Multi-Ferrocenyl Aryl Ethers – Applying Nucleophilic Aromatic Substitution Reactions to Aryl Fluorides

Abstract

The reaction of ferrocenol [FcOH; Fc = Fe(η5-C5H5)(η5-C5H4)] with aryl fluorides ArH6–nFn(n = 3–6) within a nucleophilic aromatic substitution reaction (SNAr) gave ferrocenyloxy-substituted fluorobenzenes of general type C6H0–3F1–5(OFc)1–5. For 1,3,5-C6H3F3, 1,2,4,5-C6H2F4, and C6H6–nFn(n = 5,6), one, two, and three F atoms, respectively, could be replaced by FcO units. The reaction of 1,4-(OFc)2-C6F4with additional amounts of FcOH afforded the tetra- and penta-substituted arenes 3,6-F2-C6(OFc)4and C6F(OFc)5. Electrochemical investigations of both compounds showed four or five Fc/Fc+related reversible redox processes that were attributed to electrostatic interactions. The addition of C6F6as the electrophile after the anionic phospho-Fries rearrangement of a ferrocenyl phosphate (1,3-O→C migration) to the 1,2-substituted ortho-phosphonato ferrocenol, resulted in the formation of the respective ortho-functionalized ether. The constitution of all compounds was verified by using19F NMR spectroscopy. Steric hindrance of the ortho-substituent resulted in a doubling of the signal sets for the C6F5moiety in the13C{1H} and19F NMR spectra. The identity and substitution pattern of five compounds could also be determined by using single-crystal X-ray diffraction analysis, revealing the 1,4-constitution of double functionalized derivatives, intermolecular non-classical C–H···F interactions and π interactions.