Combination of the Suzuki–Miyaura Cross‐Coupling Reaction with Engineered Transaminases

The combination of enzymatic and chemical reaction steps is one important area of research in organic synthesis, preferentially as cascade reactions in one‐pot to improve total conversion and achieve high operational stability. Here, the combination of the Suzuki–Miyaura reaction is described to synthesize biaryl compounds followed by a transamination reaction. Careful optimization of the reaction conditions required for the chemo‐ and biocatalysis reaction enabled an efficient two‐step‐one‐pot reaction yielding the final chiral amines with excellent optical purity (>99 % ee) in up to 84 % total conversion. Key to the success was the protein engineering of the amine transaminases from Asperguillus fumigatus (4CHI‐TA) where single alanine mutations increased the conversion up to 2.3‐fold. Finally, the transfer to a continuous flow system after immobilization of the best 4CHI‐TA variant is demonstrated. The combination of amine transaminase (ATA) activity and the Suzuki–Miyaura cross‐coupling reaction in a two‐step‐one‐pot fashion is presented. The biaryl amines were obtained with high conversion and excellent enantiomeric excess (99 % ee) using isopropylamine as the amine donor after engineering of the transaminase from Asperguillus fumigatus.