Enantioselective fullerene functionalization through stereochemical information transfer from a self-assembled cage.

Abstract

The regioselective functionalization of C60 remains challenging, while the enantioselective functionalization of C60 is difficult to explore due to the need for complex chiral tethers or arduous chromatography. Metal-organic cages have served as masks to effect the regioselective functionalization of C60. However, it is difficult to control the stereochemistry of the resulting fullerene adducts through this method. Here we report a means of defining up to six stereocentres on C60, achieving enantioselective fullerene functionalization. This method involves the use of a metal-organic cage built from a chiral formylpyridine. Fullerenes hosted within the cavity of the cage can be converted into a series of C60 adducts through chemo-, regio- and stereo-selective Diels-Alder reactions with the edges of the cage. The chiral formylpyridine ultimately dictates the stereochemistry of these chiral fullerene adducts without being incorporated into them. Such chiral fullerene adducts may become useful in devices requiring circularly polarized light manipulation.