Anthracene electroreduction

Liu HY, Abdalmuhdi I, Chang CK, Anson FC. 1985. Catalysis of the electroreduction of dioxygen and hydrogen peroxide by an anthracene-linked dimeric cobalt porphyrin. J Phys Chem 89 665. 

The treatment of the bromoacetal (255) with catalytic amounts ( 10%) of a Co(I) species, generated by the electroreduction of cobaloxime (232) in an Me0H-LiCl04 system at —1.8 V, produces the cis-fused adduct (256) in 60 70% yield (Scheme 96) [392]. Cathodic reduction is used for the synthesis of a [Co(CO)3PBu3] complex in a methanol-methyl formate medium, which catalyzes the alkoxycarbonylation of dichloromethane to dimethyl mal-onate in up to 75% yield [393]. The Co(II) complexes are found to be effective for the homogeneous reduction of gem-dichlorocyclopropanes in the presence of anthracene [394]. The formation of the C—C double bond of (258) may be ascribed to the a-elimination of the Co-H species. Thus, benzalchloride (257) can be converted to a mixture consisting primarily of ds- and trans-stilbenes (258) by the action of electrogenerated Co(I)(salen) (Scheme 97) [395-398]. 

In several examples the reductive halide-hydrogen exchange has been studied on a preparative scale. For example, the indirect electroreduction of 2-chloropyridine in DMF using anthracene as mediator gives pyridine in 83-86 % yield 2 . For the dehalogenation of 1-chlorohexane (80% yield), naphthalene is applied as redox catalyst. Similarly, 6-chloro-hexene yields 1-hexene (60%) and methylcyclopentane (25%), which is the product of the radical cyclization . The indirect electrochemical reduction of p- and y-bromocarboxylic esters forms coupling and elimination products besides the dehalogenated products... 

Fawcett and Jaworski [118] have studied the electroreduction of -dicyanoben-zene and anthracene in five nonaqueous solvents using 0.1 M tetrabutylammonium perchlorate as background electrolyte. The authors tried to explain the rate constants corrected for the double-layer influence in terms of the Marcus theory, since in 1983 the importance of solvent dynamics on the rate of charge transfer was not clearly understood. No correlation was found between log and the y parameter, pointing to a more complex behavior of these systems. 

Nanometer-sized monolayer-protected gold clusters functionalized with anthraquinone by using l-(l,3-dithiapropyl)anthracene-9,10-dione were used to mediate electroreduction of 1,1-dinitrocyclohexane [54a]. The enhancement in catalytic efficiency for cluster-bound anthraquinone compared to its monomer was ascribed to the smaller diffusion coefficient of the cluster-bound... 

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