Estradiol 3-methyl ether (1, EME) is partially reduced to the 1,5-diene (2) as also occurs for the first step in the synthesis of nandrolone. Oppenauer oxidation then transforms the C17β hydroxyl group into a ketone functionality (3). This is then reacted with metal acetylide into the corresponding C17α ethynyl compound (4). Hydrolysis of the enol ether under mild conditions leads directly to (5), which appears to be noretynodrel (although Lednicer states that it is "etynodrel" in his book (which may be a synonym etynodiol); etynodrel is with a chlorine atom attached), an orally active progestin. This is the progestogen component of the first oral contraceptive to be offered for sale (i.e., Enovid). Treatment of the ethynyl enol ether with strong acid leads to norethisterone (6).