Nano-SnO2 : An efficient catalyst for Multi-component synthesis of pyrimido[4,5-b] quinolines

Multi-component reactions (MCRs) by virtue of their convergence, productivity, ease ofexecution and generally high yields of products have attracted considerable attention fromthe point of view of combinatorial chemistry [1،2]. On the other hand pyrimido[4,5-b]quinolines are important compounds because of their biological properties which areknown to depend mainly on the nature and position of the substituent [3]. Quinolinederivatives display a broad range of biological activities such as anti-malarial [4], antitumor[5] and anti-bacterial [6]. Thus, considerable attention has been focused on thedevelopment of new methodologies to synthesize many kinds of pyridoquinoline systems. Ar = C6H5, 4-FC6H4, 4-BrC6H4, 4-MeC6H4, 4-MeOC6H4 Multi-component condensation of 1,3-cyclohexadien, aromatic aldehydes, and 6-amino-2-(ethylthio)pyrimidin-4(3H)-one were used for the synthesis of new derivatives ofpyrimido[4,5-b]quinolines under ultrasounic irradiations. This novel method furnished thedesired products in short reaction times (5-15 min) and excellent yields (85-90%).