Abstract
A series of 2-pyridyl-3-phenyl-4 (3H)-quinazolinone and the anthranilate was reacted with phosphorus pentasulfide to give the corresponding 4 (3H)-quinazolinethiones, which were oxidized with hydrogen peroxide to afford readily the above 4 (3H)-quinazolinones. The hydrogen peroxide oxidation of them in trifluoroacetic acid gave the 1, 1'-dioxide and that in acetic acid gave the 1'-oxide. The nuclear magnetic resonance spectra of oxidation products were compared. It was found that some 4 (3H)-quinazolinethiones (Vc, VIa) were effective against several kinds of gram-positive bacteria, while exchange of the carbonyl group of 4 (3H)-quinazolinone by thione resulted in a loss of action for central nervous system.
