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

The regioselective functionalization of C-60 remains challenging, while the enantioselective functionalization of C-60 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 C-60. 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 C-60, 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 C-60 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.

Automated summary

The selective chemical modification of C-60 remains a challenge, and achieving enantioselective functionalization is even more difficult due to the lack of suitable chiral reagents or separation methods. In this study, we demonstrate a strategy for introducing up to six stereocenters on C-60 with high enantioselectivity. By using a metal-organic cage built from a chiral formylpyridine, we can selectively react fullerenes inside the cage with the cage edges through chemo-, regio-, and stereo-selective Diels-Alder reactions, controlling the stereochemistry of the resulting chiral fullerene adducts. These chiral fullerene adducts hold promise for applications in devices requiring circularly polarized light manipulation.