Pralay Das

Solid supported platinum(0) nanoparticles catalyzed chemo-selective reduction of nitroarenes to N-arylhydroxylamines

Solid supported platinum(0) (SS-Pt) nanoparticles were developed as a heterogeneous catalyst following a reduction/deposition method and characterized by SEM, TEM, EDX and XRD analysis. The SS-Pt catalyst was applied in the chemo-selective reduction of nitroarenes to N-arylhydroxylamines using hydrazine hydrate as a hydrogen source. A wide variety of reducible functional groups such as halides, carboxylic acids, esters, amides, nitriles, keto, alkenes, alkynes and N-benzyl were well tolerated under the reaction conditions. This process was further successfully employed in 10 g scale reactions. N-Arylhydroxylamines were further applied for catalyst free synthesis of azoxybenzenes. Moreover, use of PEG-400 as cheap reaction medium, additive free methodology and the recyclability of SS-Pt catalyst up to ten times without significant loss of catalytic activity evidently follow the principles of green chemistry.

Solid-supported ruthenium(0): an efficient heterogeneous catalyst for hydration of nitriles to amides under microwave irradiation

Solid-supported ruthenium(0) was synthesized by the reduction deposition method and used as a heterogeneous catalyst for the hydration of nitriles to amides under microwave irradiation. A wide range of aromatic, α,β-unsaturated and aliphatic nitriles were efficiently converted to their corresponding primary amides under milder conditions. The catalyst was found to be very stable under moisture and microwave irradiation, easily separable from the reaction mixture, to cause negligible metal contamination of the product and was recyclable up to ten times without significant loss of catalytic activity.

Supported Palladium Nanoparticle-Catalyzed Carboxylation of Aryl Halides, Alkenylsilanes, and Organoboronic Acids Employing Oxalic Acid as the C1 Source

Polystyrene-supported palladium(0) (Pd@PS) nanoparticles as a heterogeneous catalyst have been developed for caboxylation of aryl halides, alkenylsilanes, and organoboronic acids to produce the corresponding carboxylic acids with minor quantities of corresponding aldehydes using bench-stable and inexpensive oxalic acid as the C1 source under focused microwave irradiation. The close vicinity of oxalic acid to Pd@PS maintained through ionic bonding helped to produce CO2 over the catalytic surface that concurrently participated in the carboxylation reaction.

A solid supported palladium(0) nano/microparticle catalyzed ultrasound induced continuous flow technique for large scale Suzuki reactions

An ultrasound-induced continuous flow technique was developed for the solid supported palladium(0) nano/microparticle (SS-Pd) catalyzed Suzuki cross coupling reaction of haloarenes (chloro, bromo and iodo) with phenyl boronic acid on a gram scale. An externally conjugated reservoir was fitted for easy operation of the reaction in water under mild basic conditions. The SS-Pd catalyst was found to be very stable in aqueous media, easily separable and recyclable up to five runs without significant loss of activity. Furthermore, the scaling of the well known Suzuki reaction up to 5 g scale under mild ultrasonic irradiation can be of industrial interest in the future.

Oxidative “reverse-esterification” of ethanol with benzyl/alkyl alcohols or aldehydes catalyzed by supported rhodium nanoparticles

A very unusual role of polystyrene stabilized rhodium (Rh@PS) nanoparticles as a supported catalyst is described for “reverse-esterification” of ethanol with benzyl/alkyl alcohols or aldehydes. Faster and selective oxidation of ethanol to acetaldehyde and H2 under Rh@PS catalyzed conditions which restricted further oxidation of benzyl/alkyl alcohols and their in situ reaction gave the corresponding acetate esters following the dehydrogenative-coupling approach. A hitherto redox dehydrogenative-coupling of ethanol and aldehydes has also been explored for the same acetate ester synthesis under Rh@PS catalyzed conditions.

Naturally occurring himachalenes to benzocycloheptene amino vinyl bromide derivatives: as antidepressant molecules.

A new series of benzocycloheptene amino vinyl bromide derivatives (9a–9m) were synthesized from isomeric mixture of himachalenes through two-step synthesis. The unusual structure of benzocycloheptene amino vinyl bromide derivative (9a) was confirmed by NMR and X-ray crystallography analyses. The newly synthesized amino vinyl bromide derivatives of benzocycloheptene were further evaluated for their antidepressant activities. The compound 9c had shown significant reduction in the immobility period.Graphical Abstract

Cyclohexyl iodide promoted approach for coumarin analog synthesis using small scaffold.

AbstractNew chemical approaches were adopted for the synthesis of biologically important coumarins utilizing cyclohexane-1,3-dione derivatives as novel scaffold which were prepared from acetone and ethyl acrylate following our previous report. The stepwise strategies of aromatization, dehydrogenation, and demethylative cyclization were followed for coumarins synthesis from cyclohexane-1,3-dione derivatives. This work reports the first time cyclohexyl iodide was used for the demethylative cyclization reaction of

Supported palladium nanoparticles-catalyzed decarboxylative coupling approaches to aryl alkynes, indoles and pyrrolines synthesis

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