Synthesis, characterization and organocatalytic activity of novel chiral (ammoniummethyl)pyrrolidine-derived deep eutectic solvents

The present investigation centers on synthesizing, characterizing, and exploring the organocatalytic potential of a novel series of chiral deep eutectic solvents based on chiral (ammoniummethyl)pyrrolidine derivatives 1-3. Using the theoretical solid-liquid equilibrium curves, we have been able to identify three chiral deep eutectic solvents (CDESs) that have been thermally and structurally characterized and used as reaction medium in the conjugate addition of cyclohexanone to trans-beta-nitrostyrene. Among these chiral deep eutectic solvents, the mixture 2/EG: 1/3, where a chiral choline bromide surrogate is employed as the HBA, has shown good organocatalytic activity and recyclability in the studied model organocatalyzed process. Notably, this CDES exhibited higher activity and selectivity compared to organocatalyst 2, and at the same level as that exhibited by the 2/TFA catalyst under neat conditions.