In one embodiment, compounds of the following structure are described, wherein R.sub.1 to R.sub.7 are described herein. Also provided are methods for preparing these compounds and methods of contraception; treating or preventing fibroids; treating or preventing uterine leiomyomata; treating or preventing endometriosis, dysfunctional bleeding, and polycystic ovary syndrome; treating or preventing hormone-dependent carcinomas; providing hormone replacement therapy; stimulating food intake; synchronizing estrus; and treating cycle-related symptoms using the compounds described herein.