Investigation On Transition Metal-Promoted Free-Radical Reactions Of [60]Fullerene

The functionalization of [60]fullerene (C₆₀) with various organic functional groups is an important subject in fullerene chemistry for further material and medicinal applications. Among a large number of fullerene's reactions, radical reactions of fullerenes were among the first to be investigated and continue to be of interest for fullerene functionalization. The main work presented in this dissertation is focused on the Mn(III),Cu(II) or Fe(III)-mediated free-radical addition reactions of C₆₀ with various organic compounds.1. C6o-fused lactones can be synthesized by the Mn(OAc)₃·2H₂O-mediated reaction of C₆₀with carboxylic acids, or carboxylic anhydrides, or malonic acids, or meldrum's acid. Further functionalizations of C6o-fused lactones with CH₃MgBr in THF led to the novel reductive opening of the lactone rings. However, the reaction of C₆₀-fused lactones with CH₃MgBr and DIBAL-H in toluene at ambient temperature afforded the scarce fullerene hemiketals and fullerene hemiacetals. Dehydrations of the obtained hemiketals and hemiacetals by TsOH or PPA resulted in the generation of C6o-fused dihydrofurans including the unsubstituted and simplest C₆₀-fused dihydrofuran. Reactions of unsubstituted lactone with benzylamine and allyamine afforded lactone-opened fullerols.2. The Mn(OAc)₃·2H₂O-mediated reaction of C₆₀ with acetic acid, propionic acid orphenylacetic acid could be extended to various carboxylic acids, and afforded a variety of C₆₀-fused lactones with desired structures. It should be noted that DMAP played a crucial role for the successful synthesis of lactones from carboxylic acids, byproducts were formed without the addition of DMAP.3. The Mn(OAc)₃·2H₂O-mediated reaction of C₆₀ with various carboxylic acids in theabsence of base afforded C₆₀-fused lactones and 1,4-addition products. The 1,4-addition products were difficult to prepare by common methods.4. Cu(OAc)₂·H₂O has been successfully utilized in the free-radical reaction in fullerene chemistry. Only dihydrofuran-fused C₆₀ derivatives were obtained for highly enolizable ketones such asβ-diketones andβ-keto esters with both Cu(OAc)₂·H₂O and Mn(OAc)₃·2H₂O as the oxidants. In contrast, either dihydrofuran-fused C₆₀ derivatives or methanofullerenes could be obtained as the main products selectively by choosing Cu(OAc)₂·H₂OandMn(OAc)₃·2H₂O as the oxidant when aromatic methyl ketones were used as the substrates, possibly duo to the low enolization of aromatic methyl ketones. The Cu(OAc)₂·H₂O and Mn(OAc)₃·2H₂O-mediated free-radical reaction of C₆₀ with active methylene compounds in refluxing chlorobenzene in the presence of DMAP afforded methanofullerenes instead of 1,4-addition products.5. Fe(ClO₄)₃·6H₂O has been successfully utilized in the free-radical reaction in fullerene chemistry. The Fe(ClO₄)₃-6H₂O-promoted free-radical reaction of C₆₀ with diethyl malonate or substituted diethyl malonate resulted in the formation of disubstituted C₆₀-fused lactones in the methylene position, which would be difficult to be obtained by known fullerene chemistry. The reaction of C₆₀ with ethyl 2-methylacetoacetate and ethyl acetoacetate by selecting Fe(ClO₄)₃·6H₂O as the oxidant led to the formation of fullerene hemiacetal and fullerene dihydrofuran, respectively.6. The Fe(ClO₄)₃·6H₂O-based free-radical reaction of C₆₀ with various aldehydes attained 1,3-dioxane derivatives of [60] fullerene, which was a simple, one-pot method for preparing 1,3-dioxane derivatives and gave excellent isolated yields.