Reaction of electron rich alkenes with anilines and formaldehyde: Syntheses of tetrahydroquinolines

Article abstract of DOI:10.1016/0040-4020(95)00269-E

A one-pot synthesis has been established of tetrahydroquinolines based upon reaction of aromatic amines and formaldehyde with electron rich alkenes such as styrene, α-methylstyrene, 1-phenylcyclohexene and 3,4-dihydro-2H-pyran. The isolation of alcohols as additional products from reactions conducted in acetonitrile containing trifluoroacetic acid, and the demonstration that these alcohols reacted further under similar reaction conditions to give efficiently cyclised products indicates that the cyclisations reported in this paper are not concerted. The importance is discussed of similar multi-step processes in the catalysed addition of electron rich alkenes to preformed imines.