| abstract |
NEW MATERIAL:The 3(2H)pyridazinone derivative of formula I [R1 is H or alkyl; R2 is H, alkyl, Cl or Br; A is NR3 (R3 is H or alkyl) or O; X is (CH2)n, CH(OR4) (n is 1-4; R4 is R3), etc.; when X is (CH2)n or single bond, B is O, S, NH, etc., and when X is CH(OR4), B is O, S, NH, OSO2, etc.; Y1-Y3 are H, alkyl, alkenyl, halogen, OR5 (R5 is R3), etc.] and its salt. EXAMPLE:4-Chloro-5-[2-(4-methoxyphenyl)ethylamino]-2-ethyl-3(2-H)-pyri dazinone. USE:It has anti-SRS-A activity and is useful as an antiallergic agent. PREPARATION:The compound of formula I can be produced e.g. by reacting the compound of formula II (Z is Cl or Br) with the compound of formula III in the presence of a dehydrohalogenation agent, reacting the product with a halogenation agent, etc., in the presence of a dehydrohalogenation agent, and reacting the result compound of formula IV (T is Cl, Br, etc.) with the compound of formula V. |