Patent ID: 7947667

Claim:
A method of preparing a fulvestrant composition while largely eliminating a 2-bromo impurity comprising: aromatizing 3-oxo-7-{9-[(4,4,5,5,5-pentafluoropentyl)sulfanyl]nonyl}estr-4-3n-17-yl acetate in the presence of an acylating agent under conditions such that 7-{9-[(4,4,5,5,5-pentafluoropentyl)sulfanyl]nonyl}estr-1,3,5(10)triene-3-17-diyl diacetate is formed; reacting 7-{9-[(4,4,5,5,5-pentafluoropentyl)sulfanyl]nonyl}estr-1,3,5(10)triene-3-17-diyl diacetate and a base under conditions such that 7-{9-[(4,4,5,5,5-pentafluoropentyl)sulfanyl]nonyl}estr-1,3,5(10)triene-3-17-diol is formed; reacting 7-{9-[(4,4,5,5,5-pentafluoropentyl)sulfanyl]nonyl}estr-1,3,5(10)triene-3-17-diol and an oxidizing agent under conditions such that a fulvestrant composition if formed; and purifying said fulvestrant composition by crystallization.