It is intended to provide a tryptophan derivative that activates osteoblasts and to provide a therapeutic drug for osteoporosis and an osteoblast activator using this tryptophan derivative.
This invention relates to a compound represented by the following formula (I) or a salt thereof:
wherein X represents a halogen atom; R
1
represents a hydrogen atom, substituted or unsubstituted C
1-6
alkyl group, substituted or unsubstituted C
2-6
alkenyl group, substituted or unsubstituted C
2-6
alkynyl group, substituted or unsubstituted aromatic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted acyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted C
1-6
alkylsulfonyl group, substituted or unsubstituted C
2-7
alkoxycarbonyl group, or hydroxyl group; R
2
represents a substituted or unsubstituted C
1-21
alkyl group; R
3
, R
5
, and R
6
are the same or different and represent a hydrogen atom or halogen atom; R
4
represents a hydrogen atom or substituted or unsubstituted C
1-6
alkyl group; and R
7
represents a hydrogen atom or substituted or unsubstituted C
1-21
hydrocarbon group, and to a therapeutic drug for osteoporosis and an osteoblast activator comprising the compound or a salt thereof.