Photochemical synthesis, conformational analysis, and transformation of [60]fullerene-o-quinodimethane adducts bearing a hydroxy group

The photochemical reactions of 60]fullerene with various aromatic aldehydes or ketones 1a-n carrying an alkyl group at the ortho position were examined. Some of them afforded stable o-quinodimethane adducts 2 with a hydroxy group attached to the cyclohexene ring. The adducts 2 were found to adopt one or both of two conformers A and E, which possess pseudoaxial and pseudoequatorial hydroxy groups, respectively. The conformer ratios depended remarkably on the substituents attached to the aromatic nucleus and the cyclohexene ring. The dynamic behavior of 2 was also investigated by the VT-NMR technique.