Equilenin, also known as 6,8-didehydroestrone, as well as estra-1,3,5(10),6,8-pentaen-3-ol-17-one, is a
naturally occurring steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...
al
estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal a ...
obtained from the
urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellular ...
of
pregnant
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ...
mares
A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than fou ...
.
It is used as one of the components in
conjugated estrogens
Conjugated estrogens (CEs), or conjugated equine estrogens (CEEs), sold under the brand name Premarin among others, is an estrogen medication which is used in menopausal hormone therapy and for various other indications. It is a mixture of th ...
(brand name Premarin).
It was the first complex natural product to be fully synthesized, in work reported by 1940 by
Bachmann and
Wilds.
Chemistry
Synthesis
Total synthesis
The synthesis developed by the
Bachmann group started from Butenand's ketone
– the 7-methoxy
structural analog
A structural analog (analogue in modern traditional English; Commonwealth English), also known as a chemical analog or simply an analog, is a compound having a structure similar to that of another compound, but differing from it in respect to a ...
of
1,2,3,4-tetrahydrophenanthren-1-one – and which can be readily prepared from 1,6-
Cleve's acid.
The approach was based on well-established transformations like the
Claisen condensation, the
Reformatsky reaction, the
Arndt–Eistert reaction, and the
Dieckmann condensation.
described this preparation as ending the era preceding the post-World War II work of
Robert Burns Woodward that introduced
enantioselective synthesis
Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecul ...
;
in this synthesis, a mixture of stereoisomers were prepared and then
resolved,
and the choice of target was partly because of the existence of only two chiral carbons and hence only four stereoisomers.
The overall yield of the synthesis was 2.7% based on a twenty-step process starting from Cleve's acid.
See also
*
List of estrogens § Equine estrogens
References
{{Estrogen receptor modulators
Sterols
Phenols
Estranes
Estrogens
Ketones