Threonine aldolases—an emerging tool for organic synthesis

In a systematic study, 21 ring-substituted benzaldehydes were reacted with glycine under catalysis with a l-threonine aldolase (lTA) from Pseudomonas putida and a d-threonine aldolase (dTA) from Alcaligenes xylosoxidans to form the corresponding β-hydroxy-α-amino acids 1–18. dTA proved to be highly selective with eeʹs >99% (d) and deʹs up to 99% (syn). Two thiamphenicol precursors were synthesized utilizing dTA on a preparative scale. lTA-catalyzed reactions led to eeʹs >99% (l) but low to moderate deʹs (20–50%, syn).