Choline chloride–ZnCl₂: Recyclable and efficient deep eutectic solvent for the [2+3] cycloaddition reaction of organic nitriles with sodium azide

Thermal azide–alkene cycloaddition reactions: straightforward multi-gram access to Δ2-1,2,3-triazolines in deep eutectic solvents

“…21 In particular, DESs have been applied to several cycloaddition reactions such as Lewis acid-catalysed Diels-Alder reactions, 22 formation of pyrrolidines from the corresponding azomethine ylides, 23 and isoxazoles from nitrile oxides. 24 From azides, either tetrazoles 25 or triazoles 26 have been prepared in DES. In many of these examples the beneficial effect of DES as reaction media was rationalised either through the Lewis acidity of one of the components, or the formation of hydrogen bonds between either of the components and the cycloaddition partners.…”

Green and Sustainable Solvents in Chemical Processes

“…To reduce the use of VOCs, DES/NADES have been explored as a potential solvent replacement for some organic syntheses. Studies have been published on the use of DES in common organic reactions such as aldol, cycloaddition, and catalysts for reactions. − Recent advances in organic synthesis are listed below. In 2016, Marset et al successfully synthesized tetrahydroisoquinolines using choline chloride:ethylene glycol in the presence of a copper catalyst and found that the reaction only proceeds in the presence of the DES .…”

One-Pot Diastereoselective Synthesis of Tetrahydroquinolines from Star Anise Oil in a Choline Chloride/Zinc Chloride Eutectic Mixture

“…The substitution of hazardous and expensive solvents, additives, and catalysts and the simplification of synthetic and purification procedures together with waste reduction are some relevant issues that have made DESs and their applications a research area of interest. These alternative solvents have demonstrated to be a versatile reaction media and/or catalyst for conducting a wide scope of chemical transformations, and several reviews devoted to this are found in the literature. , Within the recently studied reactions in DESs, the preparation of heterocyclic compounds bearing different functional groups and heteroatoms has attracted special interest because of their multiple applications in medicine and materials science. − …”