Nickel-promoted first ene-diyne cycloaddition reaction on C60: synthesis and photochemistry of the fullerene derivatives

A new and convenient one-step synthetic approach to cyclohexadiene derivatives of C60 by means of a nickel-mediated cycloaddition of bisalkynes to C60 is presented. This method for constructing a fused cyclohexadiene ring on C60 based on a nickel-promoted (2+2+2) cycloaddition of 1,6-diynes is general for various bisalkynes. Results indicate that the cycloaddition of diynes to C60 takes place across a 6,6-ring junction on the fullerene. They also demonstrate that nickel phosphine complexes can effectively promote cycloaddition of 1,6-diynes to C60.