Theoretical Study on Tautomerism of Quinazolinones

Proton transfer processes between various tautomers of quinazolinones were investigated by using density functional theory method at B3LYP/6-311+G(d,p) level.The two possible reaction pathways,i.e.intramolecular proton transfer and water-assisted proton transfer,were investigated.The calculated results show that the latter pathway has lower activation energies than the former pathway involving intramolecular tautomeric reaction,because of the formation of hydrogen-bonded complexes in water-assisted proton transfer.This implies that the hydrogen bonds formed in the complexes play an important role in water-assisted proton transfer.