Abstract Cyclization kinetics of N-benzoyl-N'-(1, 2-dimethyl-3-oxo-1-butenyl) thiourea have been studied in aqueous and methanolic solutions of acids and bases. In all cases the cyclization product is 4, 5, 6-trimethyl-2, 5-dihydro-2-thioxopyrimidine or its protonated or deprotonated forms. In dilute methanolic and aqueous hydrochloric acid the substrate reacts in its monoprotonated form. The cyclization in basic media is catalyzed by methoxide or ...
