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Synthesis of Ezetimibe chiral auxiliary using engineered HHDH enzymes : A path to sustainable chemistry
The pharmaceutical industry is continuously exploring innovative approaches to synthesise complex molecules more efficiently and sustainably . Enzyme engineering has become a pivotal tool in this endeavour , enabling the development of biocatalysts like halohydrin dehalogenases ( HHDHs ) that facilitate the production of chiral intermediates essential for drug synthesis . These enzymes offer a green alternative to traditional chemical methods , for instance in the synthesis of APIs , such as Ezetimibe .
Introduction to enzyme engineering
Enzyme engineering is the process of designing and modifying enzymes to enhance their natural capabilities or impart entirely new functions . Enzymaster ’ s scientists can identify and tailor enzymes to perform specific reactions with high efficiency , selectivity and stability under industrial ( reaction ) conditions using our proprietary BioNavigator ® and Bioengine ® platforms for enzyme screening and engineering .
This customisation allows enzymes to catalyse reactions that are challenging or very inefficient using traditional chemical catalysts or wild-type / non-optimised enzymes , making enzyme engineering a cornerstone of modern biocatalysis .
Figure 2 – Enzymaster ’ s service offer
Ezetimibe synthesis & the role of HHDHs
Ezetimibe , a cholesterollowering medication , requires the synthesis of chiral intermediates such as the Evans auxiliary ( S ) - 4-phenyl-2-oxazolidinone . Conventional methods to produce this compound involve multiple steps and the use of environmentally harmful chemicals , such as propionyl chloride , ethyl hydrogen sulfide and methylbenzene . Using HHDHs instead not only reduces the environmental footprint of the synthesis process but also improves the overall efficiency and yield .
Power of HHDH enzymes
HHDHs exemplify the potential of enzyme engineering in the production of chiral intermediates . These enzymes naturally catalyse the reversible dehalogenation of ( vicinal ) halohydrins to epoxides .
Utilising the reverse reaction , a variety of chiral compounds is accessible via an enantio- and regioselective ring-opening reaction ( Figure 1 ) by alternative nucleophiles . Depending on the nucleophile used and the enzyme variant , different chiral precursors can be obtained , such as Evans auxiliary for Ezetimibe synthesis ( left )" to “ chiral precursors can be obtained , such as Evans auxiliary for Ezetimibe synthesis ( left in Fig . 1 ).
This selective ring-opening is crucial for the enantioselective synthesis of key API intermediates . By means of enzyme engineering , our scientists were able to improve the wild-type variant tenfold regarding chemoselectivity with a 90-fold increase in substrate loading , creating a robust industrial catalyst that is used for tonne-scale production of the Ezetimibe intermediate today .
Figure 1 - HHDH as a platform technology
HHDHs as a platform technology
The versatility of HHDHs combined with enzyme engineering underscores their potential as a platform technology for a wide range of chemoenzymatic reactions . Beyond Ezetimibe , these enzymes can be adapted to synthesise other pharmaceutical intermediates and fine chemicals , such as intermediates for the APIs Mirabegron or Levamisole .
In conclusion , the integration of HHDHs into the synthesis of Ezetimibe API intermediates represents a significant leap forward in green chemistry . Enzyme engineering , by enabling the redesign and optimisation of these and other biocatalysts , offers the pharmaceutical industry powerful means to achieve sustainable production . As research in this field continues , the potential for enzymes like HHDHs to revolutionise drug synthesis and beyond becomes increasingly evident .
Reach out to learn more about our free workshop series on biocatalysis ! ●
J j
Dr Jan-Dirk Küsters-Spöring
BUSINESS DEVELOPMENT MANAGER
j . spoering @ enzymaster . de www . enzymaster . de
SEP / OCT 2024 SPECCHEMONLINE . COM
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