Dharminder Sharma

Copper Promoted C-N and C-O Type Cross-Coupling Reactions

Aryl amines and ethers are very important structural motifs of numerous biologically active natural products, important phar- maceutical compounds, polymers in the material science industries and widely used as drugs, dyes, and other fine chemicals. Several studies have earlier been attempted but transition metal mediated protocols have proven more successful results. Conventional Ullmann condensation with copper in the form of metal, alloy or Cu(I)/Cu(II) salt showed major drawbacks such as requirement of high tempera- ture sensitivity to catalyst-type and low to moderate yield. In recent years, copper promoted conventional Ullmann condensation reactions have been improved a lot under ligand and ligand free conditions with excellent conversion. An important Ullmann type coupling, where aryl boronic acids are used as arylating agents instead of aryl halides has recently attracted much attention of chemist. Because of the importance of aryl amines and ethers in various fields of chemistry writing a review in this relevant area is of significant interest. This article will review the applications of copper-promoted C-N and C-O bond formation reactions focused on achievements during the periods from 2000-2008.

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.

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

Solid Supported Palladium(0) Nanoparticles: An Efficient Heterogeneous Catalyst for Regioselective Hydrosilylation of Alkynes and Suzuki Coupling of β-Arylvinyl Iodides

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Molecular associations in binary mixture of pyridine and nitrobenzene in benzene solution using microwave absorption data

β,β-diaryl acrylates for 4-arylcoumarins synthesis. Graphical abstract

Ethyl 3-(2,4-dioxocyclohexyl)propanoate as a novel precursor for N-substituted 4,4a,5,6-tetrahydroquinoline-2,7(1H,3H)-diones and their corresponding 3,4-dihydro-7-hydroxyquinolin-2(1H)-ones and 7-hydroxyquinolin-2(1H)-ones synthesis.

Novel classes of β-enaminoesters were synthesized using our newly described ethyl-3-(2,4-dioxocyclohexyl)propanoate molecule (1) under solvent and catalyst free microwave assisted conditions. No work-up procedure, milder reaction conditions, wide substrate scope and high yields add extra importance to this method and open up the scope for acridinediones as well as peptidomimetic molecule synthesis.

Solid supported Pd(0): an efficient recyclable heterogeneous catalyst for chemoselective reduction of nitroarenes ☆

The solid supported palladium(0) nanoparticles (NPs) were found as an active heterogeneous catalyst for regioselective hydrosilylation of alkynes with organosilanes in the presence of NaI as additive. Aliphatic as well as aromatic terminal/substituted alkynes with both electron releasing and withdrawing functionalities similarly participated in the hydrosilylation to produce regioselective β-isomers of vinylsilanes under mild reaction conditions. Reducible functional groups such as nitrile, ester, halide, alkene and alkyne were also found to be tolerated under this condition. Furthermore, the triethylsilylstyrene was applied for consecutive iododesilylation followed by Suzuki coupling reaction to produce stilbenes. The air/moisture stable SS–Pd catalyst was recycled for hydrosilylation reaction up to ten runs without significant loss of its catalytic activity.Graphical AbstractSolid Supported Palladium(0) Nanoparticles: An Efficient Heterogeneous Catalyst for Regioselective Hydrosilylation of Alkynes and Suzuki Coupling of β-Arylvinyl Iodides

Solid-supported palladium nano and microparticles: an efficient heterogeneous catalyst for ligand-free Suzuki–Miyaura cross coupling reaction☆

Abstract The dielectric permittivity (ε′) and dielectric loss (ε′′) for dilute solutions of pyridine (C5H5N) in benzene solution has been measured at 9.875 GHz at different temperatures (25, 30, 35 and 40 °C) by using standard microwave techniques. Following the single frequency concentration variational method, the dielectric relaxation time (τ) and dipole moment (μ) at various temperatures have been calculated. It is found that dielectric relaxation process can be treated as the rate process, just like the viscous flow. Based on the above studies, monomer structure of pyridine in benzene has been inferred. The presence of solute–solvent associations in benzene solution has been proposed. Energy parameters (ΔHε, ΔFε, ΔSε) for dielectric relaxation process of pyridine in benzene at different temperature (25, 30, 35 and 40 °C) have been calculated and compared with the corresponding energy parameters (ΔHη, ΔFη, ΔSη) for the viscous flow.