Patent ID: 8748452

Claim:
An indolizine derivative represented by the formula (I): wherein ring U represents aryl or heteroaryl; R 1 represents a halogen atom, a hydroxy group, nitro, amino or C 1-6 alkyl which may be substituted by a fluorine atom; R 2 represents any of the following (1) to (7): (1) a halogen atom; (2) a hydroxy group; (3) amino; (4) carbamoyl; (5) cyano; (6) carboxy; (7) C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 alkoxy, mono(di) C 1-6 alkylamino, C 2-7 acyl, C 2-7 acylamino, mono(di)C 1-6 alkylcarbamoyl, C 1-6 alkylsulfonyl, C 1-6 alkylsulfonylamino, mono(di)C 1-6 alkylsulfamoyl, C 1-6 alkylthio, C 2-6 alkenyl C 1-6 alkoxy, C 3-8 cycloalkyl, 3 to 8-membered heterocycloalkyl, C 5-8 cycloalkenyl, 5 to 8-membered heterocycloalkenyl, C 3-8 cycloalkyloxy, C 3-8 cycloalkylamino, C 3-8 cycloalkyl C 1-6 alkyl, C 3-8 cycloalkyl C 1-6 alkoxy, C 3-8 cycloalkyl C 1-6 alkylamino, aryl, heteroaryl, aryloxy, arylamino, arylcarbonyl, arylcarbonylamino, arylC 1-6 alkoxy, heteroaryloxy, heteroarylamino, heteroarylcarbonyl or heteroarylcarbonylamino each of which may have any group selected from substituent group α; m represents an integral number from 0 to 2 , and when m is 2, these R 1 are optionally different from each other; n represents an integral number from 0 to 3, and when n is 2 or 3, these R 2 are optionally different from each other; and when two R 2 bound to the neighboring atoms in the indolizine ring exist and independently represent a group selected from the group consisting of C 1-6 alkyl which may be substituted by a fluorine atom and C 1-6 alkoxy which may be substituted by a fluorine atom, these two R 2 optionally form a 5 to 8-membered ring together with the binding atoms in the indolizine ring; R 3 represents a hydrogen atom, a chlorine atom or a fluorine atom; and substituent group α consists of a fluorine atom, a chlorine atom, a hydroxy group, amino, carboxy, carbamoyl, cyano, C 1-6 alkyl, C 1-6 alkoxy and mono(di)C 1-6 alkylamino, or a pharmaceutically acceptable salt thereof.