Chiralpedia

Dynamic Kinetic Resolution (DKR)

Paired Concept: Kinetic Resolution

Definition: Resolution combined with in situ racemization to yield >50% of the desired enantiomer.
Context: Boosts efficiency in API synthesis.
Example: Lipase DKR of secondary alcohols.
Related Terms: Kinetic Resolution, DYKAT.
Reference: Pellissier, Tetrahedron (2003).

Kinetic Resolution (KR)

Paired Concept: Dynamic Kinetic Resolution

Definition: A process in which the two enantiomers of a racemic mixture react at different rates with a chiral reagent, catalyst, enzyme, or biological system, leading to preferential conversion of one enantiomer while the other remains relatively unreacted.
Context: Kinetic resolution is one of the most widely used methods for obtaining enantiomerically enriched or enantiopure compounds. The separation arises from differences in reaction rates rather than differences in physical properties. Enzymatic resolutions (e.g., lipase-catalyzed esterifications), asymmetric catalytic transformations, and biotransformations are common examples. A classical kinetic resolution has a theoretical maximum yield of 50% for the desired enantiomer because only one enantiomer is selectively transformed while the other is recovered.
Example: The lipase-catalyzed esterification of racemic secondary alcohols often converts one enantiomer faster than the other, yielding an enantiomerically enriched ester and an enantiomerically enriched unreacted alcohol. Industrially, enzymatic kinetic resolution has been used in the preparation of chiral pharmaceutical intermediates.
Related Terms: Dynamic Kinetic Resolution (DKR), Chiral Resolution, Enantiomeric Excess (ee), Enantioselectivity, Racemate, Asymmetric Catalysis, Biocatalysis.
Reference: Kagan, H. B., & Fiaud, J. C. (1988). "Kinetic Resolution." Topics in Stereochemistry, 18, 249-330; Faber, K. (2018). Biotransformations in Organic Chemistry (7th ed.). Springer. ISBN: 978-3319615227; Jacobsen, E. N., Pfaltz, A., & Yamamoto, H. (Eds.). (1999). Comprehensive Asymmetric Catalysis. Springer; International Union of Pure and Applied Chemistry. Compendium of Chemical Terminology (Gold Book) - Definitions related to kinetic resolution and stereoselective reactions.
Key Distinction: Kinetic Resolution (KR): Separates enantiomers based on different reaction rates; maximum theoretical yield = 50% of the desired enantiomer. Dynamic Kinetic Resolution (DKR): Combines kinetic resolution with in situ racemization of the slower-reacting enantiomer; theoretical yield can approach 100%. Chiral Resolution: A broader term encompassing all methods used to separate enantiomers, including kinetic resolution. Enantioselectivity: The preference for formation or consumption of one enantiomer over the other during a reaction.