Efficient Epoxide Hydrolase Catalyzed Resolutions of (+)‐ and (−)‐cis/trans‐Limonene Oxides

Abstract

The synthesis of enantiomerically pure cis‐ and trans‐limonene oxides and their corresponding diols from easily accessible raw materials has been of much interest for a long time. A straightforward one‐step biocatalytic resolution of the (+)‐cis/trans limonene oxide and the (−)‐cis/trans‐limonene oxide has been investigated. Epoxide hydrolases showing complementary stereoselectivity were recombinantly expressed in Escherichia coli, which allowed easy purification. The conditions for the selective epoxide hydrolase catalyzed ring‐opening reactions have been optimized and enabled the preparation of all limonene oxide enantiomers. The described utilization of recombinant epoxide hydrolases for the synthesis of all limonene oxide enantiomers was superior to chemical routes and represents a highly resource‐efficient one‐step preparation.

Horizons of Systems Biocatalysis and Renaissance of Metabolite Synthesis

“…Enzymatic hydrolysis of easily accessible racemic epoxides with epoxide hydrolases has enabled the synthesis of chiral epoxides and vicinal diols . All four limonene oxide enantiomers, the (1 S ,2 S ,4 R )‐limonene‐1,2‐diol and the (1 R ,2 R ,4 S )‐limonene‐1,2‐diol could be prepared (Figure B) by the resolution of mixtures of (+)‐ cis / trans ‐limonene oxide as well as (−)‐ cis / trans ‐limonene oxide …”

“…The common inhibition of enzymatic reactions by substrates, products or byproducts can be overcome by a number of different approaches, such as using solid adsorbents for substrate and product inhibition, protecting reactive aldehyde groups as dimethylacetals or utilizing an enzymatic reaction for removing an inhibiting byproduct . Experimental investigations of enzyme activity and stability as a function of pH, temperature, cosolvents or neat substrates can lead to optimum reaction conditions with high space‐time yields . Instead of selecting the reaction and process conditions which are most suitable for a given enzyme, the development or improvements of suitable enzymes matching the process requirements has become an attractive option .…”

Biocatalytic Process Design and Reaction Engineering

“…In the development of a one-step route to KDG, the simultaneous qualitative and quantitative analysis of D-gluconate and 2-keto-3-deoxy-D-gluconate by LC-MS for reaction monitoring and a recombinant gluconate dehydratase enabled the efficient and selective biocatalytic water elimination reaction 34 . The bottleneck in the synthesis of all limonene oxide enantiomers and their corresponding diols has been overcome by the discovery of epoxide hydrolases with complementary stereoselectivity and their recombinant expression in E. coli in highly resource-efficient one-step biocatalytic resolutions of (+)-cis/trans limonene oxide and (−)-cis/trans-limonene oxide [55][56] . Although biocatalysts have been discovered for an increasing number of reaction types, it is rare that large numbers of different substrates can be converted with high efficiency by the same enzyme.…”

“…In the case of the biocatalytic resolution of (+)-cis/trans limonene oxide and (-)-cis/trans-limonene oxide, the choice of the most suitable reaction parameters, like substrate loading, pH, tem-F i g . 5 -Bioinspired biocatalytic process design strategies perature and cosolvents, was based on experimental investigations of limonene oxide stability, epoxide hydrolase stability and activity as a function of pH and temperature [55][56] . The optimization of the reaction conditions for these epoxide hydrolase-catalysed resolutions has led to improved space-time yields and specific productivities with up to 2 M substrate concentrations and lower enzyme consumption numbers, without the need for cosolvents 56 .…”

Bonding (especially C−C bonding) with Woody Fessner

“…Cascade coupling of ene‐reductases and ω‐transaminases for the stereoselective synthesis of diastereoisomerically enriched amines are presented by the group of Sergio Riva . Sergio Riva and Roland Wohlgemuth use epoxide hydrolases for the resolution of limonene oxides, another important contribution of biocatalysts to provide asymmetric products . In a related field, the groups of Bornscheuer and Masterson report on the interaction of co‐solvent with substrates when using pig liver esterase in the hydrolysis of malonate esters …”