Nitin B. Darvatkar

Recent developments of task-specific ionic liquids in organic synthesis

Abstract Task-specific ionic liquids (TSILs) have received increased attention over the past few years as it is possible to form any specific ionic liquid (IL) composition depending upon users need of the desired physical, chemical, and biological properties. These fascinating materials have shown promising results in various areas such as organic synthesis, catalysis, and specially recent emerging trend of use as functionalized ILs for chiral and nanoparticle synthesis. Present review gives an update of recent developments in the field of TSILs with emphasis on their applications in organic synthesis.

[bmim]HSO4: an efficient and reusable catalyst for one-pot three-component synthesis of 2,3-dihydro-4(1H)-quinazolinones

Abstract Various di- and mono-substituted quinazolinones were synthesized by one-pot condensation of isatoic anhydride, aldehyde and amine, or ammonium carbonate using [bmim]HSO4 as catalyst in aqueous medium. Water as a reaction media, recyclability of catalyst, shorter reaction time, and good yields (70–90%) are some of the salient features of the developed protocol.

Ionic Liquid–Mediated Knoevenagel Condensation of Meldrum's Acid and Aldehydes

Abstract A simple, efficient, and green protocol for Knoevenagel condensation of Meldrums acid and aldehydes in ionic liquid at room temperature without any catalyst is described. The reaction has been performed in different ionic liquids. The enhancement in the rate is observed in Brönsted acidic ionic liquid 1‐methylimidazolium trifluoroacetate [Hmim]Tfa, which furnishes quantitative yields with 4–30 min in most of the cases. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.

Ionic Liquid–Mediated Synthesis of Coumarin-3-carboxylic Acids via Knoevenagel Condensation of Meldrum's Acid with ortho-Hydroxyaryl Aldehydes

Abstract A simple, efficient, and green protocol for synthesis of coumarin-3-carboxylic acids is described via Knoevenagel condensation of Meldrums acid with ortho-hydroxyaryl aldehydes in [Hmim]Tfa ionic liquid, which was found to give better results than other ionic liquids. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.

Ionic‐Liquid‐Influenced Expeditious and Stereoselective Synthesis of Olefins

Abstract 1‐Butyl‐3‐methylimidazolium chloroaluminate, [bmim]Cl·.AlCl3 (molar fraction, N=0.67), ionic liquid has been used in combination with metallic Zn for the reductive coupling of carbonyl compounds to synthesize symmetrical olefins, with the Z‐isomer formed predominantly. The ionic liquid played a dual role of Lewis acid catalyst and solvent.

Phosphomolybdic Acid (H3Mo12O40P) as a Reusable Heterogeneous Catalyst for the Synthesis of 5-Substituted 1H-Tetrazoles via [2 + 3] Cycloaddition of Nitriles and Sodium Azide

Abstract An efficient and practical protocol for the preparation of 5-substituted 1H-tetrazole derivatives is reported using phosphomolybdic acid as an effective heterogeneous catalyst. Good yields, simple methodology, and easy workup make this protocol more attractive for the diversity-oriented synthesis of these heterocycle libraries. The catalyst can be recycled three times with good yields. GRAPHICAL ABSTRACT

Regioselective Iodination of Arenes Using Iodine/NaBO3 · 4H2O System in Ionic Liquid

Abstract A mild, efficient, and simple protocol was developed for iodination of arenes and heterocyclic compounds with molecular iodine catalyzed by sodium perborate in ionic liquid. The methodology offered iodoarenes in good to excellent yields at room temperature. The protocol proved to be highly selective, as a single isomer was formed exclusively in most of the substrates.