Convergent, regioselective synthesis of tetrakisfulleroids from C(60)

An efficient synthesis of the two diastereomeric tetrakisfulleroids 14a and 14b is described starting from the readily accessible trans-1 bis-Diels-Alder adduct 12. The challenging issue of generating multiple bond scissions regiochemically within the fullerene framework, here as [5,6] open systems (fulleroids), is simplified into performing two separate regiocontrol phases. The initial bisadduct 12 can only undergo syn or anti photochemically promoted intramolecular tandem [4 + 4] and retro [2 + 2 + 2] rearrangements, giving the two isomers 14a and 14b in an unexpected 1:4 ratio. Interestingly, the UV-vis absorption spectra of these two isomers are quite different even though their local chromophore perturbations are distant from each other.