Ethyl 4-Ene-4-ferrocenyl-5,5-bis-(4-hydroxyphenyl)-pentanoate

The ferrociphenol family is a group of molecules in which a ferrocenyl moiety is connected to at least one 4-hydroxyphenyl group through a C-C double bond. Among them, ferrocidiphenols in which the double bond is substituted by two gem 4-hydroxyphenyl groups have been largely studied, demonstrating interesting anticancer properties. The fourth available position of the double bond could be substituted by a simple ethyl group (1a) inherited from Tamoxifen, but also by ethyl or methyl acetate, propionate, butanoate, pentanoate (1b-g), hydroxyethyl or hydroxypropyl (1h–i). Ethyl 4-ene-4-ferrocenyl-5,5-bis-(4-hydroxyphenyl)-pentanoate 1e shows an IC50 on the MDA-MB-231 breast cancer cell line very close to that of 1a. These compounds were synthesized in moderate to good yields by McMurry coupling reaction from the corresponding ketones. Ethyl 4-ene-4-ferrocenyl-5,5-bis-(4-hydroxyphenyl)-pentanoate (1e) was fully characterized by 1H NMR (including COSY), 13C NMR (including DEPT135), low resolution mass spectrometry, HRMS, infrared spectroscopy, elemental analysis, and X-ray diffraction (XRD). The data of already published crystal structures of five structurally related ferrocidiphenols are also included for comparison purposes.