Ziyauddin S. Qureshi

Applications of ionic liquids in organic synthesis and catalysis

In recent years, various novel and greener methodologies have been developed using ionic liquids (ILs). In these reactions, IL has played multiple roles like catalyst, solvent, and catalyst support. In some cases, it was observed that IL enables efficient catalytic reactions in comparison with conventional molecular solvents. On the other hand, although a number of catalytic reaction processes in which ILs are used have been established in industry, there were also some unexpected problems, such as unintelligible aberrance or degradation of so-called task-specific ILs occurring in reaction processes and on the pilot plant scale. Also, several urgent questions regarding the fundamental aspects of ILs particularly toxicity and greener preparation methods need to be clarified. Several industrial applications of ILs are also discussed.

An efficient and heterogeneous recyclable palladium catalyst for chemoselective conjugate reduction of α,β-unsaturated carbonyls in aqueous medium

An highly efficient PS-Pd-NHC catalytic system has been developed for chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds providing good to excellent conversion with remarkable chemoselectivity (up to 100%). The developed protocol is more advantageous due to use of HCOONa as hydrogen source, environmentally benign water as solvent and effective catalyst recyclability.

Palladium Nanoparticles Supported on Fibrous-Structured Silica Nanospheres (KCC-1): An Efficient and Selective Catalyst for the Transfer Hydrogenation of Alkenes

An efficient palladium catalyst supported on fibrous silica nanospheres (KCC‐1) has been developed for the hydrogenation of alkenes and α,β‐unsaturated carbonyl compounds, providing excellent yields of the corresponding products with remarkable chemoselectivity. Comparison (high‐resolution TEM, chemisorption) with analogous mesoporous (MCM‐41, SBA‐15) silica‐supported Pd nanocatalysts prepared under identical conditions, demonstrates the advantage of employing the fibrous KCC‐1 morphology versus traditional supports because it ensures superior accessibility of the catalytically active cores along with excellent Pd dispersion at high metal loading. This morphology ultimately leads to higher catalytic activity for the KCC‐1‐supported nanoparticles. The protocol developed for hydrogenation is advantageous and environmentally benign owing to the use of HCOOH as a source of hydrogen, water as a solvent, and because of efficient catalyst recyclability and durability. The recycled catalyst has been analyzed by XPS spectroscopy and TEM showing only minor changes in the oxidation state of Pd and in the morphology after the reaction, thus confirming the robustness of the catalyst.

Gold Nanoparticles Supported on Fibrous Silica Nanospheres (KCC‐1) as Efficient Heterogeneous Catalysts for CO Oxidation

Gold nanoparticles (Au NPs) of different sizes were supported on fibrous silica nanospheres (KCC‐1) by various methods. The size and the location of the Au NPs on the support were found to depend on the preparation method. The KCC‐1‐supported Au NPs were thoroughly characterized by using HR‐TEM, XRD, X‐ray photoelectron spectroscopy, UV, and Brunauer–Emmett–Teller surface area measurements and were applied in catalysis for the oxidation of CO. The catalytic performance is discussed in relation to the morphological properties of KCC‐1.

One-pot electrochemical synthesis of palladium nanoparticles and their application in the Suzuki reaction

A novel potential controllable, template free, electrodeposition/synthesis of palladium nanoparticles on an electrode surface as well as in the bulk electrolyte using ionic liquid as an electrolyte cum stabilizer is reported for the first time. The present method of preparation of palladium nanoparticles is advantageous as it eliminates the requirement of additional stabilizers or capping agents. The prepared palladium nanoparticles are characterized by different techniques such as TEM, SEM, EDAX and XPS analyses. These nanoparticles exhibited high catalytic activity for the Suzuki coupling reaction of unactivated halides in aqueous media with high TON.

Brønsted acidic ionic liquid: a simple, efficient and recyclable catalyst for regioselective alkylation of phenols and anti-Markovnikov addition of thiols to alkenes

A highly efficient protocol for the alkylation of phenols and anti-Markovnikov addition of thiols with various alkenes has been developed using a Bronsted acidic ionic liquid, N-methyl-2-pyrrolidone hydrogen sulfate [NMP]+HSO4−, under solvent free conditions. The developed methodology offers appreciable advantages with respect to excellent yield, short reaction time and high regioselectivity. The C–C and C–S bond formation has been achieved under metal free conditions.

Ionic Liquid : An Efficient and Recyclable Catalyst for the Synthesis of 1-Amidoalkyl-2-naphthols and 1-Carbamatoalkyl-2-naphthols Under Solvent-Free Conditions

Abstract A simple and efficient protocol for the one-pot synthesis of 1-amidoalkyl-2-naphthols and novel 1-carbamatoalkyl-2-naphthols has been described under solvent-free conditions, using N-methyl-2-pyrrolidone hydrogen sulfate as a reusable Brønsted acidic ionic liquid. This methodology has several advantages such as use of a halogen-free ionic liquid , excellent yields, short reaction time, easy workup procedure, and reusable catalyst. GRAPHICAL ABSTRACT

Polyvinylsulfonic acid as a novel Brønsted acid catalyst for the synthesis of bis(indolyl)methanes

Abstract Polyvinylsulfonic acid as a novel, biodegradable, and efficient Brønsted acid catalyst for the reaction of indoles with aldehydes to obtain bis(indolyl)methanes has been reported. The catalyst exhibited remarkable activity, recyclability, and tolerated a wide variety of functional groups providing the desired bis(indolyl)methanes in excellent yield (64–96%) at room temperature using ethanol as a solvent. The effect of different reaction parameters like solvent, temperature, catalyst doses, and recyclability were investigated for the title reaction.

SOMC-Designed Silica Supported Tungsten Oxo Imidazolin-2-iminato Methyl Precatalyst for Olefin Metathesis Reactions

Synthesis, structure, and olefin metathesis activity of a surface complex [(≡Si-O-)W(═O)(CH3)2-ImDippN] (4) (ImDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-iminato) supported on silica by a surface organometallic chemistry (SOMC) approach are reported. The reaction of N-silylated 2-iminoimidazoline with tungsten(VI) oxytetrachloride generated the tungsten oxo imidazolin-2-iminato chloride complex [ImDippNW(═O)Cl3] (2). This was grafted on partially dehydroxylated silica pretreated at 700 °C (SiO2-700) to afford a well-defined monopodal surface complex [(≡Si-O-)W(═O)Cl2-ImDippN] (3). 3 underwent alkylation by ZnMe2 to produce [(≡Si-O-)W(═O)(CH3)2-ImDippN] (4). The alkylated surface complex was thoroughly characterized by solid-state NMR, elemental microanalysis, Raman, FT-IR spectroscopies, and XAS analysis. 4 proved to be an active precatalyst for self-metathesis of terminal olefins such as propylene and 1-hexene.

Pd(OAc)2-Catalyzed Carbonylative Coupling of Aryl Iodide with Ortho-Haloamines in Water

Abstract The carbonylative cross coupling of aryl iodide with ortho-haloaniline to ortho-haloanilide using phosphine-free Pd(OAc)2 catalyst in water as a reaction medium has been studied. The present protocol facilitated the reaction of o-haloanilines with a wide variety of hindered and functionalized aryl iodides, affording good yields of the desired products. The protocol was also extended for the synthesis of benzoxazoles through cyclization of ortho-haloanilide using Cu(acac)2 catalyst. GRAPHICAL ABSTRACT