Stereocomplementary Synthesis of a Key Intermediate for Tofacitinib via Enzymatic Dynamic Kinetic Resolution‐Reductive Amination

Abstract Tofacitinib is an oral protein tyrosine kinase inhibitor approved for the treatment of rheumatoid arthritis, active psoriatic arthritis and ulcerative colitis. Its efficient production remains a challenge due to the two consecutive stereogenic centers associated to the piperidine ring. In this study, an enzymatic dynamic kinetic resolution‐asymmetric reductive amination was developed to prepare enantiomerically complementary cis ‐1‐benzyl‐ N ,4‐ dimethylpiperidin‐3‐amine and its analogues. Two enantiocomplementary imine reductases (IREDs) were identified for the synthesis of (3 R ,4 R )‐ and (3 S ,4 S )‐1‐benzyl‐ N ,4‐dimethylpiperidin‐3‐amine in high isolated yields (83% and 91%) with excellent stereoselectivity (97% and >99% ee values) and diastereoselectivity (>99:1 dr ), providing a green methodology for the production of the key intermediate of tofacitinib. magnified image