4-(4-Quinazolinylthio)-butan-2-one and 3-(4-quinazolinylthio) propiophenone (4, R = CH 3, C 6H 5) with POCl 3 give 3-(3-oxobutyl)-4(3 H )-quinazolone and 3-(2-benzoylethyl)-4(3H)-quinazolone (7, R = CH 3, C 6H 5, X = O) via S → N rearrangement followed by ▪ conversion. Non-protic heterocyclic thioamides undergo similar oxidation.