Regioselective Unsymmetrical Tetraallylation of C60 through Palladium Catalysis

A Pd-catalyzed tetraallylation of C(60) that selectively occurs with an unsymmetrical addition pattern has been established. Treatment of C(60) with CH(2)=CHCH(2)Cl, CH(2)=CHCH(2)SnBu(3), and PdCl(2)[P(OPh)(3)](2) in 1,2-Cl(2)C(6)H(4) at 50 degrees C afforded the tetraallylated fullerene in 74% yield with virtually complete regioselectivity. Mechanistic investigations showed that (i) tetraallylation proceeds through consecutive nucleophilic/electrophilic allylations [likely via a bis(pi-allyl)palladium intermediate] and (ii) both steric (for the first diallylation) and electronic (for the second diallylation) factors are responsible for the high regioselectivity.