Concise Synthesis of 4-Arylquinolines via Intramolecular Cyclization of Allylamines and Ketones

The intramolecular cyclization of allylamines and ketones was achieved in the presence of potassium tert-butoxide and N, N-dimethylformamide. A series of 4-arylquinolines was prepared in good yields. The reaction could be accomplished at room temperature using only a substoichiometric amount of potassium tert-butoxide. On the other hand, the reaction of the structurally analogous allyl ethers afforded diverse products. The reaction may proceed via the rearrangement of a-aminoallyl radicals and the generation of nucleophilic enamine intermediates. This finding represents a new strategy for the synthesis of quinoline derivatives from readily available 2-(allylamino)phenyl ketones.