Oxygenation fullerene adducts

F. Regioselective Self-sensitized Oxygenation of Fullerene Adducts. 857... 

TABLE 15. Regioselectivity in the self-sensitized oxygenation of fullerene adducts"... 

Among the reactions applied in the synthesis of fullerene derivatives cycloaddition reactions such as [2 + 1]-, [2 + 2]-, [3 + 2] and [4 + 2] cycloadditions play a dominant role. In these reactions ring-fused fullerene derivatives are obtained, at least with incorporation of heteroatoms such as oxygen, nitrogen, or silicon. In this section photochemical reactions leading to cycloalkyl ring-fused fullerene adducts will be presented. Photocycloaddition reactions leading to C6o-fused heterocycles will be discussed later. 

Averdung et al. also obtained several aziridinofullerenes by the reaction of C60 with acylnitrenes, generated by photolysis of aroylazides 85a-d, leading to the fullerene adducts 86a-d (Scheme 34) [260], In a typical experiment a solution of C6o and a five-fold excess of azide 85a-d in oxygen free 1,1,2,2-tetra-chloroethane was irradiated for 60 min in Pyrex tubes using a RPR 100 Rayonet... 

Wolff DJ, Mialkowski K, Richardson CF, Wilson SR (2001) C -fullerene monomalonate adducts selectively inactivate neuronal nitric oxide synthase by uncoupling the formation of reactive oxygen intermediates from nitric oxide production. Biochemistry 40 37 15. 

The cytotoxic and photocytotoxic effects of two water-soluble fullerene derivatives, a dendritic CL mono-adduct and the malonic acid CL tris-adduct were tested on Jurkat cells when irradiated with UVA or UVB light (Rancan et al., 2002). The cell death was mainly caused by membrane damage and it was UV dose-dependent. Tris-malonic acid fullerene was found to be more phototoxic than the dendritic derivative. This result is in contrast to the singlet oxygen quantum yields determined for the two compounds. 

The synthesis of fullerene epoxides via [2 -I- l]-photoq cloaddition of singlet oxygen has already been discussed (in the section [2 -1- l]-Photocycloaddition ). Alternatively, fullerene oxides can also be obtained by thermolysis or photolysis of the [6,6]-closed ozone adduct of Qq and C70, namely 60 3 75 and C70O3 77.Thermolysis of QqOj yields the fullerene epoxide with a [6,6]-closed structure. In contrast, photolysis resulted in the formation of the [5,6]-open oxidoannulene 76 with an ether structure (Scheme 32). 

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