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Stereodivergent Biocatalytic Formal Reduction of α-Angelica Lactone to (R)- and (S)-γ-Valerolactone in a One-Pot Cascade |
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| Authors: | Alessia Tonoli Karla Wagner Arianna Bacchin Tamara Reiter Prof?Dr Elisabetta Bergantino Dr Marina S Robescu Prof?Dr Mélanie Hall |
| Affiliation: | 1. Institute of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria;2. Institute of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
These authors contributed equally to this work.;3. Department of Biology, University of Padova, Via U. Bassi, 58/B, 35121 Padova, Italy |
| Abstract: | The formal asymmetric and stereodivergent enzymatic reduction of α-angelica lactone to both enantiomers of γ-valerolactone was achieved in a one-pot cascade by uniting the promiscuous stereoselective isomerization activity of Old Yellow Enzymes with their native reductase activity. In addition to running the cascade with one enzyme for each catalytic step, a bifunctional isomerase-reductase biocatalyst was designed by fusing two Old Yellow Enzymes, thereby generating an unprecedented case of an artificial enzyme catalyzing the reduction of nonactivated C=C bonds to access (R)-valerolactone in overall 41 % conversion and up to 91 % ee. The enzyme BfOYE4 could be used as single biocatalyst for both steps and delivered (S)-valerolactone in up to 84 % ee and 41 % overall conversion. The reducing equivalents were provided by a nicotinamide recycling system based on formate and formate dehydrogenase, added in a second step. This enzymatic system provides an asymmetric route to valuable chiral building blocks from an abundant bio-based chemical. |
| Keywords: | asymmetric reduction biocatalysis isomerization lactone Old Yellow Enzyme |