Year

2000

Degree Name

Doctor of Philosophy

Department

Department of Chemistry

Abstract

Chapter 1 of this thesis describes the structure and reactivity of the most common member of the new family of carbon allotropes, [60]fullerene. Although originally thought to be an unreactive "superaromatic" molecule, [60]fullerene is susceptible to a diverse number of reactions. [60]Fullerene and many [60]fulleffene derivatives, such as fulleryl amino acids also exhibit a wide range of biological activities.

One of the most useful reactions known in fullerene chemistry is the Bingel cyclopropanation. This facile reaction enables access to a wide range of cyclopropanated fullerene derivatives (or methanofullerenes) in acceptable yields and under mild conditions. To date, such cyclopropanation reactions were confined to malonate-derived starting materials.

Chapter 2 reports the synthesis of a number of novel cyclopropanated [60]fullerene derivatives that were prepared from [60]fullerene and readily available N- (diphenylmethyleneglycinate) esters using Bingel reaction conditions. Although deprotection of the N-terminus or C-terminus of these protected methanofullerenes was not forthcoming, a novel reductive ring-opening of these methanofullerenes was discovered to yield a new class of α-fulleryl glycine derivatives. Although deprotection of these derivatives was also unsuccessful, this new reductive ring-opening technique provided access to a new range of fullerene derivatives.

In chapter 3, the synthetic strategy described in chapter 2 was extended to produce multifunctionalised [60]fullerenes by utilising tether-directed synthesis. The resultant tethered bis-N-(diphenylmethyleneglycinate) esters afforded [60]fulleryl bisadducts of unexpected regiochemistries when compared to cognate tethered bismalonic esters. The unexpected regiochemistry of the major products was unambiguously confirmed by 13C-13C connectivity experiments using the 2D INADEQUATE experiment.

In an effort to provide insight into the observed regiochemical differences of the tethered bis-N-(diphenylmethyleneglycinate) esters and their cognate tethered bismalonic esters, mechanistic and computational studies were conducted to investigate the mechanism of N-(diphenylmethyleneglycinate) ester addition under Bingel reaction conditions. No definitive conclusion was made as to why the observed regiochemistries between the two tethered systems differed. A mixed malonate N- (diphenylmethyleneglycinate) ester tether was synthesised in an effort to determine the fundamental factors governing the regiochemistry of addition. Unfortunately no bisadduct was observed under double Bingel reaction conditions. Under mono-Binge! reaction conditions however, a cyclopropanation occurred exclusively at the N- (diphenylmethyleneglycinate) ester site, providing evidence of this site being significantly more reactive than its malonic ester counterpart. This study was reported in chapter 4.

Chapter 5 reports the results of attempts at the double reductive ring opening reaction of the bis-N-(diphenylmethyleneglycinate) ester fulleryl adducts. Under reductive ring-opening conditions, an unexpected ring-opened monoadduct rather than the expected double ring-opened bisadduct was formed. This unexpected product is thought to arise via the elimination of one of the substituents much akin to a retro- Bingel-type reaction. This reaction was shown to be tether-independent by the formation of the corresponding elimination ring-opened monoadduct from a nontethered bismethanofullerene precursor.

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