para-Toluenesulfonic Acid-Catalyzed, Ultrasound-Promoted, One-Pot, Three-Component Coupling of Aldehydes, beta-Dicarbonyls/Amides, and Electron-Rich Arenes

An ultrasound-promoted, metal-free method for the three-component coupling of aldehydes, beta-dicarbonyls/amides, and electron-rich arenes is reported here. The versatility of the method is established by employing varieties of functionally diverse components for coupling. In lieu of expensive, toxic, or specifically designed catalysts, the method presented here employs commercially available, inexpensive and non-toxic para-tolouensulfonic acid monohydrate (pTSA) as an efficient catalyst. An insight into the mechanistic pathway of the three-component coupling reaction is also provided by isolating the intermediate and subsequently converting it to the final product. The flexibility of choosing the components in the method described here allows one-pot access to a variety of relevant organic motifs.