Abstract:
A process for prepg. pyrazolone dervis. of formula (I) comprises: (a) reacting halogen derivs. of formula (II) with primary amine of formula R4-NH2 in org. solvent(i.e. water, MeOH, EtOH) for 10 hr at 10-30 deg. C; (b) reacting with secondary haloketo cpd. in org. solvent i.e. benzene, toluene, dioxane in basic media i.e. NaHCO3, NaOH, triethylamine at 20-120 deg. C; and (c) reacting with hydrazine of formula R5NH-NH2 in org. solvent i.e. diethyleneglycole, THF in basic media i.e. KHCO3, NaOH. In the formulas, R1=isopropyl; R4=Me; R5=H or methanesulfonyl; X=Cl, Br or I. (I) are useful as an antipyretic analgesic.