Estradiol diundecylenate (brand name Etrosteron), or estradiol diundecenoate, also known as 17ò-estradiol 3,17ò-diundec-10-enoate, is a semisynthetic steroidal estrogen and an estrogen ester â specifically, the 3,17ò-diundecylenate ester of estradiol â which was previously marketed in Argentina.