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An auto-tandem catalytic double allylic rearrangement of N-alloc-N-allyl ynamides was developed. This reaction proceeds through two separate and distinct catalytic cycles with both decarboxylative Pd-π-allyl and Pd(0)-promoted aza-Claisen rearrangements occurring. A detailed mechanistic study supported by computations highlights these two separate mechanisms. Previously unreported reversible C-N ionization and a Pd(0)-catalyzed [3,3]-sigmatropic rearrangement were discovered. This study provides new reaction pathways for both π-allyl and sigmatropic rearrangements.

The inherent reactivity of lignin in conventional biomass processing commonly prevents isolation of native lignin and limits monomer yields from catalytic depolymerization strategies that target aryl-ether bonds. Here we show that flow-through solvolysis with methanol at 225 °C produces native-like lignin from poplar, enabling the study of intrinsic lignin properties and evaluation of steady-state lignin depolymerization processes.