Radical cation salts induced domino reaction of anilines with enol ethers：Synthesis of 1,2,3,4-tetrahydroquinoline derivatives

A domino reaction of anilines with cyclic and acyclic enol ethers induced by catalytic amounts of TBPA~（·＋）（5 mol%） was investigated and a series of 2,4-disubstituted-1,2,3,4-tetrahydroquinolines were synthesized.Different from cyclic enol ethers, when acyclic enol ethers were used in the reaction,they serve as surrogates of acetaldehyde,producing a series of 2-methyl-4- anilino-1,2,3,4-tetrahydroquinolines.A single electron transfer mechanism was proposed to rationalize the products formation.