The present invention provides 2-aminoquinazoline derivatives represented by formula (I):
wherein R
1
and R
2
may be the same or different and each represents a hydrogen atom, substituted or unsubstituted lower alkyl, and the like;
X represents a bond or CR
7a
R
7b
wherein R
7a
and R
7b
may be the same or different and each represents a hydrogen atom, and the like;
when X is a bond, R
3
represents substituted or unsubstituted aryl or a substituted or unsubstituted aromatic heterocyclic group;
when X is CR
7a
R
7b
wherein R
7a
and R
7b
have the same meanings as defined above, respectively, R
3
represents substituted or unsubstituted lower alkoxy, substituted or unsubstituted aryl, and the like;
R
4
represents a hydrogen atom, hydroxy, substituted or unsubstituted lower alkoxy, and the like; and
R
5
represents a hydrogen atom, substituted or unsubstituted aryl, and the like, or a pharmaceutically acceptable salt thereof.