A Potentially Limitless Chiral Pool via Conglomerate Crystallisation: Unidentified Spontaneous Resolution in the CSD.

Conglomerate crystallisation is the behaviour responsible for spontaneous resolution and the discovery of molecular chirality by Pasteur. The phenomenon of conglomerate crystallisation of chiral organic molecules has been left largely undocumented and offers synthetic chemists a potential new chiral pool not reliant on biological systems to supply stereochemical information. While other crystallographic behaviours can be interrogated by automated searching, conglomerate crystallisations are not identified within the Cambridge Structural Database (CSD) and are therefore not accessible by conventional means. By conducting a manual search of the CSD, a list of over 1,700 chiral species capable of conglomerate crystallisation was curated by inspection of the synthetic routes described in each publication. The majority of these are produced by synthetic chemists who seldom note and rarely exploit the implications this phenomenon can have on the enantioenrichment of their crystalline materials. We propose that this list represents a limitless chiral pool which will continually grow in size as more conglomerate crystals are synthesised and recorded.