Steroids<unk> is a naturally occurring pregnane steroid and is also known as pregn-4-ene-3,20-dione. It has a double bond (4-ene) between the C4 and C5 positions and two ketone groups (3,20-dione), one at the C3 position and the other at the C20 position. Due to its pregnane core and C4(5) double bond,<unk> is often abbreviated as P4. It is contrasted with pregnenolone, which has a C5(6) double bond and is often abbreviated as P5. Derivatives A large number of progestins, or synthetic progestogens, have been derived from<unk>  They can be categorized into several structural groups, including derivatives of retroprogesterone, 17α-hydroxyprogesterone, 17α-methylprogesterone, and 19-norprogesterone, with a respective example from each group including dydrogesterone, medroxyprogesterone acetate, medrogestone, and promegestone. The<unk> ethers quingestrone<unk> 3-cyclopentyl enol ether) and<unk> 3-acetyl enol ether are among the only examples that do not belong to any of these groups. Another major group of progestins, the 19-nortestosterone derivatives, exemplified by norethisterone (norethindrone) and levonorgestrel, are not derived from<unk> but rather from testosterone. A variety of synthetic inhibitory neurosteroids have been derived from<unk> and its neurosteroid metabolites, allopregnanolone and pregnanolone. Examples include alfadolone, alfaxolone, ganaxolone, hydroxydione, minaxolone, and renanolone. In addition, C3 and C20 conjugates of<unk>  such as<unk> carboxymethyloxime<unk> 3-(O-carboxymethyl)oxime; P4-3-CMO), P1-185<unk> 3-O-(L-valine)-E-oxime), EIDD-1723<unk> 20E-O-(phosphonooxy)methyloxime sodium salt), EIDD-036<unk> 20-oxime; P4-20-O), and VOLT-02 (chemical structure unreleased), have been developed as water-soluble prodrugs of<unk> and its neurosteroid metabolites. Synthesis Chemical syntheses of<unk> have been published.
Progesterone 
Estrogen 
Estrogen
Androgen
Estradiol 
Estradiol
Methyltestosterone
Progestogen