Chiral Symmetry Breaking of Thiohydantoins by Attrition-Enhanced Deracemization

Abstract

Chiral symmetry breaking of thiohydantoins by attrition-enhanced deracemization was performed. It was found that three thiohydantoins afforded conglomerate crystals, and their absolute structures were determined by single crystal X-ray structure analysis. The effect of substituents on the racemization rate via a ring-opening and -closing reaction was investigated experimentally and computationally. Attrition of the crystals of racemic thiohydantoins in the presence of a catalytic amount of base promoted deracemization, leading to optically active thiohydantoins with excellent enantiomeric purity (94–96% ee) without any external chiral source.