Facile Synthesis of Tetrahydroquinolines and Julolidines through Multicomponent Reaction

Aldehydes, anilines and enol ethers react in trifluoro­ethanol (TFE) through an aza-Diels-Alder reaction (Povarov reaction) to afford the corresponding substituted tetrahydroquinolines. This reaction occurs, without any catalyst, under sequential three-component conditions, allowing thus the use of aliphatic aldehydes. In the presence of formaldehyde and an excess of dienophile, the product undergoes a second Povarov reaction affording new ­julolidine derivatives.