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

Metal-organic cages have served as masks to effect the regioselective functionalization of C60. The enantioselective functionalization of C60 remains challenging, however, requiring complex chiral tethers or challenging chromatography. We report a means of defining up to six stereocentres on C60, achieving both enantioselective and regioselective fullerene functionalisation. This method involves stereochemical information transfer from a chiral formylpyridine, through the framework of an enantiopure cage incorporating it, to a series of regio- and stereochemically defined C60 adducts. The surrounding cage is then opened with retention of fullerene stereochemistry. The chiral formylpyridine thus ultimately dictates the stereochemistry of these chiral fullerene adducts without being incorporated into them. The cage acts both as the substrate and “blueprint” for the chiral information imprinted into the fullerene adducts, which form stereoselectively with a distance of up to 6 carbon atoms between stereocentres. Such chiral fullerene adducts may become useful in devices requiring circularly-polarized light manipulation.