Laurence Hecquet

We described a strategy for the enzymatic synthesis of 1‐deoxy and 1,2‐deoxyketoses from the aliphatic α‐ketoacids, pyruvate and 2‐oxobutyrate, as donors and natural aldoses of variable chain length as acceptors, catalyzed by thermostable transketolase variants from Geobacillus stearothermophilus (TK gst ). Analytical studies have been carried out on a panel of TK gst variants with the appropriate substrates allowing to select the best combinations and to apply it to the preparative scale synthesis of 1‐deoxy and 1,2‐deoxyketoses obtained with good to excellent isolated yields (61%–86%). To optimize the strategy, and as a proof of principle, the α‐ketoacids pyruvate and 2‐oxobutyrate were generated in situ from the corresponding d ‐amino acids d ‐alanine and d ‐homoalanine respectively, using a thermostable d ‐amino acid oxidase d AAO4536 that was selected from a screening of 55 putative DAAOs provided by Prozomix Limited. Hence, a one‐pot one step procedure was performed at 50 °C by coupling d AAO4536 and the best TK gst variant H102L/L118I/H474S in the presence of d ‐alanine or d ‐homoalanine as α‐ketoacids precursors and d ‐erythrose as acceptor substrate. The corresponding 1‐deoxy and 1,2‐dideoxyketoses were isolated with good yields (64% and 72% respectively, out of two steps). magnified image