A Facile Synthesis of Benzo[h]quinolines via Silica‐TsOH‐P2O5 Promoted Condensation of 1‐Naphthylamines with 1,3‐Diketones under Solvent Free Conditions

A facile synthesis of benzoh ]quinolines has been developed via improved Combes reaction. A combination of silica gel, p ‐toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1‐naphthylamines with 1,3‐diketones under solvent free conditions. In this case, silica gel was used as reaction media, p ‐toluenesulfonic acid and phosphorus pentoxide were acted as catalyst and dehydrating agent, respectively.