PPA-SiO2 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.