Ultrasound assisted synthesis of various substituted heterocyclic compounds catalyzed by triflate

Quinoline and its derivatives are an important class of N-containing heterocycles; they are present in a wide variety of naturally occurring alkaloids with pharmacological properties. Indenoquinoline derivatives serve as antimalarial and anticancer drugs. In addition, acridine derivatives containing 1,4-dihydropyridine, are reported as well known compounds for their pharmacological profile in calcium channel modulations. One of the way for the synthesis of indenoquinoline compounds is, condensation of aromatic aldehydes, aromatic amines, and 1,3-cyclicdiones. Therefore in recent years , much attention has been directed toward the synthesis of indenoquinoline derivatives via the multi-component reactions in the presence of various catalysts such as p- TSA, IL, CAN, iodine. Multicomponent reactions (MCRs) are special types of synthetically useful organic reactions in which three or more different starting materials react to a final product in a one – pot procedure. On the other hand, Ultrasonic-assisted organic synthesis (UAOS) as a green synthetic approach is a powerful technique that is being used to accelerate organic reactions. Recently, rare-earth metal triflate, M(OTf)x, catalyst organic synthesis were developed as a new type of Lewis acid and were applied in many reactions. Triflates have many characteristic features such as they act as Lewis acids that can be mixed with other substance or substances without changing their chemical structure in water solvents. In this study indenoquinoline compounds have been synthesized through a one-pot condensation various substituted aryl aldehydes, 1-naphthylamine, 1,3-indanedione, in the presence of Yb/Y(OTf)3 as a catalyst under conventional method and ultrasonic irradiation. Initially, we screened various conditions for the three-component reaction with p-cyanobenzaldehyde, as a reaction. The model reaction was examined in different solvents under heating conditions. In addition, a new 1,8-dioxo-decahydroacridine has been synthesized by three –component reaction of aromatic aldehyde, ammonium acetate, and dimedone in the presence of Pr(OTf)3, triflate, as a catalyst. At the final step of this study, the structures of the obtained compounds have been clarified by spectroscopic methods such as, FTIR, 1HNMR,13CNMR,and GC/LC-MS. Keywords: Heterocyclic compounds, ultrasound, one-pot reactions, indenoquinoline, triflate