not-yet-known not-yet-known not-yet-known unknown A tandem Diels–Alder reaction / aza-Claisen rearrangement / decarboxylation strategy of N-allenamides with 3-alkoxycarbonyl-2-pyrones has been developed for the efficient synthesis of diarylmethanes with moderate to good yields. The reac-tion exhibits good functional group tolerance and can be applied to late-stage modifications of known drug molecules. Mechanistic studies indicate that the ester group at the 3-position of 2-pyrones is essential, and the initial Diels–Alder reaction between the 2-pyrones with the proximal C=C bond of the N-allenamides is crucial for the success of the reaction.