Kinetics and regioselectivity in the Diels-Alder reaction of fulleroids vs. Methanofullerene and C_(60)

摘要

Fulleroids, obtained from the 1,3-dipolar cycloaddition of fullerene with a diazoalkane, have a [5,6]-open methylene bridge and two highly twisted bridgehead double bonds. The [H,H]- and [H,CN]-substituted fulleroids were found to display significantly enhanced and regioselective Diels-Alder addition as compared with the [6,6] closed methanofullerene and C_(60) with 2,3-dimethyl-1,3-butadiene, but reduced and nonregioselective addition with cyclopentadiene. NMR analysis of the 1:1 adduct and quantum calculations indicated that the high reactivity and the regioselective addition are due to π-orbital misalignment at the bridgehead double bond.