Pyridazinone derivatives and processes for preparing the same

摘要

Disclosed is a pyridazinone compound represented by the formula (I): wherein X represents hydrogen atom or the like; Y represents a single bonding arm, oxygen atom or sulfur atom; A represents a straight or branched alkylene group which may have a double bond; B represents carbonyl group or thiocarbonyl group; and R<2> represents an alkyl group having 1 to 10 carbon atoms which may be substituted or the like; or B represents sulfonyl group; and R<2> represents a lower alkenyl group or the like; R<1> represents hydrogen atom or the like; R<3> represents hydrogen atom or the like; R<4> represents hydrogen atom or the like; and R<5> represents hydrogen atom or the like, or a pharmaceutically acceptable salt thereof.