Synthesis and self-sensitized photo-oxidation of 2-fulleropyrrolines by palladium(ii)-catalyzed heteroannulation of [60]fullerene with benzoyl hydrazone esters.

A convenient and efficient Pd(OAc)2-catalyzed N-heteroannulation reaction of [60]fullerene with benzoyl hydrazone esters was exploited to synthesize novel and scarce N-unsubstituted 2-fulleropyrrolines via the formation of C-C and C-N bonds. Besides, the self-sensitized photo-oxidation of 2-fulleropyrrolines was first discovered under very mild conditions to yield a ketoamide fullerene derivative in high yields. The reaction kinetics of this self-sensitized photo-oxidation has been explored, indicating that this photo-oxidation process is a first-order reaction possessing a low reaction activation energy (2.79 kJ mol-1). Moreover, a possible mechanism related to the observed products was proposed.