Reversible Stereodivergent Cycloaddition of Racemic Helicenes to [60]Fullerene: A Chiral Resolution Strategy.

[60]Fullerene and its rarely explored reversible covalent chemistry have been harnessed as an efficient alternative for the chiral resolution of racemates. By using only catalytic amounts of chiral agents, stereodivergent 1,3-dipolar cycloadditions of racemic helicenes onto [60]fullerene were carried out. The formed helicene/fullerene diastereomers were easily separated by conventional chromatography, and afterward, a simple catalyzed 1,3-dipolar retro-cycloaddition afforded helicene starting materials in high optical purity.