Possibilities of Exploiting Kinetic Control in the Continuous Fractional Crystallization of Diastereomeric Mixtures

Abstract

For rapid and kinetic control-influenced resolutions, it is advisable to choose a resolving agent with the highest possible eutectic composition (eeEuResAg). It may also be advantageous to add the crystalline resolving agent directly to the solution of the racemic compound. In addition, the use of a quasi-racemic resolving agent or amphoteric resolving agent can provide kinetic resolution. In some cases, the continuous fractional crystallization of diastereomeric salts requires the salt of the resolving agent (Ca2+, Na+, etc.) or other achiral additives (thiourea) that cause rapid crystallization and provide high diastereomeric purity. A further advantage may be the sequential use of the same resolving agent that is capable of forming crystalline diastereomers with both enantiomers when using kinetic control (tandem resolution).

Dual space divergence in small molecule quasiracemates: benzoyl leucine and phenylalanine assemblies

“…1,2 Because these materials exploit the molecular shape and chirality of the quasienantiomeric components in supramolecular assembly, it is not surprising that this approach has successfully been applied to construct material architectures that require precise control over the alignment of the building blocks. 3–16 Similar to the concepts of polymorphism 17 and crystal structure prediction, 18–20 the phenomenon of quasiracemate formation is straightforward and direct in principle. However, a considerable challenge exists in defining the structural boundaries and shape space of the assembled materials.…”