1-Benzyl-4-methyl-piperidin-3-one hydrochloride was used for the preparation of key intermediates of tofacitinib. Protein IR89 was utilized to catalyze the generation of (3R, 4R)-1-benzyl-N, 4-dimethylpiperidin-3-amine dihydrochloride from 1-benzyl-4-methylpiperidin-3-one or its hydrochloride and methylamine or its hydrochloride.
