Cu-Catalyzed Three-Component Cascade Annulation Reaction: An Entry to Functionalized Pyridines

A concise copper-catalyzed N–O bond cleavage/C–C/C–N bond formation procedure has been described for the synthesis of multisubstituted pyridines. Various oxime acetates, activated methylene compounds, and a wide range of aldehydes bearing aryl, heteroaryl, vinyl, and trifluoromethyl groups were employed to provide the tri- or tetrasubstituted pyridines with flexible substitution patterns. Moreover, this method features inexpensive catalysts, no need for extra oxidant, and high step-enconomy, which make it pratical and attractive.