Rhodium-mediated asymmetric transfer hydrogenation: a diastereo- and enantioselective synthesis of syn-α-amido β-hydroxy esters

The preparation of syn alpha-benzoylamido beta-hydroxy esters through asymmetric transfer hydrogenation (ATH) with a tethered Rh(III)-DPEN complex via dynamic kinetic resolution (DKR) has been developed for the first time starting from alpha-benzoylamido beta-keto esters. A variety of alpha-benzoylamido beta-keto esters were converted under mild conditions into the corresponding syn alpha-benzoylamino beta-hydroxy esters with high yields (up to 98%) and diastereomeric ratios (up to 499 : 1 dr) as well as excellent enantioselectivities (up to 499% ee).