nanoparticles and PEG were recyclable and retained their activity. This newly developed protocol was also found to be suitable for the cross coupling of NH heterocycles with iodobenzene. The present methodology offers several advantages, such as excellent yields, short reaction times, and milder reaction conditions.

Aqua mediated synthesis of 2-amino-6-benzothiazol-2-ylsulfanyl-chromenes and its in vitro study, explanation of the structure–activity relationships (SARs) as antibacterial agent

Multi-component reaction (MCR) involves coupling of p-bromophenol with 2-Benzothiazolethiol, malononitrile and substituted aldehydes in aqueous K(2)CO(3) as green base to synthesize 2-amino-6-benzothiazol-2-ylsulfanyl-chromenes. This multi-component reaction thus offers a higher yield and versatility in the preparation of densely functionalized oxygen heterocycles. The newly synthesized compounds were screened for their antibacterial activities against positive and gram negative pathogenic strains to bacteria. SAR analysis was performed to explore comprehensive structure-activity relationships and a statistically reliable model to explain their antibacterial activities.

C-Arylation reactions catalyzed by CuO-nanoparticles under ligand free conditions

Summary CuO-nanoparticles were found to be an excellent heterogeneous catalyst for C-arylation of active methylene compounds using various aryl halides. The products were obtained in good to excellent yield. The catalyst can be recovered and reused for four cycles with almost no loss in activity.

Application of mobilized Cu-nanoparticles as heterogeneous catalyst for the synthesis of α-amino phosphonatesviaA2-P coupling

Cu-nanoparticles were synthesized and utilized as an efficient, novel and recyclable catalyst for a multi-component coupling reaction using aldehyde, amine and diethyl phosphite. This method provides a wide range of substrate applicability and devoid of co-catalyst/heavy metals with an excellent yield of bioactive α-amino phosphonates. Besides this, catalyst could be recovered and reused up to four runs with almost consistent activity.

Transformation of Amines to Oximes Using Heterogeneous Nanocrystalline Titanium(IV) Oxide as a Green Catalyst

Abstract The oxidation of amines into corresponding oximes has been described using heterogeneous nanocrystalline titanium(IV) oxide as catalyst and H2O2 as oxidizing agent in quantitative yields. Both aromatics and aliphatic amines undergo oxidation. Besides this, nanocrystalline TiO2 was recovered and used for further reactions. Hence our present protocol is economical and clean and uses green reagent, solvent, and catalyst.

Lipase-catalyzed transformations using poly(ethylene glycol) as solvent

Abstract Candida antarctica lipase catalyzes a number of elementary reactions like alcoholysis, ammoniolysis and aminolysis in poly(ethylene glycol) (PEG) media. Reaction rates were comparable to or better than those observed in conventional organic reaction media and ionic liquids. It is envisaged that PEGs could have added benefits for performing biotransformations with highly polar substrates, which are sparingly soluble in common organic solvents.

Solvent-free synthesis of polyfunctional tetrahydropyrimidines promoted by recyclable ionic liquid

The synthesis of nitrogen containing heterocyclic compounds from diethyl ester, formaldehyde, and various aromatic/aliphatic amines via a simple and efficient one-pot multicomponent reaction in ionic liquid is described. The catalyst can be recycled at least three times without obvious loss in catalytic activity.Graphical Abstract

A green oxidation protocol for the conversion of secondary alcohols into ketones using heterogeneous nanocrystalline titanium (IV) oxide in polyethylene glycol

Abstract The oxidation of secondary alcohols into corresponding ketones has been described using heterogeneous nanocrystalline TiO2 as catalyst at a moderate temperature with quantitative yields. Use of H2O2 instead of O2 (g) is the main feature of our methodology since maintenance of PO2 (g) at elevated temperature is not easy. Besides, this catalyst could be recovered and reused for further reactions with consistent activity. Hence, our present protocol is economical and throughout clean consisting of green reagent, solvent, and catalyst.