Synthesis and Biological Evaluation of Ferrocene-Containing Bioorganometallics Inspired by the Antibiotic Platensimycin Lead Structure

The recent discovery of the natural product platensimycin (1) as a new antibiotic lead structure has triggered the synthesis of numerous organic derivatives for structure−activity relationships (SAR) in order to improve the poor in vivo efficacy of 1. The synthesis, characterization, and biological evaluation of the first four ferrocene-containing bioorganometallic compounds based on the platensimycin lead structure are reported herein, namely 3-(4,4-diferrocenoylpentanamido)-2,4-dihydroxybenzoic acid (2), 3-(4,4-diferrocenoylbutanamido)-2,4-dihydroxybenzoic acid (3), 3-{4-(acetylferrocenoyl)butanamido}-2,4-dihydroxybenzoic acid (4), and 3-(4-ferrocenoylbutanamido)-2,4-dihydroxybenzoic acid (5). All new compounds were unambiguously characterized by all common analytical methods, including 1H and 13C NMR, mass spectrometry, IR spectroscopy, and elemental analysis. Furthermore, the single-crystal X-ray structures of methyl 4,4-diferrocenoylbutanoate (9), methyl 4,4-diferrocenoylpentanoate (10), 4,4-diferroc...