ABSTRACT

The simplest compound of fulleropyrrolidine type, N-methylfulleropyrrolidine, is shown in Figure 19.1. The classic synthetic procedure, leading to this fullerene derivative and its numerous analogues, is the 1,3-dipolar cycloaddition of azomethine ylides32 (reactive intermediates generated in situ by many different ways, in particular by decarboxylation of ammonium salts, formed as a result of condensation of α-amino acids with aldehydes) to C60 (Prato reaction). As a result of this powerful methodology for obtaining functionalized fullerene derivatives, the fulleropyrrolidines are formed, in which a pyrrolidine ring is fused to a junction between two six-member rings of a fullerene sphere5 (Figure 19.1). When the reaction is carried out in the presence of large excesses of reagents, up to nine pyrrolidine rings can be introduced.15 The key features and strategies of this type of reaction are summarized in Refs. [5,15,17,33]; in particular, its main advantages are as follows: (1) the reactions lead individual [6,6]-closed isomers, (2) majority of precursors are commercially available or could be easily prepared, and (3) two substituents can be simultaneously introduced into the pyrrolidine cycle. Therefore, functionalization of the fullerene sphere on the Prato’s reaction basis occupies a leading place in the synthesis of fullerene derivatives to get new materials and potentially biologically active compounds.