PPA-SiO_2 as a Heterogeneous Catalyst for Efficient Synthesis of 2-Substituted-1,2,3,4-tetrahydro-4-quinazolinones under Solvent-free Conditions

Silica‐supported polyphosphoric acid (PPA‐SiO₂) catalyzed efficiently the reaction of anthranilamide with aryl aldehydes or ketones under solvent‐free conditions to afford the corresponding 1,2,3,4‐tetrahydro‐4‐quinazolinone derivatives. This work consistently has the advantages of excellent yields, short reaction time, simple experimental and work‐up procedures. The heterogeneous catalyst could be recovered and recycled for several times without any loss of its activity.