Mechanochemical Deracemization: A Sustainable Approach to Enantiopurity.

We introduce mechanochemical deracemization (MCDR) as a novel strategy for obtaining enantiopure compounds. This study demonstrates the successful transposition of six archetypical deracemization reactions from a solvent-based to a solvent-minimized ball milling environment. The scope includes a ketone, isoindolinones, imines, an ester, and an inorganic compound, all of which deracemized successfully.

Investigation of the Binary System of Proxyphylline Enantiomers: Structural Resolution and Phase Diagram Determination.

The solid-state landscape of proxyphylline (PXL), a chiral derivative of theophylline crystallizing as a racemic compound, was extensively investigated by means of thermal analyses and diffraction techniques. This study revealed the presence of five distinct polymorphic forms that were characterized: two polymorphs of the racemic mixture and three polymorphs of the pure enantiomer. The nature of each solid phase was confirmed by combining the different analytical techniques, revealing the presence of a thermodynamically stable racemic compound, RI (= 134 °C), in equilibrium with the stable enantiopure crystal form, EI ( = 148.

A Greener Pathway to Enantiopurity: Mechanochemical Deracemization through Abrasive Grinding.

We report the first case of mechanochemical deracemization by using liquid-assisted abrasive grinding. The target molecule is a precursor of Paclobutrazol, an important fungicide and plant growth inhibitor. Using mechanochemical deracemization, we are even able to transform a 10 % ee scalemic mixture of this latter in an enantioenriched product of 97 % ee in a couple of hours.

Reinvestigating the Preferential Enrichment of DL-Arginine Fumarate: New Thoughts on the Mechanism of This Far from Equilibrium Crystallization Phenomenon.

Preferential enrichment (PE) is a crystallization process, starting from either a racemic of slightly enantio-enriched solution (ca. +5%) that results in a high enantiomeric excess in the liquid phase (>+90%ee) and a slight opposite excess in the deposited crystals (−2 to −5%ee). The mechanism(s) of this symmetry-breaking phenomenon is (are) still a matter of debate since it eludes rationalization by phase diagram formalism.

Deracemization in a Complex Quaternary System with a Second-Order Asymmetric Transformation by Using Phase Diagram Studies.

Invited for the cover of this issue is the group of Gérard Coquerel at Université de Rouen Normandie. The image depicts a pyramid-like tetrahedron of the quaternary phase diagram showing where symmetry breaking can take place. Read the full text of the article at 10.