Propylene Carbonate as a Solvent in the Eco-Friendly Synthesis of Highly Substituted Imidazoles Through the Radziszewski Reaction

We have developed a simple, efficient and green method for the preparation of 2,4,5-triaryl imidazoles using propylene carbonate (PC) as an alternative solvent in the Radziszewski reaction, avoiding other organic solvents such as AcOH, MeOH, EtOH, DMSO and DMF. A wide range of 2,4,5-triaryl substituted imidazoles were synthesized. The nature of the substituents on the aromatic aldehyde had no significant effect on the reaction yield. PC offers advantages not only in the yield of the reaction but also in isolation of the product, which consists of a simple filtration followed by washes with warm water. The product was purified to a high analytical purity level by washing with hot hexane, (simple, single-step work-up). Thus, this protocol is practical and economically attractive.