Product Name: Diethylstilbestrol
Synonyms: neo-oestranol1;neo-oestranoli;New-Estranol 1;NSC-3070;OeKolp;Oestrol vetag;oestrolvetag;Oestromenin
CAS: 56-53-1
MF: C18H20O2
MW: 268.35
EINECS: 200-278-5
Melting point: 170-172 °C(lit.)
Boiling point: 351.51°C
Density: 1.1096
Storage temp.: 0-6°C
Appearance: white crystalline powder

At first glance, it might be surprising that synthetic nonsteroidal molecules such as diethylstilbestrol (DES) could have the same activity as estradiol or other estrogens. DES can be viewed, however, as a form of estradiol with rings B and C open and a six-carbon ring D. The activity of DES analogs was explained in 1946. It was proposed that the distance between the two DES OH groups was the same as the 3-OH to 17-OH distance of estradiol; therefore, they could both fit the same receptor. Medicinal chemists have shown the OH-to-OH distance to be actually 12.1 ? in DES and 10.9 ? in estradiol. In aqueous solution, however, estradiol has two water molecules that are hydrogen bonded to the 17-OH. If one of the two water molecules is included in the distance measurement, there is a perfect fit with the two OH groups of DES. This suggests that water may have an important role for estradiol in its receptor site.

It is now generally accepted that the estrogens must have a phenolic moiety for binding, but some investigators propose that the receptor may be flexible enough to accommodate varying distances between the two key hydroxyls. This point about estrogens needing a phenolic ring for high-affinity binding to the ER is critical. Steroids with a phenolic A ring and related phenolic compounds lack high-affinity binding to the other steroid hormone receptors.