2-Hydroxyethylammonium formate acts as a task-specific ionic liquid (TSIL) for the Knoevenagel condensation of carbonyl compounds with rhodanine to afford arylalkylidene rhodanines under solvent-free conditions and in good-to-excellent yields. Additionally, compared with those in organic solvents, the yields obtained in the presence of our ionic liquid (IL) were significantly increased. The detailed mechanism of the catalytic effect of TSIL is also reported for the first time.
Efficient and green synthesis of 4H-pyrans and 4H-pyrano[2,3-c] pyrazoles catalyzed by task-specific ionic liquid [bmim]OH under solvent-free conditions