<unk> , also known as rac-13-ethyl-17α-ethynyl-19-nortestosterone or as rac-13-ethyl-17α-ethynylestr-4-en-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone. It is a racemic mixture of stereoisomers dextronorgestrel (the C13α isomer; l-norgestrel, L-norgestrel, or (+)-norgestrel) and levonorgestrel (the C13β isomer; d-norgestrel, D-norgestrel, or (–)-norgestrel), the former of which is inactive (making<unk>  exactly half as potent as levonorgestrel).<unk>  is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins. Synthesis Chemical syntheses of<unk>  have been published.
Norgestrel
Levonorgestrel
Desogestrel
Gestodene
Etonogestrel
Chloroethynylnorgestrel
5α-Dihydrolevonorgestrel
Cloxestradiol acetate