Biocatalytic Asymmetric Cyclopropanations via Enzyme‐Bound Iminium Ion Intermediates. Issue 45 (5th October 2021)

• Record Type: Journal Article
• Authors: Kunzendorf, Andreas; Xu, Guangcai; Saifuddin, Mohammad; Saravanan, Thangavelu; Poelarends, Gerrit J.
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 45(2021)
• Page Start: 24059
• Page End: 24063
• Publication Date: 2021-10-05
• Subjects: biocatalysis -- catalytic promiscuity -- cyclopropanation -- enzyme engineering; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202110719
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Cyclopropane rings are an important structural motif frequently found in many natural products and pharmaceuticals. Commonly, biocatalytic methodologies for the asymmetric synthesis of cyclopropanes rely on repurposed or artificial heme enzymes. Here, we engineered an unusual cofactor‐independent cyclopropanation enzyme based on a promiscuous tautomerase for the enantioselective synthesis of various cyclopropanes via the nucleophilic addition of diethyl 2‐chloromalonate to α, β‐unsaturated aldehydes. The engineered enzyme promotes formation of the two new carbon‐carbon bonds with excellent stereocontrol over both stereocenters, affording the desired cyclopropanes with high diastereo‐ and enantiopurity (d.r. up to 25:1; e.r. up to 99:1). Our results highlight the usefulness of promiscuous enzymes for expanding the biocatalytic repertoire for non‐natural reactions. Abstract : Engineering of a promiscuous 4‐oxalocrotonate tautomerase (4‐OT) resulted in an unusual cofactor‐independent cyclopropanation enzyme that promotes the stereoselective addition of diethyl 2‐chloromalonate to substituted cinnamaldehydes to afford various cyclopropanes with high diastereo‐ and enantiopurity.