| abstract |
The present invention provides a compound which is represented by the formulan nwherein R 4 ' is a halogen atom, R 5 is a hydrogen atom, an optionally substituted alkyl group, an acyl group, an optionally substituted hydroxy group, an optionally substituted amino group, a halogen atom, a cyano group or a nitro group, and R 15 is an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group, or a salt thereof. |