CuII‐Containing 1‐Aminocyclopropane Carboxylic Acid Oxidase Is an Efficient Stereospecific Diels–Alderase

In the context of developing ecofriendly chemistry, artificial enzymes are now considered as promising tools for synthesis. They are prepared in particular with the aim to catalyze reactions that are rarely, if ever, catalyzed by natural enzymes. We discovered that 1‐aminocyclopropane carboxylic acid oxidase reconstituted with Cu^II served as an efficient artificial Diels–Alderase. The kinetic parameters of the catalysis of the cycloaddition of cyclopentadiene and 2‐azachalcone were determined (K_M=230 μm , k_app=3 h^?1), which gave access to reaction conditions that provided quantitative yield and >99 % ee of the (1S,2R,3R,4R) product isomer. This unprecedented performance was rationalized by molecular modeling as only one docking pose of 2‐azachalcone was possible in the active site of the enzyme and this was the one that leads to the (1S,2R,3R,4R) product isomer.