Debasree Saha

Remarkable influence of substituent in ionic liquid in control of reaction: simple, efficient and hazardous organic solvent free procedure for the synthesis of 2-aryl benzimidazoles promoted by ionic liquid, [pmim]BF4

A simple and efficient procedure for the synthesis of 2-substituted benzimidazoles has been developed by a one-pot reaction of o-phenylenediamine with aromatic aldehydes in the presence of an ionic liquid, 1-methyl-3-pentylimidazolium tetrafluoroborate, [pmim]BF4 at room temperature in open air without any organic solvent. The ionic liquid is recycled. A remarkable influence of the substituent on the imidazolium unit of the ionic liquid on the outcome of the reaction is observed.

Metal nanoparticles as efficient catalysts for organic reactions

Pd(0) nanoparticles have been demonstrated to be very efficient catalysts for C–C bond-forming reactions. These include coupling of vicinal-diiodoalkenes and acrylic esters and nitriles leading to the stereoselective synthesis of 2-alkene-4-yn-esters and nitriles, allylation of active methylene compounds by allyl acetate, and Hiyama cross-coupling of aryliodides with arylsilanes. Cu(0) nanoparticles catalyze aryl-sulfur bond formation, accomplishing the synthesis of functionalized aryl sulfides and aryl- and vinyl dithiocarbamates. Cu nanoparticles have also been used for the chemoselective reduction of aromatic nitro compounds.

Green Recyclable Supported-Metal Catalyst for Useful Organic Transformations

One of the major challenges confronted by modern chemists is the development of sustainable chemistry to maintain environmental chastity. With this perspective in mind, heterogeneous organometallic chemistry has been intensively investigated in recent times. The advantages offered by the heterogeneous catalysts are ease of separation of product, reusability of the catalyst, improved efficiency, eco-compatibility and economic feasibility. This review focuses on the application of heterogeneous catalysis in different synthetic approaches. The review consists of six units namely, palladium mediated reactions, copper mediated reactions, ruthenium mediated reactions, rhodium mediated reactions, multimetallic catalytic systems and supported catalysts for asymmetric transformations, which cover almost all sorts of latest developments in organic transformations promoted by immobilized transition metal catalysts. The discussion not only involves the illustration of efficiency and reusability but also highlights the scope and limitations associated with the supported catalytic systems from a green chemistry standpoint.

Potential of metal nanoparticles in organic reactions

Palladium(0) nanoparticle has been used as efficient catalyst for (a) the stereoselective synthesis of (E)- and (Z)-2-alkene-4-ynoates and —nitriles by a simple reaction of vic-diiodo-(E)-alkenes with acrylic esters and nitriles and (b) for the allylation of active methylene compounds by allylacetate and its derivatives. Copper(0) nanoparticle catalyzes aryl-sulfur bond formation very efficiently. All these reactions are ligand-free.