The Bingel addition of a trimalonate derived from a chiral, cyclotriveratrylene (CTV)-based tripodal tether to C60 was reinvestigated. The present use of enantiomerically pure (P)- and (M)-configured CTV units in the tether allowed the isolation of a total of four enantiomerically pure C3-symmetric tris-adducts of [60]fullerene (two from each CTV enantiomer). With the support of NMR and UV/Vis spectroscopy, electronic (ECD) and vibrational (VCD) circular dichroism spectroscopic analysis (comparison to ECD data of known compounds and to ECD and VCD data calculated by TD-DFT or ZINDO methods as part of this work) allowed a definitive determination of the following structural features for all four CTV-C60 conjugates: (i) The constitution of the fullerene addition pattern, (ii) its absolute configuration, and (iii) the absolute configuration of the CTV moiety. It is concluded that the triple Bingel addition proceeded with complete regioselectivity and negligible diastereoselectivity, affording only the trans-3,trans-3,trans-3 fullerene addition pattern in both enantiomeric forms, whereas the previously reported e,e,e motif was not formed.
