Cocrystallization-Induced Spontaneous Deracemization: A General Thermodynamic Approach to Deracemization.

Processes leading to enantiomerically pure compounds are of utmost importance, in particular for the pharmaceutical industry. Starting from a racemic mixture, crystallization-induced diastereomeric transformation allows in theory for 100 % transformation of the desired enantiomer. However, this method has the inherent limiting requirement for the organic compound to form a salt. Herein, this limitation is lifted by introducing cocrystallization in the context of thermodynamic deracemization, with the process applied to a model chiral fungicide. We report a new general single thermodynamic deracemization process based on cocrystallization for the deracemization of (R,S)-4,4-dimethyl-1-(4-fluorophenyl)-2-(1H-1,2,4-triazol-1-yl)pentan-3-one. This study demonstrates the feasibility of this novel approach and paves the way to further development of such processes.