Synthesis of 17α-substituted ethynylestradiols: Potential ligands for drug vectors

17α-substituted ethynylestradiols, derived from estrone, were converted to their corresponding 17α-(bromo- or iodo-propargyl)estrone intermediates. Nucleophilic substitution onto these moieties with malonate diester followed by hydrolysis and complexation with cis-Pt(Me 2en)I 2 (Me 2en = N, N-dimethylethylenediamine) gave cis-Pt(Me 2en)(2-(3-(17β-estradiol-17α-yl)-prop-2-ynyl)malonato) 7, thus demonstrating that these estrogen-derived compounds can be used to synthesize stable Pt(II) complexes. The 3-(17β-estradiol-17α -yl)-prop-2-ynyl-1-sulfanylethylthiol 23 was also prepared.