Intramolecular cyclization of aromatic imines: an approach to tetrahydrochromano[4,3-b]quinolines

A synthesis of polysubstituted tetrahydrochromano[4,3-b]quinolines is described. These compounds have been prepared by the reaction of anilines with derivatives of salicylic aldehyde containing electron-rich olefin substituents. In the described acid-mediated intramolecular [4+2] cycloaddition reaction, the targeted products are isolated as a 1:1 mixture of diastereomers in excellent yields and purities.