In Situ Formed Bifunctional Primary Amine–Imine Catalyst for Asymmetric Aldol Reactions of α‐Keto Esters

In prime condition: The hydrolysis of a chiral diimine precursor can be carried out by a Brønsted acid to form an in situ primary amine–imine intermediate as a bifunctional primary aminocatalyst, which promoted direct asymmetric aldol reactions between α-keto esters and ketones in high yields (up to 88 %) and with excellent enantioselectivities (see scheme; R1, R2, R4=alkyl; R3=aryl).