Synthesis of 1H-Quinazoline-2,4-diones from 2-Aminobenzonitriles by Fixation of Carbon Dioxide with Amidine Moiety Supported Polymer at Atmospheric Pressure

1H-Quinazoline-2,4-diones, which are key intermediates in the synthesis of medicines, were successfully synthesized from 2-aminobenzonitriles by the fixation of CO2 in the presence of a polystyrene derivative bearing amidine moiety [poly(amidine)]. A model reaction, that is, the reaction of 2-aminobenzonitrile (1a) with CO2 in the presence of N-methyltetrahydropyrimidine (MTHP) revealed that a catalytic amount of MTHP afforded 1H-quinazoline-2,4-dione (2a) quantitatively at atmospheric pressure. Several 1H-quinazoline-2,4-diones (2a-2c) were successfully synthesized from the corresponding 2-aminobenzonitriles (1a-1c) in the presence of poly (amidine). The poly(amidine) could easily be separated from the reaction mixture by filtration and reused in subsequent reactions owing to the heterogeneous system, These demonstrated that poly(amidine) is a useful heterogeneous polymer-supported reagent for the synthesis of 1H-quinazoline-2,4-diones from CO2. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 653-657, 2009