Estradiol benzoate cyclooctenyl ether

Estradiol benzoate cyclooctenyl ether (EBCO), or estradiol 3-benzoate 17β-cyclooctenyl ether, is a synthetic estrogen as well as estrogen ester and ether – specifically, the C3 benzoate ester and C17β cyclooctenyl ether of estradiol – which was described in the early 1970s and was never marketed.^[1][2][3][4] It has been found to have a dramatically prolonged duration of action with oral administration in animals, similarly to the related compound quinestrol (the 3-cyclopentyl ether of ethinylestradiol).^[1][5][6] A single oral dose of EBCO sustained high uterus weights for 3 weeks in rats.^[1] This long-lasting activity may be due to storage of EBCO in fat.^[1] It appears that EBCO is absorbed satisfactorily from the gastrointestinal tract, at least partially survives first-pass metabolism in the liver and intestines, and is then sequestered into fat, from which it is slowly released and activated into estradiol.^[1] In contrast to quinestrol, the oral activity of EBCO is greatly improved when it is delivered in an oil solution as opposed to an aqueous vehicle.^[1]

EBCO

Clinical data
Other names	EBCO; Estradiol 3-benzoate 17β-cyclooctenyl ether
Routes of administration	By mouth[1]
Drug class	Estrogen; Estrogen ester; Estrogen ether
Identifiers
IUPAC name [(8R,9S,13S,14S,17S)-17-[(1E)-cycloocten-1-yl]oxy-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopenta[a]phenanthren-3-yl] benzoate
CAS Number	28200-94-4
PubChem CID	6436089
ChemSpider	4940765
Chemical and physical data
Formula	C33H40O3
Molar mass	484.680 g·mol−1
3D model (JSmol)	Interactive image
SMILES C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@@H]2O/C/4=C/CCCCCC4)CCC5=C3C=CC(=C5)OC(=O)C6=CC=CC=C6
InChI InChI=1S/C33H40O3/c1-33-21-20-28-27-17-15-26(36-32(34)23-10-6-5-7-11-23)22-24(27)14-16-29(28)30(33)18-19-31(33)35-25-12-8-3-2-4-9-13-25/h5-7,10-12,15,17,22,28-31H,2-4,8-9,13-14,16,18-21H2,1H3/b25-12+/t28-,29-,30+,31+,33+/m1/s1 Key:DOFNLZKUGHVIMH-UQWKGHMASA-N

See also

• List of estrogen esters § Ethers of steroidal estrogens