Novel sesquiterpene derivatives having progesterone receptor binding inhibitory activity and process for producing the same

Sesquiterpene derivatives, represented by the following formulae (I) and (II), having progesterone receptor binding inhibitory activity are disclosed. They can be used as therapeutic and prophylactic agents for progesterone-related diseases, for example, as a carcinostatic agent for breast cancer or ovarian cancer, a therapeutic agent for hysteromyoma, endometriosis, meningioma, or myeloma, an abortifacient, an oral contraceptive pill, or a therapeutic or prophylactic agent for osteoporosis or climacteric disturbance.; These compounds have no steroid skeleton and, hence, are considered to be advantageously free from side effect inherent in steroid such as found in conventional progesterone receptor binding inhibitors having a steroid skeleton. wherein R represents a hydrogen atom, a halogen atom, C1-C5 alkoxy, or phenylthio; R represents C1-C5 alkoxy or C2-C5 alkanoyloxy; and ---- with letters a, b, c, d, and e attached thereto represent a double bond or a single bond; R has the same meaning as R; and R represents C1-C5 alkoxy.