In recent years, considerable effort has been devoted to the search for orally-active progestational agents to substitute for the natural hormone, progesterone. The newer synthetic progestogeils ~vhich have acquired prominence because of their oral activity fall into two classes: 19-ilorsteroids such as 19-norprogesterone (1) and 17a-ethynyl-19- ilortestosterone (2) and its A5('0)-isomer (3), and derivatives of progesterone containing a 17a-acetoxy substituent (4-7). It has ...
