1: sodium hydroxide / N,N-dimethyl-formamide / 6 h / Inert atmosphere 2: triethylamine / isopropanol acetate / 1.25 h / 0 - 10 °C / Inert atmosphere 3: sitagliptin transaminase CDX-017; triethanolamine; pyridoxal 5'-phosphate; N-isopropylamine hydrochloride / water; dimethyl sulfoxide / 11 h / 40 °C / pH 9.5 / Inert atmosphere 4: potassium carbonate / isopropanol acetate; water / 1.25 h / 0 °C / Inert atmosphere View Scheme

1: sodium hydroxide / N,N-dimethyl-formamide / 6 h / Inert atmosphere 2: triethylamine / isopropanol acetate / 1.25 h / 0 - 10 °C / Inert atmosphere 3: sitagliptin transaminase CDX-017; triethanolamine; pyridoxal 5'-phosphate; N-isopropylamine hydrochloride / water; dimethyl sulfoxide / 40 °C / pH 9.5 / Inert atmosphere View Scheme