One‐Pot Cascade Synthesis of (3 S )‐Hydroxyketones Catalyzed by Transketolase via Hydroxypyruvate Generated in Situ from d ‐Serine by d ‐Amino Acid Oxidase

We described an efficient in situ generation of hydroxypyruvate from d ‐serine catalyzed by a d ‐amino acid oxidase from Rhodotorula gracilis . This strategy revealed an interesting alternative to the conventional chemical synthesis of hydroxypyruvate starting from toxic bromopyruvate or to the enzymatic transamination from l ‐serine requiring an additional substrate as amino acceptor. Hydroxypyruvate thus produced was used as donor substrate of transketolases from Escherichia coli or from Geobacillus stearothermophilus catalyzing the stereoselective formation of a carbon−carbon bond. The enzymatic cascade reaction was performed in one‐pot in the presence of d ‐serine and appropriate aldehydes for the synthesis of valuable (3 S )‐hydroxyketones, which were obtained with high enantio‐ and diastereoselectivity and in good yield. The efficiency of the process was based on the irreversibility of both reactions allowing complete conversion of d ‐serine and aldehydes.