An efficient and practical synthesis of functionalized pyridines via recyclable copper-catalyzed three-component tandem cyclization

An efficient heterogeneous copper(I)-catalyzed three-component tandem cyclization of ketoxime acetates, aldehydes, and activated methylene compounds has been developed that proceeds smoothly in DMSO at 120 °C by using an 3-(2-aminoethylamino)propyl-modified MCM-41-bound copper(I) bromide [MCM-41-2N-CuBr] as the catalyst, delivering a variety of polysubstituted pyridines in good to high yields. The heterogenized copper(I) catalyst can be readily obtained via a simple preparative procedure from commercially available and inexpensive reagents, and reused more than seven times without any apparent drop in its catalytic efficiency.