Imino Diels–Alder reaction — An efficient synthetic protocol for 2-methyl-4-substituted tetrahydroquinolines catalyzed by copper dipyridine dichloride

Abstract

For the first time, copper dipyridine dichloride (CuPy 2 Cl 2 ) is used as an efficient and reusable catalyst for the imino Diels–Alder reaction of para-substituted anilines with N-vinylpyrrolidinone, N-vinylcarbazole, and N-vinylcaprolactam in acetonitrile to afford the corresponding 2-methyl-4-substituted-1,2,3,4-tetrahydroquinoline derivatives in excellent yields with good purity. The products were characterized by FTIR, 1 H NMR, 13 C NMR, MS, and elemental analysis.