The ?-Valerolactone (GVL) as Innoxious Reaction Media for the Synthesis of 2-Aryl-2H-Indazoles via C-N and N-N Bond Formation under Cu(I)-Catalyzed Ligand and Base Free Conditions

An efficient method for N-arylation and N-N bond formation has been developed using an innoxious reaction medium, ?-valerolactone (GVL), as both a solvent and a ligand. The strategy involves utilizing CuI as a catalyst under conditions free of external ligands and bases. Various aldehyde and amine derivatives with different functional groups were investigated, resulting in the production of 2-aryl-2H-indazole compounds with yields ranging from 75% to 93%. This study highlights the effectiveness of GVL, a solvent derived from biomass, as a reaction medium and ligand in a multicomponent reaction.