Pyrrolo fullerene

Photolytic cleavage of 2,3-disubstituted 2H-azirines or monoaryl-2H-azirines provides access to nitrile yiides with the structure 280.1,3-Dipolar cycloaddition of the in situ generated yiides to Cjq affords mono- or disubstituted pyrrolo fullerenes such as 281 (Scheme 4.50) [319, 320]. Aliphatic 2H-azirines are not reactive, as they have shorter excitation wavelengths than the phenylic substituted 2-azirines. 

Irradiation of 2,3-diphenyl-2//-azirine in the presence of fullerene leads to the formation of mono- and oligo adducts (98,99). A monoadduct, l,9-(3,4-dihydro-2,5-diphenyl-2//-pyrrolo)fullerene-60 was isolated and characterized. Mechanistic studies showed that under conditions of direct irradiation it was formed by a classic nitrile ylide cycloaddition but in the presence of 1,4-napthalenedicarbonitrile (DCA) it resulted from reaction of the radical cation intermediate 108. Cycloaddition reactions have also been carried out with diaza-phospholes and diazaarsoles (100) to give adducts of the type 189 (A = As,P) and with cyanogen to give 190 and with aryldiazocyanides where addition to both the azo moiety and the cyano group were observed (101). 

Finally, 5(4Ff)-oxazolones react as masked 1,3-dipoles with nitrileimines, l-nitroso-2-naphthol and [60]fullerene to give 1,2,4-triazoles, naphth[l,2-ci oxazoles and 5 -phenyl-2 7/-pyrrolo[3, 4 l,2][60]fullerene, respectively. 

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