D-Ring alkylamine derivatives of estradiol: effect on er-binding affinity and antiestrogenic activity

A series of 17α-, 15α-, and 15β-(butyl methyl alkylamide)-estradiol derivatives (4–10) were synthesized from estrone and tested for the estrogen receptor binding affinity, uterotrophic activity, and antiuterotrophic activity. By moving the alkylamide side chain from B-ring (7α-position) or C-ring (11β-position) to D-ring (17α, 15α or 15β-positions) a dramatical decrease of the RBA and no antiestrogenic activity in uterine weight assay was observed. These results extend to D-ring the SAR study of this family of steroid antiestrogens. In addition, we also correct the C15-stereochemistry of compounds 5–10, which was incorrectly attributed in a previous paper.