DES-Type Interactions To Promote Solvent-Free and Metal-Free Reactions between Nitrogen-Containing Heterocycles and Allylic Alcohols

Abstract

Nitrogen-containing heterocycles are of great interest to organic chemists since they are present in a wide array of bioactive molecules. The use of allylic alcohols to carry out the allylation of heterocycles has been described as a sustainable alternative for this type of functionalization. Among the plethora of methodologies described, the use of metals, solvents, or hazardous reagents is ubiquitous. The protocol described in this work has provided a solventless and metal-free alternative, being mediated by the easy-to-synthesise and reusable 1,3-bis(carboxymethyl)imidazolium chloride. The protocol has resulted compatible with several nitrogen-containing heterocycles (i.e. indole, pyrazole, triazole, tetrazole, carbazole, indazole, and benzotriazole) and allylic alcohols, providing the allylated-heterocycles with up to quantitative yield, being possible to perform the reaction in preparative scale.Based on various green metrics (atom economy, stoichiometric factor, reaction mass efficiency, materials recovery parameter, E-factor, and EcoScale), the overall greenness significance of the methodology has been established.