Asymmetric Synthesis of Saxagliptin Intermediate, 2-(3-hydroxy-1-adamantyl)-(2S)-amino ethanoic acid, by Coupling Two Enzyme Reactions

Saxagliptin is a pharmaceutical chemical used for treatment of type 2 diabetes. We prepared 2-(3-hydroxy-1-adamantyl)-(2S)-amino ethanoic acid which is an intermediate of saxagliptin, by coupling two enzyme reactions. Both Branched-chain amino transferase (BcAT) from Enterobactor sp. and aspartate amino transferase(AAT) from E.coli were transformed into the E.coli BL21(DE3). 2-(3-hydroxy-1-adamantyl)-2-oxoethanoic acid was applied as the substrate for the transaminase reaction. The activity of the enzyme was analyzed with HPLC after2,3,4,6-tetra-O-acetyl-D-glucopyranosyl isothiocyanate(GITC) derivertization. This enzyme reaction performed high (s)-form enantioselectivity which was 99.9% ee. Though BcAT alone showed activity toward the substrate, coupling AAT shifted the equilibrium constant and made 1.7fold higher product yield.