3(2h)pyridazinone, process for its preparation and anti-allergic agent containing it

Abstract From the Canadian patent

A 3(2H)pyridazinone of the formula: wherein R1 is C2-C5 alkyl; R2 is hydrogen C1-C3 alkyl, chlorine or bromine; R3 is hydrogen or C1-C4 alkyl; and each of Y1, Y2 and Y3 which may be the same or different is hydrogen, C1-C8 alkyl, C2-C8 alkenyl halogen, -(CH2)?A wherein A is substituted amino of the formula -N(R4)(R5) (wherein each of R4 and R5 which may be the same or different, is C1-C4 alkyl, or R4 and R5 together form C4-C6 alkylene), morpholino, 4-R6-piperazin-1-yl (wherein R6 is C1-C3 alkyl) or -OR7 (wherein R7 is hydrogen or C1-C3 alkyl), and ? is an integer of n to 3 -OR8 wherein R8 is hydrogen, C1-C8 alkyl C3-C5 alkenyl, benzyl or -(CH2)q-R9 wherein R9 is CO2R3 (wherein R3 is as …