Putting the Squeeze on Fullerene

Significance

Sygula and co-workers report the synthesis of an elegant bowl-shaped receptor using isocorannulenofuran as a building block and characterize the 1:1 complex formed with fullerene. Isocorannulenofuran was previously synthesized from bromocorannulene (Sygula and co-workers Org. Lett. 2006, 8, 5909-5911). Diels-Alder cyclo­addition with dibenzocyclooctadiyne gives two isomeric products and subsequent deoxygenation using low-valent titanium provides the receptor in 60% yield. The X-ray crystal structure indicates that the corannulene carbon atoms are within van der Waals contact distance from the fullerene with the shortest distance of 3.128 Å. NMR titrations in toluene provided a binding constant of 8600 M^-1.