One-Pot Enantioselective Extraction of Chiral Fullerene C76 Using a Cyclic Host Carrying an Asymmetrically Distorted, Highly π-Basic Porphyrin Module

Optical resolution of nonsubstituted chiral fullerenes such as C-76 is one of the most challenging subjects in host-guest chemistry. The novel cyclic host 1(2H), which bears a meso-diaryl-B-octaethylporphyrin (P-2H) unit on one side and its chiral N-2-acetoxyethyl derivative (PN-EtOAc) on the other, traps C-76 enantioselectively in its cavity and furnishes 7% enantiomeric excess in a single extraction. Control experiments using reference hosts indicated the importance of the high pi-basicity and large asymmetric distortion of the chiral N-substituted porphyrin unit (PN-EtOAc) in 1(2H) for the enantioselection of C-76.