Patent ID: 7754743

Claim:
A compound represented by the following formula (I): or a pharmaceutically acceptable salt thereof, wherein: X 1 represents oxygen, sulfur or NH, X 2 represents oxygen, sulfur or CH 2 , R 1 represents 1 or 2 substituents optionally present on Ring A which are selected from the group consisting of alkylsulfonyl, alkanoyl, lower alkyl, hydroxyalkyl, hydroxy, alkylcarbamoyl, alkylsulfamoyl, dialkylsulfamoyl, alkylthio, alkoxy, dialkylcarbamoyl, alkoxycarbonylamino, alkoxycarbonyl, halogen atoms, alkanoylaminoalkyl, alkoxycarbonylaminoalkyl, alkylsulfonylaminoalkyl, cyano and trifluoromethyl, R 2 represents: a C3-7 cyclic alkyl group, wherein one of the constituent carbon atoms of the ring, except for the carbon atom that is bonded to X 2 , is optionally replaced with oxygen, NH, N-alkanoyl or CONH); or a straight-chain or branched lower alkyl group or a lower alkenyl group, optionally having a substituent selected from the group consisting of halo, carboxyl, alkoxycarbonyl, hydroxyl; amino which may be further substituted with 1 or 2 alkanoyl or lower alkyl groups, alkoxy and N-alkylcarbamoyl, R 3 represents 1 or 2 substituents optionally present on Ring B which are selected from the group consisting of lower alkyl; alkoxy; alkylamino; lower dialkylamino; halo; trifluoromethyl; hydroxyalkyl, wherein the hydrogen of the hydroxy in the hydroxyalkyl group may be substituted with lower alkyl; aminoalkyl; alkanoyl; carboxyl; alkoxycarbonyl and cyano; formula (II): represents a pyridyl ring optionally having 1 or 2 substituents represented by R 1 above, and formula (III): represents thiazolyl.