<unk> , also known as 17α-ethynyl-18-methyl-19-nortestosterone or as 17α-ethynyl-18-methylestr-4-en-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone. It is the C13β or levorotatory stereoisomer and enantiopure form of norgestrel, the C13α or dextrorotatory isomer being inactive.<unk>  is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is the parent compound of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins.<unk>  acetate and<unk>  butanoate are C17β esters of<unk> . It has a molecular weight of 312.45 g/mol and a partition coefficient (logP) of 3.8.
Levonorgestrel
Etonogestrel
Norgestrel
Desogestrel
Chloroethynylnorgestrel
Gestodene
5α-Dihydrolevonorgestrel
Norelgestromin