o-Benzenedisulfonimide as a reusable Brّnsted acid catalyst for an efficient and facile synthesis of quinolines via Friedlنnder annulation

The synthesis of quinolines via Friedlنnder annulation was carried out in the presence of catalytic amount of o-benzenedisulfonimide as Brّnsted acid organocatalyst; the reaction conditions were mild and the yields of the target products were good. The organocatalyst was easily recovered and purified, ready to be used in further reactions.