Decarboxylative Mannich Reaction of N,O-Aminals and β-Keto Acids without an Additional Catalyst

We develop the first decarboxylative Mannich reaction of N,O-aminals and β-keto acids without an additional catalyst, which undergoes smooth decarboxylation and subsequent Mannich addition via an iminium-ion-pair intermediate under mild conditions. The process exhibits broad substrate compatibility, as demonstrated by 40 examples (43%-97% yield). Furthermore, the synthetic utility was shown by preparing aziridine, oxazole, and oxazoline derivatives. This strategy obviates the need for exogenous catalysts or strictly anhydrous conditions, thereby overcoming key drawbacks associated with traditional imine-based decarboxylative Mannich reactions.