A compound of the formula (I):
wherein
R
1
is hydrogen or lower alkyl;
R
2
is lower alkyl, etc.;
R
3
is lower alkoxy, etc.;
R
4
is hydroxy, etc.; X is O, S, etc.; Y is CH or N; Z is lower alkylene or lower alkenylene; and m is 0 or 1; or salts thereof, which are useful as a medicament.
A compound of the formula (I):
1
wherein R
1
is hydrogen or lower alkyl;
R
2
is lower alkyl, etc.;
R
3
is lower alkoxy, etc.;
R
4
is hydroxy, etc.;
X is O, S, etc.;
Y is CH or N;
Z is lower alkylene or lower alkenylene; and
m is 0 or 1; or salts thereof, which are useful as a medicament.