Regioselective penta-addition of 1-alkenyl copper reagent to [60]fullerene. Synthesis of penta-alkenyl FCp ligand

We have found the conditions to achieve penta-addition of an alkenyl group to [60]fullerene in good yield with the aid of an RCu-type reagent prepared from the corresponding alkenyllithium reagent. The addition took place regioselectively at the five double bonds surrounding a pentagon in the fullerene and with retention of the stereochemistry of the alkenylcopper reagent. The reaction thus produced a cyclopentadiene embedded in the fullerene core that bears five 1-alkenyl groups (1c–e).