|
In this paper, we carefully studied the domino reaction of N-vinyllactams, enol ethers and anilines induced by radical cation salts. A series of 1,2,3,4-tetrahydroquinoline derivatives were synthesized, giving the following results:1. A tandem cyclization of imines with N-vinyllactams induced by TBPA+. was investigated, producing a series of 2-methyl-4-anilino-1,2,3,4-tetrahydroquinolines via a domino process in which N-vinyllactams serve as acetaldehyde surrogate. A single electron transfer mechanism was proposed to rationalize the formation of the products.2. 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 based on such process. Different from cyclic enol ethers, when acyclic enol ethers were used in the reaction, they served 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 formation of the products.
|