A green, solvent-free one-pot synthesis of disubstituted quinolines via A3-coupling using 1 mol% FeCl3.
Quinoline derivatives are important compounds due to their broad range of applications in medicinal, synthetic and industrial chemistry. However, current synthetic techniques such as the classical Skraup, Döebner-Miller, Friedländer and Pfitzinger reactions have numerous drawbacks such as the use of expensive reagents/catalysts, strong acidic conditions, long reaction times, high temperatures and the use of environmentally unfriendly solvents. As a result, the development of new synthetic routes to access quinoline derivatives is vital. One such approach is the coupling between an aldehyde, amine and alkyne, known as A3-coupling, which results in the formation of propargylamine, which has been well documented in the literature. The synthesized propargylamines have multiple reaction sites and in the presence of a Lewis acid catalyst results in the formation of quinoline derivatives.