A compound pf general formula (I):
1
wherein, for example,
X
1
and X
2
independently represent a hydrogen atom.
R
a
represents a hydrogen atom or a protecting group for a hydroxyl group.
R
b
and R
c
form an optionally protected —(C═O)— together with the 3-position carbon atom attached to R
b
and R
c
, and
the broken line forms a single bond or double bond together with the solid line,
or a pharmaceutically acceptable salt of the compound or a prodrug thereof.
A compound of general formula (I):
wherein, for example,
X1 and X2 independently represent a hydrogen atom,
Ra represents a hydrogen atom or a protecting group for a hydroxyl group,
Rb and Rc form an optionally protected -(C=O)- together with the 3-position carbon atom attached to Rb and Rc, and
the broken line forms a single bond or a double bond together with the solid line,
or a pharmaceutically acceptable salt of the compound or a prodrug thereof.