Synthesis and Functionalization of Symmetrical 2,5-Diaryl Fulleropyrrolidines: Ferric Perchlorate-Mediated One-Step Reaction of [60]Fullerene with Arylmethanamines

A series of scarce N-unsubstituted 2,5-diaryl fulleropyrrolidines as cis isomers could be prepared via the facile one-step reaction of [60]fullerene with N-unsubstituted arylmethanamines promoted by cheap and easily available ferric perchlorate. Nevertheless, the reaction of N-substituted arylmethanamines with [60]fullerene under the same conditions gave different experimental results. N-Methylbenzylamine formed N-methyl 2,5-diphenyl fulleropyrrolidine as a trans isomer, and N,N-dibenzylamine unexpectedly afforded the N-unsubstituted 2,5-diphenyl fulleropyrrolidine as a cis isomer. Intriguingly, high stereoselectivity for all 2,5-diaryl fulleropyrrolidines could be observed although both cis and trans isomers were possibly formed. N-Unsubstituted fulleropyrrolidine could be further converted to N-substituted fulleropyrrolidines under the assistance of an acid chloride or an isocyanate. A possible reaction pathway leading to 2,5-diaryl fulleropyrrolidines is also proposed.