Cascade Coupling of Ene-Reductases and omega-Transaminases for the Stereoselective Synthesis of Diastereomerically Enriched Amines

One-pot sequential and cascade processes performed by employing ene-reductases (ERs) together with -transaminases (-TAs) for the obtainment of diastereomerically enriched (R)- and (S)-amine derivatives containing an additional stereocenter were investigated. By using either - or -substituted unsaturated ketones as substrates and by coupling purified ERs belonging to the Old Yellow Enzyme (OYE) family with a panel of commercially available -TAs, the desired products were obtained in up to >99% conversion and >99%de. The sequential reactions were performed in a one-pot fashion with no need to adapt the reaction conditions to the reductive amination step or to purify the reaction intermediate. Moreover, high chemoselectivity of the tested -TAs for the saturated ketones was shown in the cascade reactions.