4-(4-chlorophenyl)-1H-2,3-benzoxazin-1-one

It acts as a key precursor, typically being converted through subsequent chemical steps (such as reduction, chlorosulfonation, and ammonolysis) into the final active pharmaceutical ingredient. 4-(4-Chlorophenyl)-1H-2,3-benzoxazin-1-one is a critical intermediate in the synthesis of the antihypertensive and diuretic drug Chlorthalidone.