title: Alternative synthesis for the preparation of 16α-[(18) F]fluoroestradiol.
abstract: We have developed a new precursor, 3,17β-O-bis(methoxymethyl)-16β-O-p-nitrobenzenesulfonylestriol (14c) of 16α-[(18) F]fluoroestradiol ([(18) F]FES). Although we could not selectively protect the C17 alcohol in the presence of the C16 alcohol, we were able to prepare and chromatographically isolate the desired C16 TBDMS, C17,C3-dimethoxymethyl (diMOM) protected estriol derivative and convert into the ultimate fluorination precursor. The MOM protective group proved to be more quickly removed than the cyclic sulfate group. The di-MOM protective precursor at the C3 and C17 alcohols instead of a cyclic sulfate group shortened hydrolysis time. We prepared three different sulfonate precursors at C16 alcohol. After checking their reactivity in the [(18) F]fluorination step and considering the stability of the precursors, we obtained the best results with nosylate precursor 14c.
authors.affiliation: Research Institute of Labeling, FutureChem Co. Ltd., 388-1 Pungnap-2-dong, Songpagu, Seoul, 138-736, Korea.
authors.forename: Hee Seup
authors.initials: HS
authors.lastname: Kil
authors.forename: Han Yang
authors.initials: HY
authors.lastname: Cho
authors.forename: Sang Ju
authors.initials: SJ
authors.lastname: Lee
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Oh
authors.forename: Dae Yoon
authors.initials: DY
authors.lastname: Chi
mesh_terms: D004958:Estradiol / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D007553:Isotope Labeling / Q000379:methods*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*
chemical_list: D019275:Radiopharmaceuticals; D004958:Estradiol; C043436:16-fluoroestradiol
keywords: 16α-[18F]Fluoroestradiol; PET; [18F]FES; imaging of estrogen receptor; radiopharmaceutical