Enol radical cations in solution. Part 12. Synthesis and electrochemical investigations of a stable enol linked to a ferrocene redox centre †

Mechanistic Studies of Ce(IV)-Mediated Oxidation of β-Dicarbonyls: Solvent-Dependent Behavior of Radical Cation Intermediates

“…These experiments show that a primary isotope effect ( k H / k D ) of approximately 2 was observed in CH 3 CN and CH 2 Cl 2 whereas a k H / k D of 1.5 was found in CH 3 OH. A similar primary kinetic isotope effect ( k H / k D = 2.7 ± 0.5) has been reported by Schmittel for the deprotonation of the anisyldimesitylethenol radical cation 15a. The lower value in methanol is likely due to exchange between CH 3 OH and deuterium in the substrate.…”

“…Previous studies have shown that the oxidation of enols and their structurally related silyl enol ethers generate radical cations 10 which undergo deprotonation by solvent assistance to generate the corresponding radicals . Although these studies provide an important mechanistic framework for understanding the interrelationship between the solvent milieu, the stability of the radical cation, and follow-up reactions with solvent or substrate, many of these studies utilized sterically hindered starting materials whose structures are not representative of substrates used in organic synthesis.…”

Enol Radical Cations in Solution. 13. First Example of a Radical Dication Rearrangement. One-Electron Oxidation of Dihydrobenzofuranyl Cations Leads to Drastic Rate Enhancement in the Oxidative Benzofuran Formation from Enols

“…In the context of our ongoing investigations on the chemistry of enol radical cations in solution , we have discovered the rare event of a selective activation of a cationic intermediate via the corresponding radical dication, which shall be described here in detail . Since radical dications are usually formed through one-electron oxidation of electron-deficient cationic precursors, this class of mostly highly reactive intermediates is difficult to access.…”

Unusual ladder-like supramolecular arrangement by cooperative effect of bifurcated O–H⋯O hydrogen bonding in crystals of racemic 4-ferrocenylbutan-1,2-diol

“…In the context of our ongoing investigations on ferrocene derivatives as radical cation probes in solution 14 and enzymatic processes, 15 and as redox active surfactants we needed to prepare ferrocenebutanediol 15. Although a synthesis for 15 was already known, 16 we decided to replace the literatureknown, but lengthy synthesis by a two step route.…”