Combining Incompatible Processes for Deracemization of a Praziquantel Derivative under Flow Conditions.
- Resource Type
- Article
- Authors
- Valenti, Giulio; Tinnemans, Paul; Baglai, Iaroslav; Noorduin, Willem L.; Kaptein, Bernard; Leeman, Michel; ter Horst, Joop H.; Kellogg, Richard M.
- Source
- Angewandte Chemie. 3/1/2021, Vol. 133 Issue 10, p5339-5342. 4p.
- Subject
- *DERACEMIZATION
*PACKED towers (Chemical engineering)
*ENANTIOMERIC purity
*PRAZIQUANTEL
*CRYSTAL growth
- Language
- ISSN
- 0044-8249
An efficient deracemization method for conversion of the racemate to the desirable (R)‐enantiomer of Praziquantel has been developed by coupling incompatible racemization and crystallization processes. By a library approach, a derivative that crystallizes as a conglomerate has been identified. Racemization occurs via reversible hydrogenation over a palladium on carbon (Pd/C) packed column at 130 °C, whereas deracemization is achieved by alternating crystal growth/dissolution steps with temperature cycling between 5–15 °C. These incompatible processes are combined by means of a flow system resulting in complete deracemization of the solid phase to the desired (R)‐enantiomer (98 % ee). Such an unprecedented deracemization by a decoupled crystallization/racemization approach can readily be turned into a practical process and opens new opportunities for the development of essential enantiomerically pure building blocks that require harsh methods for racemization. [ABSTRACT FROM AUTHOR]