Recent encounters with atropisomerism in drug discovery.

Atropisomerism is stereochemistry arising from restricted bond rotation that creates a chiral axis. Atropisomers are subject to time-dependent inversion of chirality via bond rotation, a property which in drug molecules introduces complexity and challenges for drug discovery and development processes. Greater recognition of the occurrence of atropisomerism and improved characterization techniques have helped medicinal chemists successfully advance atropisomeric drug molecules. This review provides recent examples of atropisomerism encountered in medicinal chemistry efforts and the strategies used to address the accompanying challenges.