Estramustine

Estramustine (INN, USAN, BAN) is an estrogen and cytostatic antineoplastic agent which was never marketed. It is a carbamate derivative of estradiol and acts in part as a prodrug of estradiol in the body. Estramustine phosphate, the C17β phosphate ester of estramustine and a prodrug of estramustine, estromustine, estradiol, and estrone, is marketed and used in the treatment of prostate cancer.

Synthesis
Estramustine is a carbamate derivative of the natural hormone, estradiol. The amine (ClCH2CH2)2NH is treated with phosgene to give the acid chloride of normustine. This reacts with the phenolic hydroxyl group of estradiol in the presence of a base to give estramustine.