Direct enantioselective amination of α-ketoesters catalyzed by an axially chiral guanidine base

β-functional! Direct enantioselective amination of α-ketoesters with azodicarboxylates was demonstrated using an axially chiral guanidine base catalyst, which enabled efficient access to enantioenriched multifunctionalized ketoesters with an aliphatic substituent at the β-position. Subsequent nucleophilic addition to the β-hydrazinyl-α-ketoester at the reactive ketone yields the corresponding β-hydrazinyl-α-hydroxy esters in high syn diastereo- and enantioselectivities (see scheme).