Ferricenium hexafluorophosphate

The iron-mediated synthesis of 2-oxygenated carbazole alkaloids is limited and provides only a moderate yield (11%) for the oxidative cyclization to 2-methoxy-3-methylcarbazole using iodine in pyridine as the reagent [90]. Ferricenium hexafluorophosphate is the superior reagent for the iron-mediated arylamine cyclization leading to 3-oxygenated carbazoles (Scheme 12). Electrophilic substitution of the arylamines 16 with the complex salt 6a leads to the iron complexes 17. Oxidative cyclization of the complexes 17 with an excess of ferricenium hexafluorophosphate in the presence of sodium carbonate affords... 

Alternatively, using the iron-mediated arylamine cyclization, a short access to carazostatin (247), albeit in lower yield, was achieved. The oxidation of the complex 714 with ferricenium hexafluorophosphate in the presence of sodium carbonate... 

An alternative method for the oxidative cyclization of the arylamine-substituted tricarbonyl(r -cyclohexa-l,3-diene)iron complex (725) is the iron-mediated arylamine cyclization. Using ferricenium hexafluorophosphate in the presence of sodium carbonate provided hyellazole (245) directly, along with the complex 727, which was also converted to the natural product (599,600) (Scheme 5.71). 

Oxidative cyclization of alkylamines tethered to tricarbonyl-cyclohexadiene complexes facilitates an easy route to synthesis of indole derivatives. The ring closure is brought about using a single-electron-transfer (SET) agent, such as ferricenium hexafluorophosphate. Yeh et al. reported the first intramolecular radical cyclization of jf-diene)Fe(GO)3 complexes, to afford racemic cyclic tertiary alcohols. 

Oxidative cyclisation of tricaibonyliron-cyclohexadiene complexes with an alkylamine side-chain to iron-complexed substituted indole derivatives was reported to be easily accon lished in high yield using single-electron transfer (SET) oxidising agents such as ferricenium hexafluorophosphate. The method was employed as a synthetic approach to the framework of mitomycin antibiotics. 

Here, then, the ferrocenyl compounds act as hydroxyl radical scavengers. On the other hand, as depicted in the simplified Scheme 7, ferricenium salt, exemplified by ferricenium hexafluorophosphate, undergoes reduction to ferrocene in the presence of glutathione (GSH) with simultaneous formation of the very same hydroxyl radical that was scavenged in the preceding reaction sequence. A more recent study... 

Besides EXAFS and related techniques, electrochemical methods have been used extensively to characterize metals in ILs. Lagunas et al. studied the electrochemistry of the ferricenium/ferrocene couple in Bmim-based ILs [194, 195], In a similar study, Rogers et al. studied ferrocene and cobaltocenium hexafluorophos-phate in a range of common ILs, including phosphonium ILs. The authors report solubilities and diffusion coefficients for a variety of concentrations and suggest that both ferrocene and cobaltocenium hexafluorophosphate are useful and reliable internal standards for use in ILs [196],... 

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