A compound of formula (I-1): ** Formula * + or a pharmaceutically acceptable salt thereof, wherein W represents a C1-6 alkyl, a C3-8 cycloalkyl, an aryl, a heteroaryl, an aralkyl, a heteroaralkyl o-N (R1) (R2)； each of R1 and R2 independently represents a hydrogen atom, a C1-6 alkyl, a C3-8 cycloalkyl, an aryl, a heteroaryl, an aralkyl or a heteroaralkyl, or R1 and R2, taken together with the nitrogen atom at which are attached, form a hetero ring containing nitrogen； alkyl, cycloalkyl, aryl, heteroaryl, aralkyl, heteroaralkyl or hetero ring containing nitrogen may be substituted with a substituent selected from a group consisting of a hydroxy, a cyano, a carboxyl, a sulfo, a halogen, a C1-6 alkyl, a halo- C1-6 alkyl, a C3-8 cycloalkyl, a C1-6 alkoxy, a C1-6 halo-alkoxy, a hydroxy-C1-6 alkyl, an amino-C1- alkyl 6, a C1-6 alkoxy-C1-6 alkyl, an amino (the amino may be mono or di-substituted with a C1-6 alkyl, an aryl or a heteroaryl), a carbamoyl (the carbamoyl may be mono or di- substituted with a C1-6 alkyl, an aryl or a heteroaryl), a sulfanyl (the sulfanyl may be mono-substituted with a C1-6 alkyl, an aryl or a heteroaryl), a C1-6 alkylsulfinyl, an arylsulfinyl, a heteroarylsulfinyl , a C1-6 alkylsulfonyl, an arylsulfonyl, a heteroarylsulfonyl, a sulfamoyl (the sulfamoyl may be mono or di-substituted with a C1-6 alkyl, an aryl or a heteroaryl), a C1-6 alkylsulfonylamino, an arylsulfonylamino, a heteroarylsulfonylamino, a C1-6 alkylcarbonyl, an arylcarbonyl, a heteroarylcarbonyl, a C1-6 alkoxycarbonyl, an aryloxycarbonyl, a heteroaryloxycarbonyl, a carbamoylamino (the carbamoylamino) di-substituted with a C1-6 alkyl, an aryl or a heteroaryl), a C1-6 alkoxycarbonylamino, an aryloxycarbonylamino, a heteroaryloxycarbonylamino, a C1-6 alkylcarbonylamino, an arylcarbonylamino, a heteroarylcarbonylamino, an aryl, a heteroaryl, an aralkyl, a heteroaralkyl, an aralkyloxy and a heteroaralkyloxy； Y1 represents formula (II-2) or formula (II-3)； ** Formula ** each of n2, n3 in
