But‐2‐ene‐1,4‐diamine and But‐2‐ene‐1,4‐diol as Donors for Thermodynamically Favored Transaminase‐ and Alcohol Dehydrogenase‐Catalyzed Processes

Abstract Both cis ‐ and trans ‐but‐2‐ene‐1,4‐diamines have been prepared and efficiently applied as sacrificial cosubstrates in enzymatic transamination reactions. The best results were obtained with the cis ‐diamine. The thermodynamic equilibrium of the stereoselective transamination process is shifted to the amine formation due to tautomerization of 5 H ‐pyrrole into 1 H ‐pyrrole, achieving high conversions (78–99%) and enantiomeric excess (up to >99%) by using a small excess of the amine donor. Furthermore, when the reaction proceeded, a strong coloration was observed due to polymerization of 1 H ‐pyrrole. A structurally related compound, cis ‐but‐2‐ene‐1,4‐diol, has been utilized as cosubstrate in different alcohol dehydrogenase (ADH)‐mediated bioreductions. In this case, high conversions (91–99%) were observed due to a lactonization process. Both strategies are convenient from both synthetic and atom economy points of view in the production of valuable optically active products. magnified image