| abstract |
The present invention provides a compound represented by formula (1) wherein R1 is an amino group which may be substituted; R2 is a hydrogen atom or a lower alkyl group which may be substituted; X is a methyne group which may be substituted or N(O)m (m is 0 or 1); a ring A is a homo- or hetero-cycle which is substituted by a halogen atom, lower alkyl, lower alkoxy or lower alkylenedioxy; and a ring B is a homo- or hetero-cycle which may be substituted; or a salt thereof, which exhibits excellent cell differentiationinducing action and cell differentiation-inducing factor action-enhancing action, and is useful in the treatment and prevention of various nerve diseases of bone/joint diseases. |