Basic Ionic Liquid Catalyzed Cycloaddition Reactions for the Synthesis of 1, 2, 3-Triazoles

Ascribing to the superiority of possessing noteworthy physicochemical properties, ionic liquids engirdle a scientific interest in research area of chemistry as green solvent over past few decades. Being constituted entirely of ionic species, these solvents remain often as fluid at room temperature. The strength of the cation, anion or the combination of both governs the acidity or basicity of reactive ionic liquids. Due to some special properties like flexibility, non-volatility, non-corrosive, tunable property, high thermal stability and recyclability; ionic liquids offer a great potential to replace conventional solvents in chemical synthesis. Further, the use of acidic or basic ionic liquids reduces the necessity of using external acid or base along with the solvents. Therefore, implementation of these ionic liquids in chemical laboratory is widely accepted as one of the green techniques as it lessens the adverse environmental impacts.

1,2,3-triazoles are highly desired synthetic molecules in the field of chemical and pharmaceutical industries as triazole containing moieties possess potent biological activities such as anti-viral, anti-epileptic, anti-allergic, anti-microbial, anti-cancer, antituberculosis and anti-HIV properties. Its application is also extended to other areas such as organic synthesis, polymer science, material science and chemical biology. As the incorporation of basic condition favors the synthesis of these privileged classes of compounds from their starting reagents, use of basic ionic liquids as reaction media provides an alternative and greener approach for their facile construction. This chapter will discuss triazole synthesis under green conditions by following three different routes in basic ionic liquid:

• Direct azide-alkyne cycloaddition reactions affording 1,2,3-triazoles.

• Cascade synthesis of triazoles from azides and carbonyl compounds.

• One pot three component reactions leading to 1,2,3-triazoles.

Keywords: 1, 2, 3-triazoles, Anti-microbial, Atom economy, Basic ionic liquid, Click-chemistry, CuAAC, Cascade synthesis, Green Chemistry, One pot reaction, Sustainable Solvents.