Continuous Flow Synthesis of Fullerene Derivatives

Various fullerene-based electron acceptor materials for organic photovoltaic applications were prepared via [3 + 2] and [4 + 2] cycloadditions using a continuous flow approach. The 1,3-dipolar cycloaddition of the tosylhydrazone precursor and the Diels-Alder cycloaddition of indene to either C-60 or C-70 under conventional batch reaction conditions were translated to the continuous flow process. By varying the residence time, temperature, and equivalents of cycloaddition reagent, significant improvements in yields and reaction times were achieved over conventional batch processes.