Tricyclic indole compounds having affinity for serotonin receptor

1 2 3 12 4 3 4 5 3 5 6 24 7 8 910 11 Having an affinity against serotonine receptors, compound (I) shown below is useful as a therapeutic agent against various kinds of diseases of central nervous systems; (wherein Ris hydrogen; Ris hydrogen or lower alkyl; Ris hydrogen, -COORand so on; Ris hydrogen, lower alkyl and so on, or Rand Rtaken together may form ═O or ═S; Ris hydrogen, or Rand Rtaken together may form a bond; Ris hydrogen, -COORand so on; Ris hydrogen, halogen, lower alkyl and so on; Ris hydrogen, lower alkyl, cycloalkyl and so on; R, Rand Rare each independently hydrogen, halogen, lower alkyl and so on).